Start Capacitors & Run Capacitors for Electric Motors - Differences Explained by TEMCo
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- เผยแพร่เมื่อ 4 ต.ค. 2024
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What's the difference between a start capacitor and a run capacitor? Can you use them interchangeably? See why these two types of capacitors cannot always be substituted for one another.
Learn about bleed down resistors here: • Start Capacitor Bleed ...
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TEMCo offers many related products including: Soft Starters, Motor
Starters, Electric Motors, Phase Converters, and more.
View our full lineup, models & pricing here: temcoindustria...
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Very well done! All tutorials should be this easy to understand. I have absolutely no doubt now how to identify a running or start capacitor or how they shouldn't be used. Thank you!
This is one of the best UTube videos I've seen. You explained the capacitors & their uses very well PLUS you blew one up for everybody to see how they fail. Yeah
Sorry talk very fast with no clear , enough text for explanation
and it's an ad
@@dhidhi1000 uyi
"IF" the clock on the back wall was accurate, you did this in one take. Until you started blowing stuff up, you just kept rolling without a bleep or hiccup. Sometimes people aren't just watching what you do, but how you get it done as well. Very good on both counts. Congratulations.
I can’t tell you how many capacitor videos I’ve watched. This video gave it to you in layman‘s terms it shows you a start capacitor had to run capacitor and how they work. Very good.
Thanks for the feedback - we'll definitely keep the audio quality in mind for future videos.
Why DC motors does not need these kind of capacitors???
Your video on differences between run and start capacitors is very good. What you did not mention is the larger capacitance will deliver a certain current for a LONGER (time) as required. One can obtain the same current level with a small capacitance but the time constant is much shorter, and this will not work! In reality, current delivered by a capacitor is determined by I=V/R. Remember there is a time constant! For example a voltage of 100 volts across a capacitor with a 1 ohm resistor across capacitor will deliver 100 amperes (time constant not taken into account,) Capacitors can more or less be inspected on performance by using an ohm meter on the megohm scale, across a discharged capacitor. Reading should be in the megohm or higher, Basically an open circuit. For quality, apply the operating DC voltage across the cap. to charge. Then install a DC Ma meter to view current flow into the capacitor. This determines the number of DC ohms of this capacitor, ( ohms =V/I ) and shows the power factor. The higher the Ma flow into this capacitor, the worse this capacitor is or is rising to 1, power factor. Power factor is PF = R/Z. It should be 0, or almost no current flow indicates a good capacitor! (R is extremely high.). FYI, there should be no heat detected at any time. To increase capacitor life, add parallel capacitors at the same voltage but adding to required capacitance only , not over. For example a 100 uf cap. can be split twice of 2 x 50 uf or more. Splitting the current demanded by the motor capacitor is always easier on a cap. when multi units are in parallel, and this results in added capacitor life! You might need hundreds of amperes for starting and the small R of the capacitor adds up when delivering lots of amperes, resulting in heat in the capacitor, a no, no.
Great video but one thing to note.... When recording the video I think you had the sound levels volume to high for your microphone., that is why the volume is kind of popping up on a lot of you words. thanks.
Excellent! Just what I needed to keep from blowing myself up. Got the new "start" cap installed and motor running.
Compact and clear yet propper information to get going with, great video which helped me forward
Excellent demonstration. Good info on the differences.
you have provided me knowledge and one day I will reciprocate by buyimg parts from you. that is how the world should be.
i took hvac class about 8 years ago ,,,thanks for your video ,interesting . love to learn
Great Video!!! thanks for explaining the two different types. I know nothing about them. Installed a start capacitor in a run setup by mistake and it blew up right away hahaha. Now I know that it needs a run capacitor to work. Thanks again, saved me from buying a new motor for the bandsaw
Some capacitors are 1000+ mfd, though many have low capacitance ranges as well. In your case, you could easily use a run cap in place of a start cap.
Some capacitors are built with a "Pressure Sensitive Interrupter" design that causes them to fail before internal pressures can cause serious injury. The one we showed is designed so that the top of the capacitor expands and breaks internal wiring.
Best explanation ive watchd out of 25 vids. Thank u
Thank u for the info sir, this is exactly what I need to know for testing a start capacitor.
You are very well spoken, thanks for the vid!
Matt's Shop was
Alex Bob Network Are you not still well spoken?
