Run capacitors fail so often, especially in hotter climates for one simple reason, the capacitors you get today are poorly made. They are insulated and cooled internally as cheaply as possible, even the ones installed in units from the factory.
@@CactusBobsPlace In NY I just replaced mine after 25 years when the fan needed replaced for the first time, the other unit still has the original cap.
Amrad capacitors are guaranteed for 5 years... I match my labor to their caps for good reason... the "el-cheapo" caps MIGHT last 2 summers... two service calls (let alone el cheapo) pay for ONE service call with an installed AMRAD... I put my name on an AMRAD for 10 years... I don't warranty them for that long... but I know AMRAD to last for ABOUT 15 years... YES, THEY ARE THAT GOOD!
The main cause is not cheap production, its the environmentalists. The chemicals to produce more reliable capacitors have been forbidden about 20 years ago, thats when the quality went downhill.
@@joskevermeulen9275 No, it's cheap products. The Chinese caps are the worst. They are tiny compared to, say, US-made GE caps (back when GE owned the plant and made them here). Capacitors generate heat during operation, and that heat has to be dissipated. also, a smaller capacitor is made by using thinner aluminum deposition (which means higher internal resistance) and thinner polymer separator (which has higher loss). Combine all these cost saving "features" and you inevitably have a capacitor with a shorter life.
Brilliant demonstration! For anybody who is interested, there is an explanatory article showing the math more completely, written by Bryan Orr in AC news, titled "Testing the Run Capacitor While the System is Running", found with Google. Basically the 2652 comes from Xc=(1/(2*pi*f*C)), with 2652 in microfarads = 10^6/(2*pi*f). f is assumed 60 Hz. So, Xc = 2652/C, in microfarads. Plug that into Ohm's law E=I*Xc and rearrange to isolate C. So, C=2652*I/E. Remember that the start cap is only in the circuit for a short time at each start, so this measures only the run capacitor quality. For the brief episode when both are in the circuit, the capacitance for the two parallel lines is additive.
You must be young, that was the transitional period when PCB capaciters were eliminated from availability. The new non PCB caps were large until they got the design correct.
The older larger caps were always paper caps, and as such had a (sometimes poorly defined) limited life span. Modern caps are often polypropylene and "should" last longer. Of course, they don't always last longer in practice as it's fully possible to underrate them as well. They might even be more prone to heat damage than a properly manufactured (very expensive) paper capacitor.
I always look at rated voltage on a cap. If a higher rated voltage capacitor is in stock, we use them as the capacitance is only affected by back EMF, so a higher rated (sometimes 440V) voltage capacitor can "help out" in areas where voltage is inconsistent. A 220V rated capacitor can fail with spikes/lightning in area as stated. Good work Bryan!
yep exactly! Some ppl confuse voltage rating and capacitance. The untold capacitor spec is internal *impedence*... larger caps have a lower impedance and higher voltage rating
Same here!! I once had a bad mechanical thermostat that did that sometimes and it was making that awful sound, now I know that it was running backwards. It did actually blow the start capacitor. The only time I've ever blown a start capacitor. Hard to think that it's a coincidence.
Great lesson. I don't care how long if be doing this business there's always something to learn . I've been here for 50 years everyday there's a new idea or approach to things I've been doing for years. Thank you
Thanks, very instructive video. My choice would be to always use a 440 Volt capacitor as long as there is physical space to accommodate it. It is worth any extra expense. The other thing is to check carefully that all connections are clean and tight. Check terminals on the capacitor, but also check the contactor and any terminal blocks. Failing connections in various locations could increase motor back EMF, causing higher voltage across the capacitor.
Old Caps were much bigger in the earlier years (50's-70's) so they held more oil to keep them cooler. Ambient heat is the number one cause of failed capacitors here. Some condensers (Ruud for example) have the capacitor in the fans airflow- you'll notice these last longer. Pay attention to periodic potential start relays sticking.
The reason those old caps were bigger is because they used paper as the separators between the foil plates. When they went to polymer separators, they were able to make them smaller. Then they went to metallized polypropylene, making them smaller yet. But, there was a limit to how small they could be made and still have long life and good surge capacity. When you start making them as small as the import caps, there's no way they can be expected to last.
I have a 1990's Rudd 2 1/2 ton with capacitors that mount into cutouts in the contactor connection box, and the cases, except for the top connections, are in the cooling airflow. Luckily, I found properly sized US made caps to replace them with, along with a new Eaton contactor.
Best video on the subject. EVER! BTW, I always use caps with a dielectric strength of 440v vs. 377v. I suspect they're more robust in handling those pesky transients.
The main reason that run caps fail is primarily the printing on the label. 30 -40 years ago it was quite uncommon for them to fail. I've found caps out of the box that were out of the 15% rule of thumb. The most problem caps have printing on the label reading "PRC" and thats a big problem
Regarding surge suppression we need to keep in mind that MOVs degrade over time due to the number of surges and their amplitude. You can have an MOV that looks perfectly fine but is no longer providing surge suppression.
More than once I've also seen them fail in a dangerous way, where the MOV was conducting enough to make it heat up and catch fire while not drawing enough current to blow the fuse. For this reason I do not use any MOV based surge protectors that have a plastic housing, I've seen power strips that completely melted down and we had a UPS at work catch fire about 15 years ago.
@@James1095 It's true, as the voltage rises across an MOV, the resistance drops proportionately. It can easily reach a point where the amount of current through the MOV will get hot, catch fire and or blow apart.
DoctorT327 you nailed it. Those big run capacitors were made with pcbs and made in the USA, both of which no longer happen. They would fail, but it was rare.
You failed to consider what happens if a compressor's connections are loose. Consider what happens when a motor (inductor) is running with loose connections. A sudden disconnect on an inductive circuit causes voltage spikes of unlimited voltage- like your car's spark plug coil. So, age, but primarily voltage spikes resulting from bad compressor connections (or fan) cause most capacitor failures. The spikes violate the capacitor's dielectric material resulting in a short, intense heat, and then an explosion. Check for good electrical connections at the compressor and at all connecting points in the system- the number one preventive measure! I've seen it many times.
My A/C unit was actually eating run caps so I decided to check all of the wire connections. I found one of the ears was broken on a female spade connector that was connected to the low voltage coil on the contactor. Once I fixed that connector, I never had to replace another run capacitor on the condensing unit until the compressor died 10 years later. The really amazing thing is that the condenser fan motor was made by GE and it ran for almost 28 years without failure. I would oil the sleeve motor bearings every Spring.
I just replaced a cap and found a loose spade terminal. A loose terminal will cause it to overheat and burn the terminal and spade connector, wire, leaving a crispy mess and possibly a damaged compressor. Always make sure those spade terminals aren't loose.
I'm an HVAC Contractor in the Metro Phoenix area. I've got units 2-3 years old with dead caps under warranty and we literally just experienced the hottest June in history and I emptied out multiple 5 gallon buckets of dead caps over the last 5-6 weeks. They are poorly made and 117 degrees plus, sustained over time fucks em' up. EXTREME HEAT kills them.
Lived in Phoenix for decades. People don't understand just how fast caps die in that area. HVAC, Pool pump motors, car batteries, car belts, tires, etc. The heat just destroys everything. They won't even warranty tires for much over half the original warranty.
I would think that it may be likely that 117 temps ambient could end up 150 degrees under the cover if direct sunlight is bearing down on it. Possibly something to cast a shadow on the unit might help a little bit. Also 140 degree air inside the cabinet is going to affect the cap temp too.
Capacitors fail for several reasons, mostly heat and the surge cycling over time, basically because capacitors are not built to last as they once were, using inferior materials to keep production costs down. If a capacitor has been replaced in the past, if could very well be the original was replaced with a less reputable product. The voltage rating of a capacitor: is the amount of voltage a capacitor can handle on "peek demand", not what the unit runs at. The unit may run on 220-240v but the start up demand is much higher, sometimes peeking at 290v. The mfd is the charge/discharge rate of capacitor, the lower the mfd rating is, the higher charge/discharge rate. Always try to match the mfd and voltage as close as you can, if not, always go with the higher voltage rating and or a smaller mfd rating but don't make drastic mfd changes. When you are replacing a capacitor, take into consideration the age of the unit, how old is the cap and is there rust or powder present on the cap. Capacitors dry out with age, and you will get swelling, a liquid dripping or a fine powder forming on the capacitor, or an outright exploded capacitor. The powder is the dielectric drying out due to over use or just plain crappy dielectric, the liquid present is also the dielectric leaking due to expansion, the swelling is due to the dielectrics reaction with inferior materials used inside the capacitor in production, an exploded cap tells you there is too much voltage demand on the capacitor and you may want to consider a higher voltage rating when replacing it. If you replace a cap 40mfd @ 250v with the same, it will perform "as designed", you can also safely replace that same capacitor with one rated for higher voltage (40mfd @ 350 or 450v)m and it will perform as designed or better due to the higher voltage handling capability, manufacturers use absolute ratings for cost and effective production. What I mean is, higher voltage rated capacitors are going to cost more and will perform just as well and also have a longer life, but that cost may be prohibitive to the production costs, therefore manufacturers will go with the less expensive unit to save on cost. If you have a high rate of failure on this system, you may want to consider upping the voltage capacity of the capacitor, but match the mfd rating. The reason for this is due to the draw surge in electron demand on startup, the unit may now be demanding a higher capacity due to age and wear. If a unit is not maintained properly, it's demand will increase and cause a higher demand in startup voltage. As things get older the voltage demand increases, wearing of parts, lack of maintenance and whatnot. Also if the compressor HAS been replaced but the capacitor has not, the compressor and capacitor are not matched. The compressor may be a direct replacement but the physics demands may have changed. Therefore the voltage demand on startup may not be the same rating, and the capacitor voltage rating needs to match the demand. The way to figure this out is if the compressor seems to be sluggish when starting, then you know you need to lower the mfd for a faster start rate. If the compressor starts and stops a couple times or seems hesitant, it could be the mfd rate is too low and needs to be increased to allow the compressor to get a good start rate. The lower the number MFD the faster the start rate. As an example: 50 MFD will start the motor faster than a 70MFD because it takes less time to recharge the capacitor. I hope this helps. (43 years experience)
"50 MFD will start the motor faster than a 70MFD because it takes less time to recharge the capacitor" If that were true, adding a start kit, 389-524 mfd, it would further slow the compressor start, but in real life, it actually speeds up the compressor start, according to the manufacture. Even so, there is no reasonable field way to time the compressor sta, maybe in a lab....
My compressor Ran backwards all day. My wife ignored my advice and didn’t turn it off. It was hot as heck when I got home. I let it cool for an hour and turned it back on. It was fine and worked. The unit was already 10 years old so I called my friend and got an estimate for a new one figuring the compressor was going to die. That was in 2014. It’s still fine and runs perfectly. I’m in south Florida so it runs 12 months out of the year.
Much obliged for a comprehensive explanation of running caps. I have chastised my various HVAC Techs for replacing them (mostly as a revenue increaser) when, in fact that was unlikely the problem. The 'American made' recommendation is most appropriate!
I've seen in desert areas where the contractor put in a relatively cheapcompressor where the capacitors that fail rated to 40C in an area where it can be constantly above 45C (114F). These need to be replaced but a Cap rated to 70C (158F) to minimize it's failing.
Keep in mind that the capacitor is also a chemical based component and over time they can actually dry out which causes the capacitor value to fall over time to the point that eventually the motor startup will fail.
