Electric Motor Phase Shift Explained | Capacitor Start Motor
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- เผยแพร่เมื่อ 26 ก.ค. 2024
- This is Electric Motor Phase Shift Demonstration and Explanation. Phase Shift explained and demonstrated. In this update video I demonstrate how the Phase Shift works in this capacitor start motor. This is how the magnetic force is formed to start the rotation of the capacitor start motor.
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I restore the 70 year old ac electric motor. I am restoring a cement / concrete mixer from the late 50's/early 60's. This part is the repair and restoration of the ac electric motor. The ac electric motor is a 1 hp, Single Phase, 60 Hz, 1720 RPM, Capacitor Start, 110/220 VAC, 12.6/6.7 Amps.
The mixer was picked up by my father in the early 60's. The cement / concrete mixer has seen a lot of work and abuse from many members of the family. It is time to get it running again. I will start with the GE Electric Motor then move on to Jack shaft, Yoke, Drum, Brake.
Lots of work to do.
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#electricmotorphaseshift# electricmotorrepair#cementmixer - แนวปฏิบัติและการใช้ชีวิต
Thank you for making the video it was very helpful.
Glad it was helpful!
Whoaaaaa Rando, my brain nearly overheated on this one. Regardless, I will risk what grey matter I have left and will continue to watch your videos as they are enlightening, informative, educational and entertaining. Your a true renaissance man.
Thank you Uncle Buck. Love that movie. Take it easy on the brain cells, I tired to make this easy.
Man Randy... Electronics too? You do it all Brother!
Thanks Clint.
Cool to see it in action. It will be interesting to see how much it moves when it has the load applied.
Yep, I will redo the test with load. We will see what the change is. Thanks Brian.
My first thought at about 1:20. Has there been a retest under load Posted?
We are feeling right a home watching you share your findings through the meter Randy. We enjoyed.
Lance & Patrick.
Thanks Lance & Patrick.
Great demo of what's happening with the electrical. I don't have an oscilloscope, so I use thumb rules for my capacitor choices, if I can't read the start cap info. If I get a medium start, with correct voltage and amps, with no overheating, then I'm good. Haven't burned one up yet. I do like the info you get from the scope.
Can be a very useful tool. Thanks Vernon.
Very good Randy. I have had a scope on my list for years. Someday. Thanks
Fun to use, can help troubleshoot stuff. Thanks Randy.
Thanks Randy I was able to understand what was going on and put everything in perspective. Which is not always the case with electricity
Thanks A Z. I hope this helps, trying just to keep it simple.
I really liked this segment on the motor restoration an excellent presentation. I don't have a good knowledge of this subject, but your explanation of it makes good sense and is very understandable to someone like me with very little knowledge on the subject. Thanks for sharing.now I know what out of phase means and how to adjust.Have a blessed day!
Watching in Alabama
Good deal Anthony i hope this helps. Thanks.
What about the current side of the coin? Voltage lags in a capacitor. Meaning, that it lags behind its current. It takes time for the cap to charge, and during this charge, the voltage rises over time. The current is at its maximum value the entire time the voltage is rising, due to charging the capacitor. This is where voltage and current also get out of phase. So not only do you have 2 voltage waveforms out of phase, but you have 2 current waveforms out of phase. And one of each waveform that isn't in phase with anything. Or does the inductive load lag the current back? Or is 60hz low enough of a frequency that it wouldn't matter? I would be curious to see a 4 channel scope with the other 2 channels using current probes. Would also be interesting to see the sum of them.
Nice demo about showing phases on practical app... 🙂👍
Just a little hint I use here, to avoid hunting focus on the camera, find the manual focus adjust and set it on the main subject, then, you avoid the hunting problem.... 😉
Thanks Pierre. Yeah I forget sometimes to set it to manual.
I was drinking my morning cup of coffee.
Clicked on your channel.
Instantly I was back to my engineering college days!!
AC/DC Analysis...
Will there be a Quiz ???
:)
p.s. I use the same Fluke Scopemeter....just a newer Model.....Batteries are still available...
Thanks Stuart. No quizes. I should get a new battery.
Try here for a compatible replacement....
www.battery2batteries.com/fluke-95-scopemeter-battery-pack-replacement/?gclid=CjwKCAjwk93rBRBLEiwAcMapUeepQM1-DKdi4hZXBpq5tY1QaTMfdLVpEKfj2It0-DHSIGnOUUYxJhoCbjoQAvD_BwE
Thanks for explaining that! 👍
Thanks Alan.
I didn't know that adjusting capacitors could affect the time alignment... Now I know!
Thanks Greg. Learn something new everyday, good for the brain.
Good demo / explanation Randy. Handheld scopes are super handy, don't have to worry about grounding out your circuit.
I had everything grounded. Try this on a ship which is running an active cathodic protection system. Thanks Bill.
@@RRINTHESHOP Yeah Randy, I was sloppy with my terminology. I meant with plug in scopes and the low side of each channel ground referenced, very easy to forget that and put that clip on the probe in the wrong spot in the circuit. Not that I've ever done that...
@@billdlv Oh yes common ground is important for ref. and no ground loop current.
Scoutcrafter sent me over and glad he id. You have a lot of great content I will be enjoying Subbed!.
Thanks Lee, about 500 videos.
Morning Randy! Good demonstrate! 0
Thanks Craig. Havin coffee now.
Great video! I understand that adding larger capacitance to the start cap will give more starting torque.The real question of trying to get the perfect opposite shift would be for a motor with a run capacitor also,with it energized the whole time the motor is running and would be optimal to be ideal,since I am dealing with that problem now.I need to get an oscilloscope I guess.