Great work if you have any more heating or air conditioning tips I like to see them very knowledgeable
I have an older AC motor that is 240v and runs two capacitors. I went to fire it up and one of the capacitors smoked up. The other one was entirely cool and I noticed it doesn't seem to have any juice in it. The smokey one was spraying heck all over the place.
My suspicion was that one capacitor went bad and it wasn't able to get up to speed and thus the centrifugal switches weren't able to kick in and it smoked the other one. Does that make sense or am I completely off the mark.
Also for replacing these would I need 120v capacitors since it's one capacitor on each 120v circuit or would I need two 240v capacitors? Mine also don't have the bleed down resistor on them, not sure if that's necessary for the newer ones or not. It's an old saw from the 20s but the motor is definitely newer.
Stumbled across these videos from your ebay auctions. Figured I'd see what you guys have to say on it.
I would like to see the voltage meter readings when you are checking the capacitors in this video. Thank you
Awesome video! Thanks alot for taking the time to make this! Funny the background behind you, because this is exactly the info i needed to complete my RPC and get my shop back online!! Thanks again! Awesome!
These videos need to be re-recorded with a better mic. Amazing information, but physically painful mic quality. These peaks actually hurt to hear.
Never listen to audio on youtube. Mute your device and click on the CC button. I also click on the gear icon for the settings then the Subtitles menu and change it to a larger font. I like to change the Video Speed to 1.5. This totally eliminates the sound of wind, passing vehicles, and most importantly annoying music.
Okay tell me a bote the run capacitor. How you know the size of capacitor to use on your 3phase motor?
Just what I needed at this moment. Thanks for taking the time to share.
If this is the wrong place/channel for this question, I apologize upfront for not being technical in this area. I have a situation I need help with involving Start-Up and/or Run Capacitor(s). I think.....
Situation: When my 6,500 Watt (peak) house back up generator is used to power my home in power outages, my A/C will start slowly and run as the generator slows way down, but the generator recovers after the A/C fully starts up (pump and fans). The A/C will run powered by the generator for whatever time is required for the thermostat setting. The rest of the house circuits can be turned on (Frig, lights, .....) while the A/C is running and all is well and the generator does not sound overloaded or toggle its breaker off. However, once the A/C turns off when the set temperature is achieved, it will not cycle back on without the generator throwing its main 220VAC breaker which shuts everything down. Then, with ALL circuits to the house off (except A/C), and the generator breaker reset, the generator will struggle to restart the A/C and most of the time will throw the 220VAC generator breaker. While during this condition, I can turn on everything/every circuit in the house and the generator will power everything without issue until I try to start the A/C and the cycle repeats. (I know to give the A/C n Generator the best chance to restart is to turn off all the other circuits, my point is to show there is nothing else out of the ordinary while in this condition)
I think I need a larger Startup Capacitor for my A/C Condenser (pump and fan). How would I figure out what type/size/capacitance, ......Capacitor to purchase and how would I identify the terminals such that I can swap it out with the existing correctly?
Please note: I do not need a lesson in the generator peak/run and house demand (load). I am that technical (for a mechanical guy, but this is Magic Smoke Stuff and so I am in the deep end and barely treading water). For review: 1.) The generator runs the house with no issues with the A/C off. 2.) The generator runs the house with the A/C starting first and the rest of the house load added after the A/C starts the First Time. 3.) The A/C will seldom start the Second Time even if all the house loads are turned off and only the A/C is connected to the generator. 4.) Other than this Second Start (or anything after) failure of the A/C running on the generator, the A/C works flawlessly on-grid power as does the rest of the house.
Thank you in advance for any help.
What you are needing to add to your A/C unit is known as a Soft Start capacitor. It reduces inrush capacity needed from your generator upon the startup of the AC's condensing unit, which likely requires a substantial current draw when engaged and until it reaches its normal operating running speed, which likely takes a few seconds. This increased draw happens for large enough of a draw and for long enough that it trips the generators breaker because it overly taxes the generators system to a degree that it would either A; bog it down to a point at which it would stall the engine or B; overload the generating capacity of the core itself and start heating to a degree where the internals could become damaged or fail completely. Just look up "A/C Soft Start Capacitors" or "A/C Soft Start Systems" and there will be a wide array for you to research and choose from. Hope this info helped and good luck with your project
An educational promotion; don't see that very often in youtube land - well done :)
AC capacitors are non-polarity specific, so it doesn't matter which side you connect the wires.
Great Video. Simple and concise.