I think that is what is happening to my 50 HP 3 phase converter (from single) I bought the unit with 33 50 up capacitors to start 50 HP. not enough now it won't start. trying to learn to fix it myself.
@@bradjunes1610 Do you have a meter to check the caps with? If you suspect the caps but don't have a meter you can always keep your fingers crossed and just swap them out.
23:23 into the video One of my experience out in the field was a surge right after a thunderstorm I've had a few replacement because of that. Coming from my perspective it was because high voltage like you stated!. I recommend to install a 'Surge Protector'. I explained what it could do and how it works they insisted so went ahead and installed it for them.
All I can say is wow. It was very intuitive. I've been in the field for over 25 years and learned a lot on this video, but with that said the old capacitors that had PCB in them and a resistor on the terminals lasted for decades or never failed before the unit rotted out. These days it's two years on a new unit 50% of the time. So
The purpose of resistor to bleed off residual voltage in the capacitor after been disconnected from the circuit after motor start up. PCBs, or polychlorinated biphenyls, are highly toxic industrial compounds. They pose serious health risks…
Many reasons.. surging grid volts is a biG one, no lead in the steel, or solder, the aluminum is low grade... here in FL, it's most often after lightning storms.. surge protector helps 50% of the time..
@@globedimmer8286 That's what I'm saying. It helps bleeding off the cap reducing it overheating and popping and as far as the PCB's.., I'd rather have one of them in a landfill compared to the 10 that haved popped open off a single system in a landfill.
As voltage goes up amperage goes down. The same is true in reverse. It must balance. If it does not balance heat is formed. If you have bad connections or BURNT CONTACTS which is the number one reason for capacitor failures, you will have voltage drop and heat formed. Heat is the root cause of capacitor failures. That is why very old large heavy oil filled Capacitors did not fail. They could disperse heat. Amperage draw increases heat which is a byproduct of electrical current. I spent 30 years of repairing and fixing electromechanical systems and equipment. From window units to 500 ton chillers in industrial sites. It all comes down to basics . I have held 50 year old capacitors in my hands that are just as good 50 years later as the day they were made and I have taken out bad ones that are less than a year old. Build quality is the greatest factor.
As a service technician, I've noticed some summers are capacitor hungry... some summers are fuse hungry... something tells me, the failure of capacitors OR fuses, is due to supplied power...
My next door neighbor has been in refrigeration for over 40 years. There were still US manufactured capacitors that contained PCBs when he started. They rarely failed... He still sees some old equipment during changeouts where the capacitor is still good. The pressure from Wall Street on HVAC manufacturers to maximize profits has driven them to "sell their souls" and purchase crappy off-shore components. My neighbor ONLY uses US made capacitors for replacement because he hates call-backs. Sadly, it's getting more difficult to source quality US made components... If you care about your customer, try to source US made 440V capacitors - ensure that all connections are clean, no burnt wires - and secure the capacitor properly (no duct tape)!
Capacitors, as they age, can develop series resistance (ESR), causing them to heat during use. Also, one should note that if the capacitor is not properly correcting for the inductive load (i.e. high amps, motor failing, wrong capacitor value), the voltage will be higher than the normal line voltage (back emf), and cause the capacitor to fail more quickly.
Nathan, so...could one then use a multi-value capacitor and a power factor meter or some other tester to dial in a "better" capacitor value for older systems or to compensate for wear/deviation from design?
Run caps used to use pcb oil known carcinogenic in their oil, outlawed now, now they use castor oil, and don't last as long In Florida units runtime is a lot more, its hotter longer, than other regions of country The power surges, lightning strikes, and brownouts cause high rate of failure Poor quality made in china caps fail prematurely, Most manufatures now use these sadly to save money, our company now only sells Made in. America 440volt rated capacitors and has had way less call backs on warranty failure of caps we install.
All the computers switched over to Japanese capacitors, much better quality. If you can get them, try looking for a Nichicon brand capacitor, I've had computers last 10 years in near continuous service without a capacitor failure in the power supplies that use that brand capacitor.
Excellent Video. Capacitors are one of the few components used in the HVAC industry that have actually gotten cheaper in the last 40 years. Some of this is due to materials used but a large part is because I could not find a manufacturer that still does testing on production lots (I had a reason at the time). It's simply cheaper to give you a new capacitor than run production lot tests. The number of capacitors that I've found outside tolerance straight out of the box in the last 10 - 15 years is a lot more than you might think.
I haven't seen one of those old Fedders since the early 80's. We had a Fedders unit on our house in 1972 and the compressor probably died because my parents never had the unit serviced.
I think you should also think about a chattering main contactor. It's impossible to change current instantaneously across an inductor... like a motor. Some insanely high voltages can be produced if your motor contactor is having intermittent contact and there is no resistor to drain the potential infinite voltages. These (discharging winding) spikes could easily damage a run capacitor if there is no other place for them to go. When you see a burned and pitted contactor, most likely the run cap has had a bad day in that situation. If there is no suppression between motor legs on the load side of the contactor this could be another factor. The same effect makes tennis racket bug zappers produce 2750 volts from two AA batteries.
an added note to those that fail to mount the run caps properly. These caps need that metal mounting strap as a heat since to dissipate the heat from the can to the surroundings. Failure of most electrical components is heat and moisture. I was wondering what effect using a higher or lower uf cap would have on a fan and compressor. These hard starts seem to work on out of warranty units to get em a few more years of life. How is this accomplished?
Very good theory to applied. Most caps fail because the dielectric material breaks down, accelerated by surge / strikes. Temperature is a factor, however, I haven't seen any research for long term with monitor of spikes/surge. The use of a properly sized MG set will take care of any line problems.
Run caps fail by building up internal pressure caused by heat from having high *current* combined with high *resistance* ie. impedence. Parasitic heat generated by caps: P = R x I2 The current being squared make caps particularly sensitive to it when internal impedence rise during aging. Good caps are known as "LOW ESR": Equivalent Serial Resistance which grants them long service life. Nothing magic: low-quality either builds repeat business or kills business like too many American iconic names 😂 OUT OF PHASE [23:00] : "Cap sends back"... nothing! The cap supplied voltage and drawn current is what is out of phase.
I live in South Carolina. I service thousands of roof top units. On an average day the ambient temperature on a tar and gravel roof will be about 145 degrees Fahrenheit. On a hot day where the air temperature is 95 degrees+ I’ve seen the roof temperature up to 160 degrees. I will always use capacitors rated at 440v. And if I have unit that is in a bad location where it has poor air flow or is next to and hood fan from a kitchen I will add a hard start. That may seem like overkill but it works every time.
In Portland Oregon, I replaced a lot of capacitors each summer. They typically run between 238 and 245 volts to most residential units with bad capacitors. When measuring across the two capacitor terminals while the compressor is running, I normally get between 400 and 426 volts, depending on the capacitor size, with the larger modern high efficiency units with huge capacitors running even higher than typical. A 4 ton system with a 65 Mfd capacitor is around 425 volts across the two terminals. Sometimes I see a 370 volt capacitor in the systems. You must use the 440 volt capacitors in Oregon, where the running voltage is normally very high. 370 volts will not survive very long. When I worked at a University, the main building had 67 water source heat pumps running at 208 volts, and I rarely ever had a capacitor fail in that building. But other buildings with 480 volts, or the residential units for student housing had capacitor losses.
This is amazing. I had not clue that so much is taking place in these things. The good part is, I'm a carpenter....being clueless is fine. tHanks for this great video! Love it
Run Capacitor Tunes the Sign Wave... Right. Kinda like a tune up on an engine. Makes the motor run smoother with less running amps at rated speed weather cking amps on comm or run. Full circuit is made from comm to runn ie:230vac line 1 and line 2 supply voltage. Very interesting in depth post.
For a capacitor, by definition I = C x dv/dt so if you are getting large changes of voltage in a short period of time, then current will increase. The easiest way to get a high dv/dt is to connect and disconnect an inductive load, e.g. a motor. These high voltage spikes are very short, so you will never see them on your meter, but you would see it on a peak detector or an oscilloscope. It's this peak voltage that occurs for only a very short period of time that kills a capacitor, not the average voltage. Of course heating and line voltage spikes will also cause premature failures...
I have studied electronics in depth in high school, trade school, and in college. Your explanations of the factors causing capacitors to fail was never mentioned. We analyzed inductive & capacitive reactance. Counter or back emf (voltage) was not discussed either. This analysis applied to actual compressor winding circuits helped to clarify many issues for me. Thank you.
Very informative. In my experience totaline seems to have the highest fail rate among manufactures. Ever since carrier started using them I noticed a big increase in failures
On the Texas Gulf Coast lightning "caused" power surges are common. I lost thousands of dollars in appliances and electronics; but I solved the problem 8 years ago. I installed an Eaton CHSPT2ULTRA surge protector on the load center. It has a surge current rating of 108 kA. Since then I have not lost anything. Best $200 I ever spent. It wont protect from a direct lightning strike like I had when 6ft of the chimney trim was blown off (nothing will do that); but it should protect for almost anything from the electrical lines.
I started adding some kind of start assist. It seems to have helped. I have had customers when looking at the history. I see run caps replaced every couple of years. I added a start assist and it's been 5 years so far. They are out in the country where surges are common.
I ended up installing a hard start kit (with the potential relay) in my A/C condensing unit and I installed a whole house surge protector in the power panel. I am thinking about adding another surge suppressor with brownout protection in my A/C disconnect to further protect my condensing unit. Over the years, I have lost a furnace blower motor to a power surge and lightning strikes have destroyed at least one of my TV's.
The basic problem is that the legacy American infrastructure does not provide 3-phase power to homes, because 100 years ago nobody expected us to be consuming $100s/month to power multi-horsepower rotating machinery (A/C compressors) all day long. This is a huge long-term waste and inefficiency. The capacitors are just a poor compromise to synthesize a second phase; it would be far better to just receive the three phases that the utility has nearby. But that would require an investment. ECM essentially converts single-phase to multi-phase, but the conversion is always significantly inefficient, and the converters are expensive, short-lived, and not ruggedly reliable, with costly maintenance.
Not sure if this applies to HVAC capacitors, but one of things we do in electronics is to measure the ESR of electrolytic capacitors to get an indication of it's health. If we see a capacitor with a higher than normal ESR, then we know that it's on it's way out. A capacitor with high ESR will run hotter, which in turn shortens its life. Also if we see a capacitor reading higher than it's rated capacitance, then that could be an indication that it is becoming electrically leaky and it's probably time to start thinking about replacing it. In electronics we generally consider Japanese and American capacitors to be the best for quality and life expectancy. Not sure if you can Japanese Rubycon HVAC capacitors?
Excellent video! Those of you with thumbs down, just don't understand the principles of electricity. My question is how much coffee did you drink before you did this video?
In my 40+ year old a/c I have the original dual run capacitor. One that is oval, 11" tall and has a ground spade, too. The unit also came stock with what is called a starter capacitor in the circuit. Though even with the starter capacitor exploded(I don't know when !, I just found a few days ago when I was doing a pre-run inspection)the unit still ran well last year in this condition ! I am replacing the starter capacitor before I attempt to run it...as a matter of fact USPS informed delivery says that it is out for delivery and I should have it today !!!
spend a little on maintenance parts to save a lot on not replacing with a new short-lived unit. Check your Starter Circuit that fried the cap... the day your compressor fails to start because of bad starter maybe one of its last days due to locked rotor high currents toasting old winding insulation. Little homework is worth your time... AC disconnect be your friend 👍🏻
4:08 Its actually a fixed amount of _charge_ (hence the microfarad being used, e.g. 5 uF) that can be stored. The current is only limited by the ESR of the capacitor and the circuit its hooked to.