Yep get a scope, these days they are cheap. The best way to tune a motor. Thanks for watching.
Interesting pointer. Use #102 for a genuine Randy Richards scribe. :)
Great pointer. thanks Wes.
I have always wondered if a capacitor creates an off (main ) phase wave to act more like dc current or 3 phase. Obviously it adds a boost but it would have to precede the main phase. Comments?
Great Videoio think I'll like your channel
Thank you Larry.
I want to run 3Hp 3 phase motor with two phase only using capacitors to get 120 degrees shift change for third, how much value of capacitors I have to use and how to connect starting and running capacitors please explain ...
Thank you
It is worth it to buy a VFD. Doing it with just caps is not good or easy, you will have unbalanced loading of the phases and will probably eventually burn up your motor. VFDs are cheap today, easy and work well.
Great video! What is the ideal phase difference? 90 degrees?
That is ideal.
This is a really nice explanatory presentation, Randy! How do you like the Fluke o-scope?
It works well. I am sure newer units have better resolution on the LCD. Thanks Tim.
Is there something about the Fluke oscilloscope that made you decide to use that unit? I use a Rigol DS1054Z Digital Oscilloscope. It's a 50MHz, 4 channel color o-scope with many bells and whistles. It's not battery operated, but it only cost $350.
I have had this cope for over 20 yrs. This was what I needed at the time. There are many better and great option out there now.
I assume adding more capacitance will increase phase shift. How do you calculate the new capacitance value, or is this a trial and error process? Also, does increasing load reduce phase shift?
Yes depending on load you may want to adjust the capacitance for optimal performance.
What happens to input amperage and output amperage after the adjustment?
Very little. More about better starting torque and lower temps.
@@RRINTHESHOP It should be noticable, can you do these tests under load ?
It looks like the run winding and start winding are physically mounted in the stator 90 degrees apart... If that observation is correct, the ideal electrical phase shift for that motor would be 90 degrees. +/- 20% seems like a valid tolerance to me.
Well this test was not under load and in a loaded condition this could change. I will test it after it is installed to see where it is at, then determine if I need to change the caps. Thanks Thomas.
Question. Would there be a situation where you don't want maximum staring torque? For example to give you a softer start and less strain on some mechanical part?
Ted I think in this type of motor you will always want full torque. The longer it takes to start the more heat is generated in the starting windings and this happens fast, high current flow. They do make motors that do soft starts.
Most interesting. It is always interesting how the capacitors can change the phase shift. I know there is a lot of this when a person is making a rotary phase converter and trying to get all three of the three phase amperage draws the same. You said 108 degrees was in the ballpark.
On starting a single phase capacitor start motor. Is there a certain degrees of phase shift one needs to make the motor start most efficient? Thanks, Tom
Yes 90 deg. is the optimum. This will make the Power Factor 1. In this type of motor it is not so critical since this effect is only used during starting and will effect the starting torque. In a 3 phase motor this is very critical. Due to inefficiency in a 3 ph motor it will not run at synchronous speed, and thus be out of phase with the generator of the 3 ph power. So the PF is usually around 0.7 to 0.8, and with capacitance added you can correct the PF to 1.0. This will then make the generation and power usage system more efficient, and save energy. I will have to setup this demo again after the Cement Mixer is back up and running with a load on the motor, we can see what the phase shift is and then see if we need to adjust the capacitance to get the motor torque and PF to 1.0, max starting torque. Thanks Okie-Tom.
If you go to the cursor menu and turn on phase A-B, then turn on marker for phase. It will calculate it for you. You dont need the markers but it helps to confirm you are in the correct spots for measurements.
I will check that out thank you for the great help. Thanks Colin.
Mine is a fluke 97. I know many of them had that but im not sure what all models. You do have to watch so that the markers are approximately the same positions on the wave forms if you want it to be pretty accurate. Some times i move the left cursor to make it read from the next wave. Depending on what channel it may read backward. But its a pretty handy feature.
Yes I checked, mine will do that. I will give it a try soon. Thanks Colin.
@@RRINTHESHOP if it reads around the 250 area, you can swap the a and b channel leads, or after pressing the cursor button. Press the left soft key, that changes the source from a to b. Also press the channel a b button. Then press the up key a few times, that turns on averaging and will prevent the phase degrees from fluctuating.
It took me quite a while of reading and trying to figure out how to match a capacitor to my hermetic compressor i used to retrofit my ac recovery unit to high pressure r410a. I kinda thought i figured it out. Then i found your video and it helped me get it just right. I got the compressor used and was sent a 50uf. I have plenty of caps laying around so i tried other values. Turns out 40uf gets me at 94 degrees phase shift while running and still good quick starts. Thanks for the video, im good with my scope but wasnt completely sure if i was measuring right until i watch you.
The representation shows to me that you have 2 phases of a 3 phase waveform. It would seem to me that is exactly what you want in a single phase motor boost started by a capacitor and a rpm switch.
Yes this is correct. Thanks workaholic53.
very old motor you turn on the motor then press the start button until the motor is near run speed when you take your finger off start it settles down
Yep. Thanks Bleu wolf
😃👍. 🇺🇸
Thanks Scout.
Now I sort of feel a bit out of phase.
More coffee should correct your PF.
I was phased out long ago
@@docokd7oco443 Not to far out.
Now you've gone and done it! Who cares about speeds and feeds when you have phase angles and voltage probes! I see you now with your best white lab coat complete with pocket protector explaining inductive reactance as the ways on your machines rust slowly in the background.
Just wait. My coat is Gray. Thanks Michael.