Good day, Sir can Í asked the correct value of capacitor for 10hp motor 3 phase that can run single phase 220vac. Thank you Sir
Great video! One question: You mentioned that run capacitors have a 100% duty cycle so they can remain in the circuit. I want to use these capacitors for a pf correction project on an induction motor, but as my pf will be changing, i need to provide nearly constant switching in which the caps are introduced and taken out of the circuit. Is this safe to do for run caps, or should i use a different type of capacitor?
Thank you in advance!
Can you explain how you are running an AC motor on DC power? This will help us understand more about your set up.
All VFD‘s that run AC motors is actually positive negative DC that mimics ac
This isn't something we specialize in, but you can look up info on power factor correction using capacitors.
I bought a couple of your run capacitors and noticed no country of manufactur on label are they made in China? HVAC Industry having lots of problems with China made caps don't last. I now have gone to Genteq and have better luck.
Thang you for that sharing sir.
Thank you for watching! Glad you found it useful.
2:41 consider this when considering adding a capacitor to my living room bathroom exhaust blower motor to stop it from getting stuck on start up.
Very informative, kind of a shame the audio is bad quality. Gotta watch those clip levels.
Hey man.. Great video, my motor is humming, I swapped over a capacitor I had in shop, it started motor but cap exploded hahaha after a minute, I will drop a link for my problem, it is a pdf file with all parts listed, I think it is a run capacitor I need, it's the the 66uf 50Hz.. One on the list thanks you my good man
If a motor calls for a 5mF run CAP will the motor be damaged if you use a 7.5 or 10mF run CAP?
Great video. If the centrifugal switch is not releasing would this cause for the motor to draw higher current. My motor runs approximately 3amp without load and about 4-6 amp with load. I have found when the switch is not opening the current jumps to 22amps. The problem was a dead capacitor which I feel was the cause from the centrifugal switch not releasing when motor on. I find that the switch only doesn't release when the load is on the motor soon as I put some load after turning the motor on and off eventually the switch doesn’t release and the current jumps higher. The switch looks clean and no damage. Any help to diagnose is appreciated. Cheers
The switch should open just before the motor reaches full speed. Off the top of my head, here are a few common causes: Loose connection. Voltage falling off from undersized or too long supply cables. Bad motor bearings causing increased startup drag. Soot at the point of contact on the switch contacts (look for a small black spot) if yes, clean with file or sandpaper.
Tip ... never use headphones 🎧 in full volume for this video specially starting.
Judging from the capacitance, it appears to be a start capacitor. Start capacitors typically have a range of capacitances, while run capacitors give a single number. The values on start caps also tend to be higher than those on run caps.
Is it a good idea to install a start capacitor if compressor run capacitor keeps blowing? Could this keep the unit working for a while until it can be replaced?
Great video. Very well explained. !!! Very educational
You said a capacitor should be about 1.5 times the supplied voltage.
I had a pump that ran on 120 volts but the capacitor said 300VAC.
Does the hp of the motor matter for the necessary VAC ?
There are no markings on it but I think this motor is around 1/2 hp.
Question 1) Was that capacitor VAC bigger than necessary ? (1.5 x 120v = 180)
I messed up and let it run after it pumped out all the water.
Once I unplugged it, it would no longer start or run unless I spun the impeller by hand, then it worked fine.
Question 2) Can you clarify and explain to me if it was a start or a run capacitor, or combination ?
It says only 8 micro farads, so I guess maybe that makes it a run capacitor.
So then I guess sometimes a run capacitor is all that's needed to get the motor 'to start' ????
Because...why ?
I’m confused about you usage of “duty cycle”. I’ve only been exposed to the term regarding a DC square wave signal at a fixed frequency and duty cycle refers to how much of the wave is “high” vs “low”. Never heard it used discussing AC signals. I would appreciate any feedback.
I'm impressed and I don't know anything. I am experimenting with running an AC 230volt washing machine motor on DC 12volts and upwards. I am pleased with the results. However I need more start torque. Can I achieve this with capacitors and if so how do I go about it. Many thanks for the video. I learnt something I did not know today.
Both original and replacement run capacitor are same 12.5 MFD 440/370 VAC but new replaced blower motor has 7.5 MFD listed . Still good ? Seems fine , it working
I wanted to know the power supply voltage you were using we understood it was AC but is that a 120 plug that you hooks to the capacitors directly I want to know it's capability can you put a wall outlet directly to one of those running capacitors?