Techs that don’t know capacitors, how they work or why they fail, are probably the same ones that charge by beer can cold and tell homeowners they need a new compressor and not just a cap. Very good video but every field tech should definitely already know all this.
The capacitor is kind of like two very large old-fashioned wire TV antennae that are folded and inter meshed with one-another, but never touching anywhere inside the container. Thus, they should have no possible way of conducting direct current inside them unless they develop a short circuit of some sort, called "leakage", which is bad news. They can also burn out and no longer conduct anything, which is a far safer way to fail. What they do is charge up the two interleaved antenna wires with a charge, on side being positive and the other negative, allowing them to soak up a rather large, for the size of the device, electrical voltage across the tiny internal gaps. How much current and voltage they handle defines their capacitance. To get a flow of power across the gap, you need AC current, since moving one side of the wires will move the other side like many tiny magnets on rollers next to one-another along each internal wire. The capacitance and voltage requirements on a capacitor tells you haw much charge can be stored inside (it can be large enough to kill you in some designs!) and how fast the frequency has to be that is being conducted to get certain amounts of power to go through the capacitor. Low capacitance devices need higher frequency AC to get enough flow, while large capacitance devices have a lot of "surface area" inside and can work at lower frequencies -- in electronic devices this controls what frequencies are allowed through various circuits and is what allows most of these things (smart phones, for example) to work. Storing charge to give a higher kick to a circuit, as being discussed in this video is the other major use.
My original run capacitor just lasted 21 years. I estimate I run the A/C for 500 hours each year, though, so that is only 10,500 hours -- far less than the 60,000-hour alleged design life. It was mounted with the connections pointing downward, so I assume this is what you mean by "upside down". Maybe it would last longer if I flip it around, but it seems like water could possibly collect on top. Nice job on the video!
When you consider the capacitor also acts as a HeatSink, Dirty Condenser, High Ambient Temperatures and Short Cycling are #1 causes. Always find out what MFD/Voltage Capacitor the motor requires. Just because the Condenser “looks” clean doesn’t mean it shouldn’t be cleaned.
after a few thousands cycles of the contactor the silver contacts become worn and arc, and the arcing induces voltage spikes that exceed the capacitors rated voltage and it pops, replace the contactor and capacitor at the same time
Love your podcasts and videos! Lot's of material and information in short period. I listen and watch over and over again to absorb the information. Was thrilled to discover your android app and have been using it the last couple days just for the capacitor in circuit tests. Makes very quick work of the formulas and nice you've included percentages in the results. Replaced 2 bad caps in 2 days and was actually surprised to find both new caps just slightly outside the 6% margin.
I'm finding that the 220 Volt Systems can range from 203-247 volts input; so if you have high or low 220 input would that not change the run cap MF load? If that were true the load would be different from the rated run cap and could that cause the issue of early run cap failure?
Really well done video! I’m an EE, but no experience with motors and capacitors. This all makes perfect sense, and thanks for the tip on AmRad! I followed the link to their site and learned about their Turbo 200 universal run caps. With a total of 6 HVAC units between two houses, I love the idea of being able to cover all of them with just one cap! (Only thing is, I assume the diameter will be larger than some of the standard caps, so I may have to fiddle with the mounting.) Besides the convenience, I love that they’re US-made.
Turbo200 3x-4x more costly than standard run cap & cost has to be passed on to customer= too expensive! Great versatility in a pinch, then can go back & install correct rated cap
Lower tolerance suggests better quality, this is the guaranteed actual capacitance vs label capacitance. +/-3% of 45uF vs +/- 6% of 45uF, the capacitance of +/- 3% suggests higher quality.
New to your channel. I've lived in AZ for over 15 years and this seems to make them fail every 2 to 3 years. My house is worse I believe because when they built the home they put the A/C on the ground and the A/C unit is getting blasted by the sun at the hottest time of the day. Great video! My A/C buddy just got me a new Cap and its a AM Rad. The one that failed is Genteq from Amazon from 2016.
We have a lot of power surges and some lightning strikes where I live. The last big power surge occurred while I was home and my furnace was running at the time. The power surge was so strong that it damaged my furnace fan motor and killed the compressor in my neighbor's brand new (and expensive) Carrier condensing unit. I finally bit the bullet and installed a GE power surge suppressor in my main breaker panel. I also was having problems with the breaker for the condenser unit. The breaker kept tripping and it fell into pieces when I tried to remove it. The breaker contacts looked damaged and one person told me that the contacts looked like they were damaged by lightning.
Surge suppressors really only help with lightning which is not close. Lightning has a huge amount of current flowing, which makes its own magnetic field. That magnetic field can and will cause current to flow in household wiring, which creates high voltage. All that happens past the central surge suppressor. I'm not saying it's a bad idea to have the central surge suppressor, but the closer the surge suppressor is to the equipment is protecting, the closer the lightning has to be to get past the surge suppressor, because of shorter wires which are acting like antennas. But even an unplugged appliance can be destroyed by lightning, if it's close enough.
The circuit breaker could have been old. Sometimes, the contacts inside will pit/burn causing overheating. Thus, a crumbling circuit breaker. Also, inductive loads are harder on contact points. I.e.: circuit breakers, and connection points.
What i want to know is why the old capacitors that were many times larger never failed. I know the oil was toxic in them but they were rock solid. I personally feel that the manufacturers are using these capacitors kind of like a fuse. Instead of frying the compressor or fan motor it just blows the capacitor. Cant tell you how many jobs i went to after another company couldnt fix the problem, where id pull the service panel off and see a bulged capacitor and fixed the problem in mins.
You had some useful info at the end, but you could cut the repetition and reduce the video time by 2/3 without losing one bit of information. Who cares what some people think? Tell what is correct.
My hypothesis on why some older capacitor last longer It was over designed / under rated for its voltage rating Maybe the capacitor innards like dielectric, metal plate Are simple thicker The new capacitor are optimized to close to its rating And there for do not last as long It’s like tire that are built to last 80K miles but rated only for 35K miles Just my guess
yes these days *everything* is built for controlled failure. It's bad for business to have dependable equipment and services... so we get man made chaos for high cost 😂
Had a part house guy talk about why gree mini splits eat up boards. Comes down to Chinese engineers not giving a wide enough margin for voltage. Same with run caps.
Eli the ice man.... Inductance . Voltage leads current while current lags voltage vs capacitance current leads voltage while voltage lags current.. great video
Eli - voltage leads current in an inductive circuit. Ice - current leads voltage in a capacitive circuit. The L in eli is inductive, C in ice, is capacitive. That's been a long time since I learned that.
Question since you're an expert.. If I own high end audio equipment from Accuphase, dCS, and McIntosh and I want it to last as long as possible... is it better to leave it on all the time? or turn it off when not in use ... in terms of keeping the capacitors and other components health inside.. and last longest?
Turning it off will wear the capacitors much less. Think of a capacitor basically as a time-bomb, eventually they all will fail, some are better than others.
@@dcculver2 This is why a well designed circuit will tend to have few(er) capacitors. When I open a chassis and see a sea of capacitors, my 1st thought is the performance is likely sub-par.
I was curious about the factor of 2652, in the capacitance calculation. It never occurred to me that you could actually measure the in circuit capacitance, from the voltage and current. In case I missed it in the video, or in another comment, here's where the 2652 seems to come from: rmsVolts = Impedance x rmsCurrent Impedance = rmsVolts/rmsCurrent (E1) Impedance = 1/(wC) where w is the line frequency (in radians/sec), C is capacitance w = 2 x pi x f, where pi = 3.141596, f = 60hz So Impedance = 1/(wC) = 1/ (2 x pi x 60 x C) = 1/(120 x pi x C) Using this in E1: 1/(120 x pi x C) = rmsVolts/rmsCurrent Flip both sides upside down: 120 x pi x C = rmsCurrent/rmsVolts Solve for C: C = ( rmsCurrent/rmsVolts) / (120 x pi) This gives the answer in Farads. Divide both sides by 10^-6 to get microfarads: Cmfd = ( rmsCurrent/rmsVolts) / (120 x pi x 10^-6) = ( rmsCurrent/rmsVolts) x 2652.6 Close enough.
They were not built in China. Caps 30 years ago would last 10 or more. They ones now last about 3 to 4 yrs. I check them routinely and their weak after only 2 years.. Not bad, just weak. I just replace them every 3 years on routine maintence . Replacing them is cheap insurance and may save a compressor.
I honestly thought that dual run caps fail simply because they are poorly made these days. My reasoning for this is because I come across about 5 units every summer that are 40 to 50 years old with their original, massively large, brown dual and single run caps that are working perfectly all these years later. Also back in about 2005 I started using turbo 200’s and 200x’s and I’ve never had to replace those as of yet. I absolutely love your video and learned so much. Can you answer me on how those old run caps are still performing perfectly 40 and 50 year later?
ESR will increase as a capacitor gets older. The paper inside will degrade over time due to the natural acidity in it. The voltage rating will also diminish because of the deterioration of the paper inside leading to an arc over, bloat, and bang. The hotter the environment, the faster this process happens.
I have seen many techs not use the dual capacitor when replacing. They would rather use a separate cap for the fan and single cap for the compressor. Is there any valid reason to make such a change of the approach initially used by the equipment manufacturer?
sorry. about two thirds of this is correct. a capacitor used in an AC circuit like this is NOT a storage device at all. that part of your explanation might help apprentices struggling with this concept a bit at first but it isnt right. capacitors in AC circuits is complex. in a dc circuit like a power supply it is used as a storage device to smooth the ripple into flat dc. in an ac circuit like this the capacitor is used secondarily as an AC resistance (called impedence) AND primarily as a phase shift of the current. the main winding carries current in phase with the voltage, the run winding carries current that is phase shifted relative to the voltage so that makes the motor turn. like a poor mans three phase motor but with 2 phases. if you replaced the capacitor with a resistor of the same impedance as the capacitor is providing at 50/60 Hz, the motor would not turn since the phase shift of the secondary winding is not present. in general, the real effect of a capacitor in an ac circuit is that of a frequency dependent impedance ( plus phase shift as used here) . if you doubt this, think about what the capacitors in the cross over network of of a speaker box do. they form a filter, a frequency dependent voltage divider with the inductors. Also when you are using the tong meter on inrush current it is not working properly. Use an analogue meter to see what is going on. the impedance of the capacitor and the start winding together is Z= Xc + XL = 1/2 Pi F C + 2 Pi F L. ( F = freq L = inductance C= capacitance Pi = 3.14) but the phase angle has to be allowed for. when you test the capacitor on it's own, the heating effect in the capacitor is P= V squared / Xc. it is pulling current at 90 degrees leading. not pushing it in and out. that is how it works as a power factor correction device. such as in a fluoro light or mercury vapour streetlight. the leading angle of the capacitive current (that you incorrectly say is NOT flowing) is cancelling the lagging inductive component of the motor or fluoro light current it is connected to. ( across the supply) Back to the compressor example: the current thru the series capacitor + motor inductance combo is MORE than thru the capacitor alone so it does dissipate more heat in circuit. I found this info to help with that since it is too complex to explain here. www.allaboutcircuits.com/textbook/alternating-current/chpt-5/series-r-l-and-c/ so far as what makes them fail, i think it is high temperature because they are often mounted above the compressor in a split system. the hotter the ambient temp plus the compressor temp the more likely it is to fail. notes: 1. mounting it in the airflow is good, not bad. 2. a lot of them now do not have oil inside. 3. i agree removing junctions from the cap and joining them in a terminal is better. 4. undervoltage is said to make motors pull more current. sometimes. if that is the case it MAY increase failure because of the heating effect on the mounting area. as you said anything that increases the heat dissipated inside the capacitor or it's ambient temp increases failure rate. excessive load may increase back emf and hence capacitor current and increase temp so other techs who report that may be right. read the link provided to grasp this.
I have to replace my friends run capacitor every single year, around April, just before summer season. Another thing, his compressor will still run and cool his house even with a dead run capacitor. It doesn't quite cool the house efficiently but the compressor will still start and run without overheating. I've never seen anything like it. None of his neighbors have this problem. I replaced the capacitor every April, and by April next year I have to replace it again. Start and run amps are well within norma rated range. I even added a start capacitor kit last year hoping that will help. Nope. Start capacitors fine, wrong capacitor still needs to be replaced every year.
My capacitor has failed after approximately 10 years. It's in a Rheem unit and was mounted sideways in the airstream from the factory. You're saying mounting it upright inside the enclosure area would be more desirable?
Is there a way to use multiple caps within one system to ensure 'no fail' redundancy for critical environments? Obviously, we already have redundant or backup systems in place for some applications but are there options, using caps, for those that do not have the room or the budget for more than one system.
short cycling is a good test for starter efficiency in worst case scenario. Best starter being a "SOFT STARTER" that ramps up current instead of down from 5x locked rotor spike! (figure that the rotor magnetic core needs to get charged to be polarized before stator windings electro-magnetic force can orient the rotor spin direction)
Here's one for you. Our system has a filter at the air handler which we wanted to replace. The unit was on and I was pulling on the sheet metal door to remove it and guess what was in there? A safety switch on the door so as I was pulling the door and jogging it to remove it, the safety switch as turning off then on the system vs. the squirrel cage fan. That action grounded out the compressor ! Sometimes the safety stuff shouldn't be when professionals who know what they are doing are faced with these surprises. There was no label or information on the panel to advise of this feature. Cost me big on that one.
Funny thing: .5 amps at 120 volts suggests that the capacitor is 11 microfarads. .7 amps at 208 volts suggests 9 microfarads. When I did these tests with a series pass ammeter, the microfarads didn't seem to change at all with voltage. I find that oil dielectric motor run capacitors hold a much more steady capacitance than electrolytic caps, over its entire rated voltage range. Could it be discrepancies in the clamp meter due to such low current? I wonder if the meter would read more consistent with the formula if a 70 microfarad cap was used for demonstration, just so the current was high enough for the resolution of the meter?
@@glasser2819 That's absolutely true. The current should increase exactly proportionately to the increase in voltage, and at a fixed voltage, the current should increase exactly proportionately to frequency. In this application, the frequency is largely fixed, if you don't include harmonics caused by the motor, which would increase the current disproportionately to the RMS voltage. In this video, the capacitor was NOT paired with any motor, or any real source of harmonics. The voltage varied, the harmonics did not. I would have expected a more linear change in current in proportion to the voltage, given the same capacitor.
Hi Waylon, that is a great question. At 18:42 below #5 - Compare, you will see the formula in blue letters that describes how to calculate capacitance in MFD(microfarads). The number 2652, described as a constant, in the formula is derived from other electrical formulas well known to Electrical Engineers. As I am not an electrical engineer, I do not know the electrical formulas used to calculate this constant.
If you use an oscilloscope to chart the current and voltage waveform across the capacitor, you should be able to determine the real power in the capacitor. If the voltage lags the current waveform and not superimposed as they would be in a regular resistor, the power is lower. That's basically the difference between VA and Watts, as there's a power factor involved. Since real world capacitors have an internal resistance or ESR associated with them, they will cause actual heat dissipation and start increasing the temperature of the cap that can lead to degradation.
so...could one then use a multi-value capacitor and a power factor meter or some other tester (scope) to dial in a "better" capacitor value for older systems or to compensate for wear/deviation from design?
@@douglasmontgomery6315 great reasoning to improve things up. Run caps are actually LOW capacitance to help along the RUN winding with a low current through the START winding. BEST... What kills everything is the 5x "Locked Rotor" start surge that mashes the bearings with translation forces before the rotor gets oriented to spin. FIX: use a "Smart Starter" to ramp up the start current from zero instead of surge down from 5x ! Smart-Starters save: electric power spike cost compressor: bearings contactor oversized LRA current capacitor surge stress The "ramp starter" solution is good for all *single* phase AC motors: air handlers, pumps... where 3-phase motors use a variable *frequency* ramp-up known as VFD for the same purpose of ramping-up current instead of a destructive bang surge! 👍🏻
G Lasser , thanks for the heads up on smart starter. I’ve used VFD’s for well pumps for the same reasoning you applied to the single phase A/C. Now, I’m pretty sure they also sell single phase VFD’s (some well pumps are single phase). Could they be utilized for HVAC ? Lastly, since logically utilizing a VFD type device for a compressor (really any high torque/load motor) is optimal...why aren’t they an option in residential HVAC units ? (I’m assuming they aren’t). I’m thinking the newer inverter style HVAC units don’t need a VFD due to their design.
Okay yeah I'm on 29:58 and yes that what happened to me not that long ago ... Great you mentioned that!!!!. Right on man I stayed till the end didn't know if it was gonna be mentioned or not but had to come back say it, You really have saved me a bunch of effort and money. I'm not new to this but I surely am true to this game !!!!.
Caps are rated on duty cycle. The new China caps won't even last a year or two. You should always change the cap and contact er at the same time. To my knowledge the only USA made contactor is made by Titan USA the one that is in the red white and blue box. Which are 2 to 3 times more expensive. These capacitor should last several years as the duty cycle rating is higher. The caps he talking about becareful some brands were know to catch on fire. Excellent video sir
at 4:40 you measured the capacitor current and said and wrote "start" winding. HOW? The start capacitor circuit opens up a second or so after the motor starts. So it is the run current. Then in the next slide you have 2652 x 4.2 where did the 2652 come from? The drawing is also somewhat confusing because it shows that the start winding is always in the circuit.
One thing I have noticed on Franklin submersible pumps, their CSCR control boxes have a 23uf run cap and a 108 start cap. I have tested some after 20 years of hard service and the caps were still good. The run cap is a gray plastic and I can't find them anywhere, or at 23uf. {On edit they are Aeromet, see link above} AMRAD has a 20uf US made one which I suppose is close enough. The start cap is BMI 108-120 US made and available. Anyway, point being that you can design a system that doesn't blow caps every 2 years.
A capacitor is in some ways, akin to a mechanical spring. Thermal inrush currents stress the plates and dielectric. There's also thermal expansion and contraction. You may even have some back EMF there from the windings that may be acting a bit like an inductor. They could also last longer if they had a higher rating, but then they would be of course more expensive, take up more space, etc. All engineering is about space, time, and money. Roman Roads took entirely too much time, labor, and material to build, as compared to roads that we build today. But we have to replace ours every few years, and yet some of the Roman Roads are still in use. Just my take. 73 DE W8LV BILL
Very good class my friend. I'm going to make my coworkers watch this style vids u have so they can explain to the cust easier and so they know for there own good lol.
What are you going to do tie them down and force them to watch. Customers are not interested in why parts fail. They just want to know how much it cost to replace.
In my case the capacitor in my heat pump failed because a mouse got in there and peed right on top of it. I know it was a mouse because the electrocuted carcass was still sitting across the terminals when I opened the panel to find out why it stopped running.
I come from an electronics background......... and I'm under the impression that AGE and storage conditions (heat/cold), as well as initial quality are the factors.. Let's see how this works in the HVAC world.
Inrush current when a motor starts is always higher than run current regardless of the existence of a start capacitor. On start the run winding has virtually no impedance other than winding resistance. As the motor pickup up speed the inductive reactance increases and current coming in the mains decreases to a stable run value
But when a motor STOPS, it becomes a generator and for a fraction of a second it creates high voltage back-emf. In 12v cars, a standard starter motor can throw a 600v spike back into the system. In trucks, up to 2000 volts. So it is a very brief spike, but there is a very high back-emf from the motor. Capacitors are also manufactured typically to a 10% tolerance, so if it is rated at 300vdc, it really may only be good for 270vdc. Rule of thumb in many applications is to use caps rated close to twice the expected working voltage. Same for AC units?
I learned more in 36 minutes than I did in the last 10 years.
That's when you know you are a slave and we are only made smart enough to work and not question.
jamie Webb or some people look for knowledge and others just blame everyone else for their lack of knowledge instead of trying to learn
Slamming a schroll like that can kill them. Dont teach stuff like that.
Indeed, this channel is incredibly informative.
That makes YOU a shit bag. Work harder you'll stink less.
Run capacitors fail so often, especially in hotter climates for one simple reason, the capacitors you get today are poorly made. They are insulated and cooled internally as cheaply as possible, even the ones installed in units from the factory.
@@CactusBobsPlace In NY I just replaced mine after 25 years when the fan needed replaced for the first time, the other unit still has the original cap.
Amrad capacitors are guaranteed for 5 years... I match my labor to their caps for good reason... the "el-cheapo" caps MIGHT last 2 summers... two service calls (let alone el cheapo) pay for ONE service call with an installed AMRAD... I put my name on an AMRAD for 10 years... I don't warranty them for that long... but I know AMRAD to last for ABOUT 15 years... YES, THEY ARE THAT GOOD!
The main cause is not cheap production, its the environmentalists. The chemicals to produce more reliable capacitors have been forbidden about 20 years ago, thats when the quality went downhill.
@@joskevermeulen9275 I disagree... amrad makes capacitors that last.... everything else, pretty much, does not.
@@joskevermeulen9275 No, it's cheap products. The Chinese caps are the worst. They are tiny compared to, say, US-made GE caps (back when GE owned the plant and made them here). Capacitors generate heat during operation, and that heat has to be dissipated. also, a smaller capacitor is made by using thinner aluminum deposition (which means higher internal resistance) and thinner polymer separator (which has higher loss). Combine all these cost saving "features" and you inevitably have a capacitor with a shorter life.
Brilliant demonstration! For anybody who is interested, there is an explanatory article showing the math more completely, written by Bryan Orr in AC news, titled "Testing the Run Capacitor While the System is Running", found with Google. Basically the 2652 comes from Xc=(1/(2*pi*f*C)), with 2652 in microfarads = 10^6/(2*pi*f). f is assumed 60 Hz. So, Xc = 2652/C, in microfarads. Plug that into Ohm's law E=I*Xc and rearrange to isolate C. So, C=2652*I/E. Remember that the start cap is only in the circuit for a short time at each start, so this measures only the run capacitor quality. For the brief episode when both are in the circuit, the capacitance for the two parallel lines is additive.
Older caps also were double the size to current day units, it's all a money grab now a days, but it keeps me employed so I'm not complaining
You must be young, that was the transitional period when PCB capaciters were eliminated from availability. The new non PCB caps were large until they got the design correct.