Run caps could be use for PF correction. It would be important to be sure that the caps that are out of the circuit at any given time are drained before being reintroduced to the circuit.
Do you have to change capacitors with exactly the same one or is similar or close capacity ok
My AC went out. My intent was to do the electrical checks, but it started out with a dead mouse on top of the capacitor. I cleaned all the debris, then did the checks for the compressor which was fine as was the relay and controller voltage, leaving the capacitor. I couldn't find any shorts on the capacitor but it is the last item to prove out. It did have a bulge on the top. So I ordered it. I get it tomorrow. Question: was it the mouse that may have cause the capacitor to fail?
I have a 240v 3 phase 7.5hp 5.5kw induction motor for a heavy duty mixer and would like to run it on single phase as i do not have 3phase connection at my location. will i be able to convert it to single phase with cap or i wont get the amount speed from the motor?
Is the voltage spec on a Start (or Run) cap an absolute value?
In other words, will a 250v rated cap work ok in a 110v circuit, given the µF is correct ?
Thank you for that sharing sir.
How do you know what size compasotor to replace the compasotors with if there's no label or writing on the old compasotors and there's 3 compasotors on this air compressor and how do I find out what one is the start and run on this compressor?
Are common and run terminals on single run capacitor interchangeable since there are no markings?
Thank you. Very informative video
I do understand the main differences between a run capacitor and a start capacitor and their purposes but what I don't understand is why did replacing the 5uF run capacitor on my spa circ pump motor fix its problem of not starting?
Thats all good, but how to identify a run verses start cap. Say you have and you don't know where it came from, how do you tell if it is a run or a start by just looking at the cap.
I have a 220 VAC sanding machine motor, replaced Now starts slow and take time to gradually get to proper speed (around 5-8 sec). Is it the wrong replacement mtor or starting capacitor? Should I increase the capacitance? Appreciate your help.
Good Video. Very well done. In your demonstration are you just throwing raw AC power across the caps with out any type of a buffer in the circuit? Thanks.
Thank for the info sir.how much is prize of running capacitor?
Thank you for commenting, and we're glad that the video helped you out. If you have any other questions or ideas on future videos, let us know!
How do I find what value start capacitor to use to replace an unmarked one? The motor is 230vac, 12A, 2hp, 1ph. I can not find any info for the 40 year old motor.
Have an old Craftsmen 3/4 HP motor. Obsolete parts. It has a capacitor mounted on top. I have to say its a start. Not sure. Its dual voltage. Old cap was 233-280. Old cap part # was 37211 no info available any more.
Not sure if that was correct replacement. Having problem finding any information on this saw motor.
Old model Craftsman model is 113-12060.
Some blogs say it was an old Emerson motor made for Sears.
Old cap was shot. Just want to make sure I insert correct size.
This was my dads saw , trying to restore it. Any help appreciated.
Just make sure that the new capacitor:
1. Capacitance is roughly the same: 233-280uf
2. Voltage is same or higher than you are powering your machine with. If you are using 120volts. Cap should be at least 120 volt rated. Higher is ok.
3. The new capacitor will fit in the can on top of your motor. Smaller is ok.
Outside of that, you should be good to go! Good luck!
Very well done.
Thank you
A great tutorial easy to understand and concise. Thank you.
They make a great filter capacitors on the cheap for tube amplifiers and last a long time
Looks so good, high quality built
To sum this up when you connect caps in series you add the voltages but you divide the mfd by the number of caps in series. Caps in parallel you add the MFD and the voltage remains the same
What's the different systems of a single phase motor when the start capacitor goes bad and run capacitor goes bad?
Maybe you can show all kind of capacitors and what are they used for...i want to know the various kind of capacitors
Hi and thank you for your help. I was going to take the motor apart but thought an easier test. I snipped off one of the cap wires then turned on the small band saw. The motor just hummed so I quickly turned the motor but it would not start. I then reconnected the cap, turned the motor on and it ran. While it was running, I removed the jumper from the cap and the motor slowed down a bit. So I think this is a run cap. Have I diagnosed this correctly? Thank you.
I need a lil help.. I am trying to get a pool pump motor to run off of my dc to ac inverter and just hums and then the inverter shuts down. I think if I add a start run capacitor to the circuit it should work fine. I am hoping .. it’s a 120 volt 12 amp 60 hrtz motor. Which start/run capacitor do you recommend. I am thinking a CBB 65 will work. But don’t want to blow the motor.. any suggestions ?