The older larger caps were always paper caps, and as such had a (sometimes poorly defined) limited life span. Modern caps are often polypropylene and "should" last longer. Of course, they don't always last longer in practice as it's fully possible to underrate them as well. They might even be more prone to heat damage than a properly manufactured (very expensive) paper capacitor.
@@mjouwbuis bingo in California caps last 5-10 years on new units, I've worked on 40+ year old carriers with factory caps still in them haha
I always look at rated voltage on a cap. If a higher rated voltage capacitor is in stock, we use them as the capacitance is only affected by back EMF, so a higher rated (sometimes 440V) voltage capacitor can "help out" in areas where voltage is inconsistent. A 220V rated capacitor can fail with spikes/lightning in area as stated. Good work Bryan!
yep exactly! Some ppl confuse voltage rating and capacitance.
The untold capacitor spec is internal *impedence*... larger caps have a lower impedance and higher voltage rating
It caused me physical pain to hear that compressor short cycling like that, great vid keep up the good work
Agreed - that was tough...
I caught myself biting my finger nails
Same here!! I once had a bad mechanical thermostat that did that sometimes and it was making that awful sound, now I know that it was running backwards. It did actually blow the start capacitor. The only time I've ever blown a start capacitor. Hard to think that it's a coincidence.
Cringe for sure
@@castirondude single phase compressor running backwards?
Great lesson. I don't care how long if be doing this business there's always something to learn . I've been here for 50 years everyday there's a new idea or approach to things I've been doing for years. Thank you
Thanks, very instructive video. My choice would be to always use a 440 Volt capacitor as long as there is physical space to accommodate it. It is worth any extra expense. The other thing is to check carefully that all connections are clean and tight. Check terminals on the capacitor, but also check the contactor and any terminal blocks. Failing connections in various locations could increase motor back EMF, causing higher voltage across the capacitor.
Old Caps were much bigger in the earlier years (50's-70's) so they held more oil to keep them cooler. Ambient heat is the number one cause of failed capacitors here. Some condensers (Ruud for example) have the capacitor in the fans airflow- you'll notice these last longer.
Pay attention to periodic potential start relays sticking.
The reason those old caps were bigger is because they used paper as the separators between the foil plates. When they went to polymer separators, they were able to make them smaller. Then they went to metallized polypropylene, making them smaller yet. But, there was a limit to how small they could be made and still have long life and good surge capacity. When you start making them as small as the import caps, there's no way they can be expected to last.
Also the chemicals caused cancer too lol like asbestos. Anything good is bad for us
I have a 1990's Rudd 2 1/2 ton with capacitors that mount into cutouts in the contactor connection box, and the cases, except for the top connections, are in the cooling airflow. Luckily, I found properly sized US made caps to replace them with, along with a new Eaton contactor.
Best video on the subject. EVER!
BTW, I always use caps with a dielectric strength of 440v vs. 377v. I suspect they're more robust in handling those pesky transients.
it's good to have extra margin around the limits
Yes, the 440v is better suited for voltage spikes, or low loading conditions.
The main reason that run caps fail is primarily the printing on the label. 30 -40 years ago it was quite uncommon for them to fail. I've found caps out of the box that were out of the 15% rule of thumb. The most problem caps have printing on the label reading "PRC" and thats a big problem
Made from chinesium or mexinesium .
@@freespirit1975 made by a factory staffed by both Chinese and Mexicans. People think it's a food place. Company name ....ElChinco
Regarding surge suppression we need to keep in mind that MOVs degrade over time due to the number of surges and their amplitude. You can have an MOV that looks perfectly fine but is no longer providing surge suppression.
More than once I've also seen them fail in a dangerous way, where the MOV was conducting enough to make it heat up and catch fire while not drawing enough current to blow the fuse. For this reason I do not use any MOV based surge protectors that have a plastic housing, I've seen power strips that completely melted down and we had a UPS at work catch fire about 15 years ago.
@@James1095 It's true, as the voltage rises across an MOV, the resistance drops proportionately. It can easily reach a point where the amount of current through the MOV will get hot, catch fire and or blow apart.
I am of the opinion that bigger is better. Some old air conditioners had huge capacitors. I don't think I have ever seen one fail. Great video
DoctorT327 you nailed it. Those big run capacitors were made with pcbs and made in the USA, both of which no longer happen. They would fail, but it was rare.
You failed to consider what happens if a compressor's connections are loose.
Consider what happens when a motor (inductor) is running with loose connections. A sudden disconnect on an inductive circuit causes voltage spikes of unlimited voltage- like your car's spark plug coil. So, age, but primarily voltage spikes resulting from bad compressor connections (or fan) cause most capacitor failures. The spikes violate the capacitor's dielectric material resulting in a short, intense heat, and then an explosion.
Check for good electrical connections at the compressor and at all connecting points in the system- the number one preventive measure! I've seen it many times.
That's something you don't hear often. Actually never. Thanks
Yeah every-time I see a failed cap, the compressor spade terminals or OF terminals are loose. I squeeze them down a little after I change the caps.
My A/C unit was actually eating run caps so I decided to check all of the wire connections. I found one of the ears was broken on a female spade connector that was connected to the low voltage coil on the contactor. Once I fixed that connector, I never had to replace another run capacitor on the condensing unit until the compressor died 10 years later. The really amazing thing is that the condenser fan motor was made by GE and it ran for almost 28 years without failure. I would oil the sleeve motor bearings every Spring.
I just replaced a cap and found a loose spade terminal. A loose terminal will cause it to overheat and burn the terminal and spade connector, wire, leaving a crispy mess and possibly a damaged compressor. Always make sure those spade terminals aren't loose.
Move to Phoenix and you'll add to your statement.
I'm an HVAC Contractor in the Metro Phoenix area. I've got units 2-3 years old with dead caps under warranty and we literally just experienced the hottest June in history and I emptied out multiple 5 gallon buckets of dead caps over the last 5-6 weeks. They are poorly made and 117 degrees plus, sustained over time fucks em' up. EXTREME HEAT kills them.
Extreme crap quality does that too.
Lived in Phoenix for decades. People don't understand just how fast caps die in that area. HVAC, Pool pump motors, car batteries, car belts, tires, etc. The heat just destroys everything. They won't even warranty tires for much over half the original warranty.
I would think that it may be likely that 117 temps ambient could end up 150 degrees under the cover if direct sunlight is bearing down on it. Possibly something to cast a shadow on the unit might help a little bit. Also 140 degree air inside the cabinet is going to affect the cap temp too.
I work in the phoenix area as well go with the turbo200 caps they do great and havent seen any fail, they also come with a 5 yr warranty
I found some made by AMRAD, all USA made capacitors.
Capacitors fail for several reasons, mostly heat and the surge cycling over time, basically because capacitors are not built to last as they once were, using inferior materials to keep production costs down. If a capacitor has been replaced in the past, if could very well be the original was replaced with a less reputable product. The voltage rating of a capacitor: is the amount of voltage a capacitor can handle on "peek demand", not what the unit runs at. The unit may run on 220-240v but the start up demand is much higher, sometimes peeking at 290v. The mfd is the charge/discharge rate of capacitor, the lower the mfd rating is, the higher charge/discharge rate. Always try to match the mfd and voltage as close as you can, if not, always go with the higher voltage rating and or a smaller mfd rating but don't make drastic mfd changes. When you are replacing a capacitor, take into consideration the age of the unit, how old is the cap and is there rust or powder present on the cap. Capacitors dry out with age, and you will get swelling, a liquid dripping or a fine powder forming on the capacitor, or an outright exploded capacitor. The powder is the dielectric drying out due to over use or just plain crappy dielectric, the liquid present is also the dielectric leaking due to expansion, the swelling is due to the dielectrics reaction with inferior materials used inside the capacitor in production, an exploded cap tells you there is too much voltage demand on the capacitor and you may want to consider a higher voltage rating when replacing it. If you replace a cap 40mfd @ 250v with the same, it will perform "as designed", you can also safely replace that same capacitor with one rated for higher voltage (40mfd @ 350 or 450v)m and it will perform as designed or better due to the higher voltage handling capability, manufacturers use absolute ratings for cost and effective production. What I mean is, higher voltage rated capacitors are going to cost more and will perform just as well and also have a longer life, but that cost may be prohibitive to the production costs, therefore manufacturers will go with the less expensive unit to save on cost. If you have a high rate of failure on this system, you may want to consider upping the voltage capacity of the capacitor, but match the mfd rating. The reason for this is due to the draw surge in electron demand on startup, the unit may now be demanding a higher capacity due to age and wear. If a unit is not maintained properly, it's demand will increase and cause a higher demand in startup voltage. As things get older the voltage demand increases, wearing of parts, lack of maintenance and whatnot. Also if the compressor HAS been replaced but the capacitor has not, the compressor and capacitor are not matched. The compressor may be a direct replacement but the physics demands may have changed. Therefore the voltage demand on startup may not be the same rating, and the capacitor voltage rating needs to match the demand. The way to figure this out is if the compressor seems to be sluggish when starting, then you know you need to lower the mfd for a faster start rate. If the compressor starts and stops a couple times or seems hesitant, it could be the mfd rate is too low and needs to be increased to allow the compressor to get a good start rate. The lower the number MFD the faster the start rate. As an example: 50 MFD will start the motor faster than a 70MFD because it takes less time to recharge the capacitor. I hope this helps. (43 years experience)
"50 MFD will start the motor faster than a 70MFD because it takes less time to recharge the capacitor" If that were true, adding a start kit, 389-524 mfd, it would further slow the compressor start, but in real life, it actually speeds up the compressor start, according to the manufacture. Even so, there is no reasonable field way to time the compressor sta, maybe in a lab....
The higher the mfd # the faster it will
Start..but it has to match the A/c
Compressor's requirements very close
My compressor Ran backwards all day. My wife ignored my advice and didn’t turn it off. It was hot as heck when I got home. I let it cool for an hour and turned it back on. It was fine and worked. The unit was already 10 years old so I called my friend and got an estimate for a new one figuring the compressor was going to die. That was in 2014. It’s still fine and runs perfectly. I’m in south Florida so it runs 12 months out of the year.
Much obliged for a comprehensive explanation of running caps. I have chastised my various HVAC Techs for replacing them (mostly as a revenue increaser) when, in fact that was unlikely the problem. The 'American made' recommendation is most appropriate!
I've seen in desert areas where the contractor put in a relatively cheapcompressor where the capacitors that fail rated to 40C in an area where it can be constantly above 45C (114F). These need to be replaced but a Cap rated to 70C (158F) to minimize it's failing.
Keep in mind that the capacitor is also a chemical based component and over time they can actually dry out which causes the capacitor value to fall over time to the point that eventually the motor startup will fail.
I think that is what is happening to my 50 HP 3 phase converter (from single) I bought the unit with 33 50 up capacitors to start 50 HP. not enough now it won't start. trying to learn to fix it myself.
@@bradjunes1610 Do you have a meter to check the caps with? If you suspect the caps but don't have a meter you can always keep your fingers crossed and just swap them out.
23:23 into the video One of my experience out in the field was a surge right after a thunderstorm I've had a few replacement because of that. Coming from my perspective it was because high voltage like you stated!. I recommend to install a 'Surge Protector'. I explained what it could do and how it works they insisted so went ahead and installed it for them.
All I can say is wow. It was very intuitive. I've been in the field for over 25 years and learned a lot on this video, but with that said the old capacitors that had PCB in them and a resistor on the terminals lasted for decades or never failed before the unit rotted out. These days it's two years on a new unit 50% of the time. So
The purpose of resistor to bleed off residual voltage in the capacitor after been disconnected from the circuit after motor start up.
PCBs, or polychlorinated biphenyls, are highly toxic industrial compounds. They pose serious health risks…
Many reasons.. surging grid volts is a biG one, no lead in the steel, or solder, the aluminum is low grade... here in FL, it's most often after lightning storms.. surge protector helps 50% of the time..
@@globedimmer8286 That's what I'm saying. It helps bleeding off the cap reducing it overheating and popping and as far as the PCB's.., I'd rather have one of them in a landfill compared to the 10 that haved popped open off a single system in a landfill.
As voltage goes up amperage goes down. The same is true in reverse. It must balance. If it does not balance heat is formed. If you have bad connections or BURNT CONTACTS which is the number one reason for capacitor failures, you will have voltage drop and heat formed. Heat is the root cause of capacitor failures. That is why very old large heavy oil filled Capacitors did not fail. They could disperse heat. Amperage draw increases heat which is a byproduct of electrical current. I spent 30 years of repairing and fixing electromechanical systems and equipment. From window units to 500 ton chillers in industrial sites. It all comes down to basics . I have held 50 year old capacitors in my hands that are just as good 50 years later as the day they were made and I have taken out bad ones that are less than a year old. Build quality is the greatest factor.
As a service technician, I've noticed some summers are capacitor hungry... some summers are fuse hungry... something tells me, the failure of capacitors OR fuses, is due to supplied power...
Very good explanation, buy one thing I am sure about is those Caps from the old units from the 70's like a GE ....those caps lasted 15 or more years.
GE makes good stuff.
Except the new GE Zoneline PTAC units. Circuit boards go bad on about 25% in first two years.
My next door neighbor has been in refrigeration for over 40 years. There were still US manufactured capacitors that contained PCBs when he started. They rarely failed... He still sees some old equipment during changeouts where the capacitor is still good. The pressure from Wall Street on HVAC manufacturers to maximize profits has driven them to "sell their souls" and purchase crappy off-shore components. My neighbor ONLY uses US made capacitors for replacement because he hates call-backs. Sadly, it's getting more difficult to source quality US made components... If you care about your customer, try to source US made 440V capacitors - ensure that all connections are clean, no burnt wires - and secure the capacitor properly (no duct tape)!
Capacitors, as they age, can develop series resistance (ESR), causing them to heat during use. Also, one should note that if the capacitor is not properly correcting for the inductive load (i.e. high amps, motor failing, wrong capacitor value), the voltage will be higher than the normal line voltage (back emf), and cause the capacitor to fail more quickly.
Nathan, so...could one then use a multi-value capacitor and a power factor meter or some other tester to dial in a "better" capacitor value for older systems or to compensate for wear/deviation from design?
@@douglasmontgomery6315 In fact, YES!
Run caps used to use pcb oil known carcinogenic in their oil, outlawed now, now they use castor oil, and don't last as long
In Florida units runtime is a lot more, its hotter longer, than other regions of country
The power surges, lightning strikes, and brownouts cause high rate of failure
Poor quality made in china caps fail prematurely, Most manufatures now use these sadly to save money, our company now only sells Made in. America 440volt rated capacitors and has had way less call backs on warranty failure of caps we install.
All the computers switched over to Japanese capacitors, much better quality. If you can get them, try looking for a Nichicon brand capacitor, I've had computers last 10 years in near continuous service without a capacitor failure in the power supplies that use that brand capacitor.
Excellent Video.
Capacitors are one of the few components used in the HVAC industry that have actually gotten cheaper in the last 40 years. Some of this is due to materials used but a large part is because I could not find a manufacturer that still does testing on production lots (I had a reason at the time). It's simply cheaper to give you a new capacitor than run production lot tests.
The number of capacitors that I've found outside tolerance straight out of the box in the last 10 - 15 years is a lot more than you might think.
C H I N A, as in made in.
Worked on a Fedders unit a couple of weeks back. Still had original cap. Manufactured 1977. Pretty sure it was a PCB filled cap.
I don't think new techs even know PCB oils used back in the day for cooling.
I haven't seen one of those old Fedders since the early 80's. We had a Fedders unit on our house in 1972 and the compressor probably died because my parents never had the unit serviced.
I think you should also think about a chattering main contactor. It's impossible to change current instantaneously across an inductor... like a motor. Some insanely high voltages can be produced if your motor contactor is having intermittent contact and there is no resistor to drain the potential infinite voltages. These (discharging winding) spikes could easily damage a run capacitor if there is no other place for them to go. When you see a burned and pitted contactor, most likely the run cap has had a bad day in that situation. If there is no suppression between motor legs on the load side of the contactor this could be another factor. The same effect makes tennis racket bug zappers produce 2750 volts from two AA batteries.
Sir Ver that’s right change the batteries in that t-stat that works only off the battery voltage to operate that contactor !
Good comments like these help me get through all the dumb ones.
All the more reason to change a pitted contactor, too.
an added note to those that fail to mount the run caps properly. These caps need that metal mounting strap as a heat since to dissipate the heat from the can to the surroundings. Failure of most electrical components is heat and moisture. I was wondering what effect using a higher or lower uf cap would have on a fan and compressor. These hard starts seem to work on out of warranty units to get em a few more years of life. How is this accomplished?
Very good theory to applied. Most caps fail because the dielectric material breaks down, accelerated by surge / strikes. Temperature is a factor, however, I haven't seen any research for long term with monitor of spikes/surge. The use of a properly sized MG set will take care of any line problems.
Run caps fail by building up internal pressure caused by heat from having high *current* combined with high *resistance* ie. impedence.
Parasitic heat generated by caps:
P = R x I2
The current being squared make caps particularly sensitive to it when internal impedence rise during aging.
Good caps are known as "LOW ESR": Equivalent Serial Resistance which grants them long service life.
Nothing magic: low-quality either builds repeat business or kills business like too many American iconic names
😂
OUT OF PHASE [23:00] : "Cap sends back"... nothing!
The cap supplied voltage and drawn current is what is out of phase.
I live in South Carolina. I service thousands of roof top units. On an average day the ambient temperature on a tar and gravel roof will be about 145 degrees Fahrenheit. On a hot day where the air temperature is 95 degrees+ I’ve seen the roof temperature up to 160 degrees. I will always use capacitors rated at 440v. And if I have unit that is in a bad location where it has poor air flow or is next to and hood fan from a kitchen I will add a hard start. That may seem like overkill but it works every time.
In Portland Oregon, I replaced a lot of capacitors each summer. They typically run between 238 and 245 volts to most residential units with bad capacitors. When measuring across the two capacitor terminals while the compressor is running, I normally get between 400 and 426 volts, depending on the capacitor size, with the larger modern high efficiency units with huge capacitors running even higher than typical. A 4 ton system with a 65 Mfd capacitor is around 425 volts across the two terminals. Sometimes I see a 370 volt capacitor in the systems.
You must use the 440 volt capacitors in Oregon, where the running voltage is normally very high. 370 volts will not survive very long.
When I worked at a University, the main building had 67 water source heat pumps running at 208 volts, and I rarely ever had a capacitor fail in that building. But other buildings with 480 volts, or the residential units for student housing had capacitor losses.
This is amazing. I had not clue that so much is taking place in these things.
The good part is, I'm a carpenter....being clueless is fine. tHanks for this great video! Love it
ha, being clueless is one thing, but in your career, being glueless, is another!
@@Dwayne_Green Well said! I need to stick to these videos....
Run Capacitor Tunes the Sign Wave... Right. Kinda like a tune up on an engine. Makes the motor run smoother with less running amps at rated speed weather cking amps on comm or run. Full circuit is made from comm to runn ie:230vac line 1 and line 2 supply voltage. Very interesting in depth post.
For a capacitor, by definition I = C x dv/dt so if you are getting large changes of voltage in a short period of time, then current will increase. The easiest way to get a high dv/dt is to connect and disconnect an inductive load, e.g. a motor. These high voltage spikes are very short, so you will never see them on your meter, but you would see it on a peak detector or an oscilloscope. It's this peak voltage that occurs for only a very short period of time that kills a capacitor, not the average voltage.
Of course heating and line voltage spikes will also cause premature failures...
Actually, you get a higher back EMF from an underloaded motor that can cause premature failures, too.
I have studied electronics in depth in high school, trade school, and in college. Your explanations of the factors causing capacitors to fail was never mentioned. We analyzed inductive & capacitive reactance. Counter or back emf (voltage) was not discussed either. This analysis applied to actual compressor winding circuits helped to clarify many issues for me. Thank you.
I wonder if excessive vibration can also lead to internal breakdown for capacitors.
Very informative. In my experience totaline seems to have the highest fail rate among manufactures. Ever since carrier started using them I noticed a big increase in failures
On the Texas Gulf Coast lightning "caused" power surges are common. I lost thousands of dollars in appliances and electronics; but I solved the problem 8 years ago. I installed an Eaton CHSPT2ULTRA surge protector on the load center. It has a surge current rating of 108 kA. Since then I have not lost anything. Best $200 I ever spent. It wont protect from a direct lightning strike like I had when 6ft of the chimney trim was blown off (nothing will do that); but it should protect for almost anything from the electrical lines.
I started adding some kind of start assist. It seems to have helped. I have had customers when looking at the history. I see run caps replaced every couple of years. I added a start assist and it's been 5 years so far. They are out in the country where surges are common.
I ended up installing a hard start kit (with the potential relay) in my A/C condensing unit and I installed a whole house surge protector in the power panel. I am thinking about adding another surge suppressor with brownout protection in my A/C disconnect to further protect my condensing unit. Over the years, I have lost a furnace blower motor to a power surge and lightning strikes have destroyed at least one of my TV's.
The basic problem is that the legacy American infrastructure does not provide 3-phase power to homes, because 100 years ago nobody expected us to be consuming $100s/month to power multi-horsepower rotating machinery (A/C compressors) all day long. This is a huge long-term waste and inefficiency. The capacitors are just a poor compromise to synthesize a second phase; it would be far better to just receive the three phases that the utility has nearby. But that would require an investment. ECM essentially converts single-phase to multi-phase, but the conversion is always significantly inefficient, and the converters are expensive, short-lived, and not ruggedly reliable, with costly maintenance.
@@devnull7550 Small world greetings, Dev! You're welcome.
you forgot - CHEAP CHINESE PARTS, AND LOOSE TERMINAL CONNECTORS, AND LIZARDS
*Ha!, ha! So right. Floridians agree on that!*
Not sure if this applies to HVAC capacitors, but one of things we do in electronics is to measure the ESR of electrolytic capacitors to get an indication of it's health. If we see a capacitor with a higher than normal ESR, then we know that it's on it's way out. A capacitor with high ESR will run hotter, which in turn shortens its life. Also if we see a capacitor reading higher than it's rated capacitance, then that could be an indication that it is becoming electrically leaky and it's probably time to start thinking about replacing it. In electronics we generally consider Japanese and American capacitors to be the best for quality and life expectancy. Not sure if you can Japanese Rubycon HVAC capacitors?
Excellent video! Those of you with thumbs down, just don't understand the principles of electricity. My question is how much coffee did you drink before you did this video?