I have a 10hp 230v three phase air compressor I am wanting to run on 230v single phase what start capacitor and run capacitors would you recommend to generate the third field?
I have a Lakewood floor fan that runs slowly or not at all on low settings.It does not seem to be a lube problem. Any ideas.
Hey thank you for making this video. ;)
100% educational and professional all the way through.
Not sure if this is what I'm looking for. I made an Arduino powered motor by replacing existing electronics with my own circuit, but recently it intermittently doesn't start, just hums. The only way to get it working is to knock it hard against something and then it seems to run okay. Have done something wrong like run too high a voltage through it? It's happened on 2 of my motors now.
So just to clarify, you can replace a start capacitor with a run capacitor if it has sufficient micro-Farads? For example I have a 8uF start capacitor, I can replace it with a 8uF run capacitor?
Hi will a microwave capacitor 1.1uf 2100vac 50/60hz can be charged by 12 volt battery ? Can it be used to between the battery bank and inverter to not let the battery bank take the brunt of electric initial draw. Saving battery. ?
I was looking at Baldor 6" Bench Grinders. They have approx. 14 different models! One of the descriptions says: Built for heavy duty grinding, powered by 1/3 hp Baldor PSC type motor (except 612E & 662E which are split phase)
What would be better for that type of bench grinder, a (PSC) Permanent Split Capacitor or a Split Phase motor?
Is one harder or take longer to start? Do you have to spin the wheels to get it going?
I have a rather large electric motor that needed a new cord wired on when I bought it. With that done, the motor ran but had no torque. I bought it to spin a table saw but it would not start. I could spin the blade and it would barely run. One capacitor is a 110v run/start and the other is a 220v run capacitor. I'm thinking this should be wired as a 220 volt motor? Thoughts??
Sir What is the size Capacitor for 7.5 hp Electric Motor Pump. Start and Run
I suggest you check what came on the motor from the factory, different strokes for different motors. Problem is you might not be the first guy to change them and the one in it might not be right.
Well worth watching.
@TEMCo Industrial Power
My start up capacitor on my compressor is only 31.5uF at 400v (2 terminal) if i buy a much bigger uF rating ie (400uF) would it make my compressor start easier.
Mine at present doesn't always start up every time, sometimes it buzzes upon start up and freezes,if i spin the motor by hand it will start up, is my start up capacitor faulty and would it cause these start up problems??
We don't have specific instructions on repairing this, as they can vary depending on motor manufacturers.
You might want to just try getting a capacitor of matching values, as they're fairly inexpensive.
Thank you! Great video!
What capacitors should I connect to the 400Watt generator, any suggestion please .
I am using capacitors 8 micro farad and as soon as I plug in the light. the power is gon generator is 650 watts
Great video!
What ohm and power is the discharge resistor you used?
I have a couple carpet blowers that run off and on. Would this be a capacitor problem. They run for ten minutes and stop for five minutes
If replacing a capacitor, if not 1.5x the line rated voltage, what voltage can it be or does it need to be exactly the same?
am using a schultz angle grinder, it has two capacitors, now I have a problem with a big capacitor from it which has some drums inside(capacitor with drums inside), what type of capacitor can I repress it and can a capacitors from a capacitors Bosch grinder work in it ????
16 uf is generally not enough to start a motor, but CBB60 SH seems to be a part number for an Amico brand start capacitor.
My hvac fan motor runs for about 15 seconds then shuts down. Is that indicative of a bad run capacitor vs a bad start capacitor or did it sound like some other problem altogether? Thanks!
Sounds like a run capacitor problem, or there could be a thermostatic switch on the motor that has gone bad.
Thank you for the reply. Perhaps I should open the motor and look for an centrifugal switch.
I have a grizzly dust collector motor wired for 220. Seems the capacitor is bad. Opened it up and it’s a 300mfd, 120VAC capacitor.
Am I right that that is the wrong capacitor? Possible that the motor was rewired for 220 and the capacitor was not changed?
I got the unit used.
No problem. Yes, if there's a centrifugal switch, you would definitely know for sure whether or not it is a start capacitor.
really do like your videos. I have a compressor and need to use a generator to run it. Vendor says don't use a generator. Is there a percentage increase on the size of the start capacitor that would make the combination of motor/generator a little more friendly and work together a little better? This is what I have now, Microfarad Rating: 324-389 165 volts. Thanks!
Running on single phase?