In my 40+ year old a/c I have the original dual run capacitor. One that is oval, 11" tall and has a ground spade, too. The unit also came stock with what is called a starter capacitor in the circuit. Though even with the starter capacitor exploded(I don't know when !, I just found a few days ago when I was doing a pre-run inspection)the unit still ran well last year in this condition ! I am replacing the starter capacitor before I attempt to run it...as a matter of fact USPS informed delivery says that it is out for delivery and I should have it today !!!
spend a little on maintenance parts to save a lot on not replacing with a new short-lived unit.
Check your Starter Circuit that fried the cap... the day your compressor fails to start because of bad starter maybe one of its last days due to locked rotor high currents toasting old winding insulation.
Little homework is worth your time... AC disconnect be your friend 👍🏻
The start relay could be bad, too. It's always safest to replace both at the same time.
4:08 Its actually a fixed amount of _charge_ (hence the microfarad being used, e.g. 5 uF) that can be stored. The current is only limited by the ESR of the capacitor and the circuit its hooked to.
Yes, good word,
Techs that don’t know capacitors, how they work or why they fail, are probably the same ones that charge by beer can cold and tell homeowners they need a new compressor and not just a cap. Very good video but every field tech should definitely already know all this.
Where did you get the 2652 for the capacitance formula
These videos/podcasts are pure gold, thank you brian orr for all that u do for the industry.
The capacitor is kind of like two very large old-fashioned wire TV antennae that are folded and inter meshed with one-another, but never touching anywhere inside the container. Thus, they should have no possible way of conducting direct current inside them unless they develop a short circuit of some sort, called "leakage", which is bad news. They can also burn out and no longer conduct anything, which is a far safer way to fail. What they do is charge up the two interleaved antenna wires with a charge, on side being positive and the other negative, allowing them to soak up a rather large, for the size of the device, electrical voltage across the tiny internal gaps. How much current and voltage they handle defines their capacitance. To get a flow of power across the gap, you need AC current, since moving one side of the wires will move the other side like many tiny magnets on rollers next to one-another along each internal wire. The capacitance and voltage requirements on a capacitor tells you haw much charge can be stored inside (it can be large enough to kill you in some designs!) and how fast the frequency has to be that is being conducted to get certain amounts of power to go through the capacitor. Low capacitance devices need higher frequency AC to get enough flow, while large capacitance devices have a lot of "surface area" inside and can work at lower frequencies -- in electronic devices this controls what frequencies are allowed through various circuits and is what allows most of these things (smart phones, for example) to work. Storing charge to give a higher kick to a circuit, as being discussed in this video is the other major use.
My original run capacitor just lasted 21 years. I estimate I run the A/C for 500 hours each year, though, so that is only 10,500 hours -- far less than the 60,000-hour alleged design life. It was mounted with the connections pointing downward, so I assume this is what you mean by "upside down". Maybe it would last longer if I flip it around, but it seems like water could possibly collect on top. Nice job on the video!
When you consider the capacitor also acts as a HeatSink, Dirty Condenser, High Ambient Temperatures and Short Cycling are #1 causes. Always find out what MFD/Voltage Capacitor the motor requires. Just because the Condenser “looks” clean doesn’t mean it shouldn’t be cleaned.
after a few thousands cycles of the contactor the silver contacts become worn and arc, and the arcing induces voltage spikes that exceed the capacitors rated voltage and it pops, replace the contactor and capacitor at the same time
Thumbs up, lot of good info there. That short cycling part was killing me too!
Love your podcasts and videos! Lot's of material and information in short period. I listen and watch over and over again to absorb the information. Was thrilled to discover your android app and have been using it the last couple days just for the capacitor in circuit tests. Makes very quick work of the formulas and nice you've included percentages in the results. Replaced 2 bad caps in 2 days and was actually surprised to find both new caps just slightly outside the 6% margin.
I'm finding that the 220 Volt Systems can range from 203-247 volts input; so if you have high or low 220 input would that not change the run cap MF load? If that were true the load would be different from the rated run cap and could that cause the issue of early run cap failure?
Really well done video! I’m an EE, but no experience with motors and capacitors. This all makes perfect sense, and thanks for the tip on AmRad! I followed the link to their site and learned about their Turbo 200 universal run caps. With a total of 6 HVAC units between two houses, I love the idea of being able to cover all of them with just one cap! (Only thing is, I assume the diameter will be larger than some of the standard caps, so I may have to fiddle with the mounting.) Besides the convenience, I love that they’re US-made.
Turbo200 3x-4x more costly than standard run cap & cost has to be passed on to customer= too expensive! Great versatility in a pinch, then can go back & install correct rated cap
@@matthewclifford5824 *Wisdom*
Is a Capacitor of the same uF but different Tolerance(3% instead of 6%) ok to replace? All other ratings are the same as well.
Lower tolerance suggests better quality, this is the guaranteed actual capacitance vs label capacitance. +/-3% of 45uF vs +/- 6% of 45uF, the capacitance of +/- 3% suggests higher quality.
@@thisisyourcaptainspeaking2259 Thank you 🙏🙂
This is so good, I'll have to watch it again. Much thanks.
New to your channel. I've lived in AZ for over 15 years and this seems to make them fail every 2 to 3 years. My house is worse I believe because when they built the home they put the A/C on the ground and the A/C unit is getting blasted by the sun at the hottest time of the day. Great video! My A/C buddy just got me a new Cap and its a AM Rad. The one that failed is Genteq from Amazon from 2016.
Tripin feld jobes explain mistackinreso expals ok
We have a lot of power surges and some lightning strikes where I live. The last big power surge occurred while I was home and my furnace was running at the time. The power surge was so strong that it damaged my furnace fan motor and killed the compressor in my neighbor's brand new (and expensive) Carrier condensing unit. I finally bit the bullet and installed a GE power surge suppressor in my main breaker panel. I also was having problems with the breaker for the condenser unit. The breaker kept tripping and it fell into pieces when I tried to remove it. The breaker contacts looked damaged and one person told me that the contacts looked like they were damaged by lightning.
Surge suppressors really only help with lightning which is not close. Lightning has a huge amount of current flowing, which makes its own magnetic field. That magnetic field can and will cause current to flow in household wiring, which creates high voltage. All that happens past the central surge suppressor. I'm not saying it's a bad idea to have the central surge suppressor, but the closer the surge suppressor is to the equipment is protecting, the closer the lightning has to be to get past the surge suppressor, because of shorter wires which are acting like antennas. But even an unplugged appliance can be destroyed by lightning, if it's close enough.
The circuit breaker could have been old. Sometimes, the contacts inside will pit/burn causing overheating. Thus, a crumbling circuit breaker. Also, inductive loads are harder on contact points. I.e.: circuit breakers, and connection points.
What i want to know is why the old capacitors that were many times larger never failed. I know the oil was toxic in them but they were rock solid. I personally feel that the manufacturers are using these capacitors kind of like a fuse. Instead of frying the compressor or fan motor it just blows the capacitor.
Cant tell you how many jobs i went to after another company couldnt fix the problem, where id pull the service panel off and see a bulged capacitor and fixed the problem in mins.
You had some useful info at the end, but you could cut the repetition and reduce the video time by 2/3 without losing one bit of information. Who cares what some people think? Tell what is correct.
My hypothesis on why some older capacitor last longer
It was over designed / under rated for its voltage rating
Maybe the capacitor innards like dielectric, metal plate
Are simple thicker
The new capacitor are optimized to close to its rating
And there for do not last as long
It’s like tire that are built to last 80K miles but rated only for 35K miles
Just my guess
yes these days *everything* is built for controlled failure.
It's bad for business to have dependable equipment and services... so we get man made chaos for high cost 😂
Had a part house guy talk about why gree mini splits eat up boards. Comes down to Chinese engineers not giving a wide enough margin for voltage. Same with run caps.
Eli the ice man.... Inductance . Voltage leads current while current lags voltage vs capacitance current leads voltage while voltage lags current.. great video
Eli - voltage leads current in an inductive circuit. Ice - current leads voltage in a capacitive circuit. The L in eli is inductive, C in ice, is capacitive.
That's been a long time since I learned that.
Question since you're an expert.. If I own high end audio equipment from Accuphase, dCS, and McIntosh and I want it to last as long as possible... is it better to leave it on all the time? or turn it off when not in use ... in terms of keeping the capacitors and other components health inside.. and last longest?
Turning it off will wear the capacitors much less. Think of a capacitor basically as a time-bomb, eventually they all will fail, some are better than others.
@@thisisyourcaptainspeaking2259 True That!
@@dcculver2 This is why a well designed circuit will tend to have few(er) capacitors. When I open a chassis and see a sea of capacitors, my 1st thought is the performance is likely sub-par.
I was curious about the factor of 2652, in the capacitance calculation. It never occurred to me that you could actually measure the in circuit capacitance, from the voltage and current.
In case I missed it in the video, or in another comment, here's where the 2652 seems to come from:
rmsVolts = Impedance x rmsCurrent
Impedance = rmsVolts/rmsCurrent (E1)
Impedance = 1/(wC) where w is the line frequency (in radians/sec), C is capacitance
w = 2 x pi x f, where pi = 3.141596, f = 60hz
So Impedance = 1/(wC) = 1/ (2 x pi x 60 x C) = 1/(120 x pi x C)
Using this in E1: 1/(120 x pi x C) = rmsVolts/rmsCurrent
Flip both sides upside down:
120 x pi x C = rmsCurrent/rmsVolts
Solve for C:
C = ( rmsCurrent/rmsVolts) / (120 x pi)
This gives the answer in Farads. Divide both sides by 10^-6 to get microfarads:
Cmfd = ( rmsCurrent/rmsVolts) / (120 x pi x 10^-6) = ( rmsCurrent/rmsVolts) x 2652.6
Close enough.
I've seen extremely old capacitors last longer than the new ones
They were not built in China. Caps 30 years ago would last 10 or more. They ones now last about 3 to 4 yrs. I check them routinely and their weak after only 2 years.. Not bad, just weak. I just replace them every 3 years on routine maintence . Replacing them is cheap insurance and may save a compressor.
Daniel Roig Should've been under Carrier's 5 year warranty
Daniel Roig With Carrier it depends on the year it was made
The old capacitors had PCB oil.
After 2010-11 it's a 10 year warranty
I honestly thought that dual run caps fail simply because they are poorly made these days. My reasoning for this is because I come across about 5 units every summer that are 40 to 50 years old with their original, massively large, brown dual and single run caps that are working perfectly all these years later. Also back in about 2005 I started using turbo 200’s and 200x’s and I’ve never had to replace those as of yet. I absolutely love your video and learned so much. Can you answer me on how those old run caps are still performing perfectly 40 and 50 year later?
Planned obsolescence!
@@organicvids you are right. I hate that your right.
ESR will increase as a capacitor gets older. The paper inside will degrade over time due to the natural acidity in it. The voltage rating will also diminish because of the deterioration of the paper inside leading to an arc over, bloat, and bang. The hotter the environment, the faster this process happens.
I have seen many techs not use the dual capacitor when replacing. They would rather use a separate cap for the fan and single cap for the compressor. Is there any valid reason to make such a change of the approach initially used by the equipment manufacturer?
sorry. about two thirds of this is correct. a capacitor used in an AC circuit like this is NOT a storage device at all. that part of your explanation might help apprentices struggling with this concept a bit at first but it isnt right. capacitors in AC circuits is complex. in a dc circuit like a power supply it is used as a storage device to smooth the ripple into flat dc. in an ac circuit like this the capacitor is used secondarily as an AC resistance (called impedence) AND primarily as a phase shift of the current. the main winding carries current in phase with the voltage, the run winding carries current that is phase shifted relative to the voltage so that makes the motor turn. like a poor mans three phase motor but with 2 phases. if you replaced the capacitor with a resistor of the same impedance as the capacitor is providing at 50/60 Hz, the motor would not turn since the phase shift of the secondary winding is not present. in general, the real effect of a capacitor in an ac circuit is that of a frequency dependent impedance ( plus phase shift as used here) . if you doubt this, think about what the capacitors in the cross over network of of a speaker box do. they form a filter, a frequency dependent voltage divider with the inductors. Also when you are using the tong meter on inrush current it is not working properly. Use an analogue meter to see what is going on. the impedance of the capacitor and the start winding together is Z= Xc + XL = 1/2 Pi F C + 2 Pi F L. ( F = freq L = inductance C= capacitance Pi = 3.14) but the phase angle has to be allowed for. when you test the capacitor on it's own, the heating effect in the capacitor is P= V squared / Xc. it is pulling current at 90 degrees leading. not pushing it in and out. that is how it works as a power factor correction device. such as in a fluoro light or mercury vapour streetlight. the leading angle of the capacitive current (that you incorrectly say is NOT flowing) is cancelling the lagging inductive component of the motor or fluoro light current it is connected to. ( across the supply) Back to the compressor example: the current thru the series capacitor + motor inductance combo is MORE than thru the capacitor alone so it does dissipate more heat in circuit. I found this info to help with that since it is too complex to explain here. www.allaboutcircuits.com/textbook/alternating-current/chpt-5/series-r-l-and-c/
so far as what makes them fail, i think it is high temperature because they are often mounted above the compressor in a split system. the hotter the ambient temp plus the compressor temp the more likely it is to fail. notes: 1. mounting it in the airflow is good, not bad. 2. a lot of them now do not have oil inside. 3. i agree removing junctions from the cap and joining them in a terminal is better. 4. undervoltage is said to make motors pull more current. sometimes. if that is the case it MAY increase failure because of the heating effect on the mounting area. as you said anything that increases the heat dissipated inside the capacitor or it's ambient temp increases failure rate. excessive load may increase back emf and hence capacitor current and increase temp so other techs who report that may be right. read the link provided to grasp this.
What a thoughtful reply. Thanks for sharing this great info!
That was outstanding, increase my knowledge in half hour!!
Really great information! Every HVAC tech should watch this.
I have to replace my friends run capacitor every single year, around April, just before summer season. Another thing, his compressor will still run and cool his house even with a dead run capacitor. It doesn't quite cool the house efficiently but the compressor will still start and run without overheating. I've never seen anything like it. None of his neighbors have this problem. I replaced the capacitor every April, and by April next year I have to replace it again. Start and run amps are well within norma rated range. I even added a start capacitor kit last year hoping that will help. Nope. Start capacitors fine, wrong capacitor still needs to be replaced every year.
Check breaker connection and shut off box.
My capacitor has failed after approximately 10 years. It's in a Rheem unit and was mounted sideways in the airstream from the factory. You're saying mounting it upright inside the enclosure area would be more desirable?
It's a little bit more complicated than that but I gave you an up vote because you were mostly right
That is a solid compressor. Nice electron pressure tank.
Love the thumbnail with the turbo cap. 20 years in and I have yet to see a turbo go bad.
Is there a way to use multiple caps within one system to ensure 'no fail' redundancy for critical environments? Obviously, we already have redundant or backup systems in place for some applications but are there options, using caps, for those that do not have the room or the budget for more than one system.
There is no good reason to use single phase HVAC equipment for critical environments, but to answer your question - NO.
Wow!!! great video. You were killing me with that short cycling.
Sacrifices for science 😉
short cycling is a good test for starter efficiency in worst case scenario.
Best starter being a "SOFT STARTER" that ramps up current instead of down from 5x locked rotor spike!
(figure that the rotor magnetic core needs to get charged to be polarized before stator windings electro-magnetic force can orient the rotor spin direction)
Here's one for you. Our system has a filter at the air handler which we wanted to replace. The unit was on and I was pulling on the sheet metal door to remove it and guess what was in there? A safety switch on the door so as I was pulling the door and jogging it to remove it, the safety switch as turning off then on the system vs. the squirrel cage fan. That action grounded out the compressor ! Sometimes the safety stuff shouldn't be when professionals who know what they are doing are faced with these surprises. There was no label or information on the panel to advise of this feature. Cost me big on that one.
Funny thing: .5 amps at 120 volts suggests that the capacitor is 11 microfarads. .7 amps at 208 volts suggests 9 microfarads. When I did these tests with a series pass ammeter, the microfarads didn't seem to change at all with voltage. I find that oil dielectric motor run capacitors hold a much more steady capacitance than electrolytic caps, over its entire rated voltage range. Could it be discrepancies in the clamp meter due to such low current? I wonder if the meter would read more consistent with the formula if a 70 microfarad cap was used for demonstration, just so the current was high enough for the resolution of the meter?
because capacitor microfarad value is *fixed* the current increases with the voltage, simple!
@@glasser2819 That's absolutely true. The current should increase exactly proportionately to the increase in voltage, and at a fixed voltage, the current should increase exactly proportionately to frequency. In this application, the frequency is largely fixed, if you don't include harmonics caused by the motor, which would increase the current disproportionately to the RMS voltage.
In this video, the capacitor was NOT paired with any motor, or any real source of harmonics. The voltage varied, the harmonics did not. I would have expected a more linear change in current in proportion to the voltage, given the same capacitor.
Great video. How did you know to multiply the amps x 2652?
Hi Waylon, that is a great question.
At 18:42 below #5 - Compare, you will see the formula in blue letters that describes how to calculate capacitance in MFD(microfarads).
The number 2652, described as a constant, in the formula is derived from other electrical formulas well known to Electrical Engineers.
As I am not an electrical engineer, I do not know the electrical formulas used to calculate this constant.
If you use an oscilloscope to chart the current and voltage waveform across the capacitor, you should be able to determine the real power in the capacitor. If the voltage lags the current waveform and not superimposed as they would be in a regular resistor, the power is lower. That's basically the difference between VA and Watts, as there's a power factor involved. Since real world capacitors have an internal resistance or ESR associated with them, they will cause actual heat dissipation and start increasing the temperature of the cap that can lead to degradation.
so...could one then use a multi-value capacitor and a power factor meter or some other tester (scope) to dial in a "better" capacitor value for older systems or to compensate for wear/deviation from design?
@@douglasmontgomery6315 great reasoning to improve things up.
Run caps are actually LOW capacitance to help along the RUN winding with a low current through the START winding.
BEST...
What kills everything is the 5x "Locked Rotor" start surge that mashes the bearings with translation forces before the rotor gets oriented to spin.
FIX: use a "Smart Starter" to ramp up the start current from zero instead of surge down from 5x !
Smart-Starters save:
electric power spike cost
compressor: bearings
contactor oversized LRA current
capacitor surge stress
The "ramp starter" solution is good for all *single* phase AC motors: air handlers, pumps... where 3-phase motors use a variable *frequency* ramp-up known as VFD for the same purpose of ramping-up current instead of a destructive bang surge!
👍🏻
G Lasser , thanks for the heads up on smart starter. I’ve used VFD’s for well pumps for the same reasoning you applied to the single phase A/C.
Now, I’m pretty sure they also sell single phase VFD’s (some well pumps are single phase). Could they be utilized for HVAC ?
Lastly, since logically utilizing a VFD type device for a compressor (really any high torque/load motor) is optimal...why aren’t they an option in residential HVAC units ? (I’m assuming they aren’t). I’m thinking the newer inverter style HVAC units don’t need a VFD due to their design.
What exactly were you doing to make it short-cycle like that, without a delay happening?
Okay yeah I'm on 29:58 and yes that what happened to me not that long ago ... Great you mentioned that!!!!. Right on man I stayed till the end didn't know if it was gonna be mentioned or not but had to come back say it, You really have saved me a bunch of effort and money. I'm not new to this but I surely am true to this game !!!!.
Caps are rated on duty cycle. The new China caps won't even last a year or two. You should always change the cap and contact er at the same time. To my knowledge the only USA made contactor is made by Titan USA the one that is in the red white and blue box. Which are 2 to 3 times more expensive. These capacitor should last several years as the duty cycle rating is higher. The caps he talking about becareful some brands were know to catch on fire. Excellent video sir
Titan is the only brand I use and I will always trust him .But I’m grateful to those who use bad brands, because they give me income😅
at 4:40 you measured the capacitor current and said and wrote "start" winding. HOW? The start capacitor circuit opens up a second or so after the motor starts. So it is the run current. Then in the next slide you have 2652 x 4.2 where did the 2652 come from? The drawing is also somewhat confusing because it shows that the start winding is always in the circuit.
One thing I have noticed on Franklin submersible pumps, their CSCR control boxes have a 23uf run cap and a 108 start cap. I have tested some after 20 years of hard service and the caps were still good. The run cap is a gray plastic and I can't find them anywhere, or at 23uf. {On edit they are Aeromet, see link above} AMRAD has a 20uf US made one which I suppose is close enough. The start cap is BMI 108-120 US made and available. Anyway, point being that you can design a system that doesn't blow caps every 2 years.
A capacitor is in some ways, akin to a mechanical spring. Thermal inrush currents stress the plates and dielectric. There's also thermal expansion and contraction. You may even have some back EMF there from the windings that may be acting a bit like an inductor. They could also last longer if they had a higher rating, but then they would be of course more expensive, take up more space, etc. All engineering is about space, time, and money. Roman Roads took entirely too much time, labor, and material to build, as compared to roads that we build today. But we have to replace ours every few years, and yet some of the Roman Roads are still in use. Just my take. 73 DE W8LV BILL
Very good class my friend. I'm going to make my coworkers watch this style vids u have so they can explain to the cust easier and so they know for there own good lol.
What are you going to do tie them down and force them to watch. Customers are not interested in why parts fail. They just want to know how much it cost to replace.
1 out of 10 customers are helicopter want to know exactly what happened capacitor failure explain spot on mini batteries units.👍✌️💪🙏
@johnd4348 you would be surprised.
In my case the capacitor in my heat pump failed because a mouse got in there and peed right on top of it. I know it was a mouse because the electrocuted carcass was still sitting across the terminals when I opened the panel to find out why it stopped running.
Isn't it high voltage or high temperature? I thought you said current was limited by the capacitance...?
I come from an electronics background......... and I'm under the impression that AGE and storage conditions (heat/cold), as well as initial quality are the factors.. Let's see how this works in the HVAC world.
It works the same in the HVAC world also.
It mostly comes down to poor quality dielectric material that ages too soon .
Inrush current when a motor starts is always higher than run current regardless of the existence of a start capacitor. On start the run winding has virtually no impedance other than winding resistance. As the motor pickup up speed the inductive reactance increases and current coming in the mains decreases to a stable run value
But when a motor STOPS, it becomes a generator and for a fraction of a second it creates high voltage back-emf. In 12v cars, a standard starter motor can throw a 600v spike back into the system. In trucks, up to 2000 volts. So it is a very brief spike, but there is a very high back-emf from the motor. Capacitors are also manufactured typically to a 10% tolerance, so if it is rated at 300vdc, it really may only be good for 270vdc. Rule of thumb in many applications is to use caps rated close to twice the expected working voltage. Same for AC units?
How to run a compressor backwards, Also cheap capacitors fail more often. Good work guys nice safety glasses.