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Electric Motors Winding and Repair Electric Motors Winding and Repair Discussion


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Old 04-13-2021, 11:41 PM   #1 (permalink)
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Default Re-Wound Winding Testing - Help

Hey Fellas,

I rewound my Quantum 2820-880KV to a DLRK-Delta & in the process of testing to find my new KV I cannot get a stable HZ measurement. I am wondering if I wound the stator incorrectly. The voltage is the same & stable across all three phases, depending on speed. I cannot get a stable frequency measurement across any of the three phases.

I know that I can use a RPM detector so show motor speed, but I was trying to avoid purchasing a $40.00 meter (Harbor Freight) for this task only.

I am following the instructions for measuring motor RPM unpowered given at: https://www.radiocontrolinfo.com/bru...ing-motor-rpm/

Once this value is known I was going to use this formula for KV value: https://www.radiocontrolinfo.com/bru...e-a-motors-kv/

I am using a corded electric drill with a listed RPM of 2500. My Multimeter is a Greenlee that measures my 120 voltage at 60.2 HZ so I know its working correctly.

Does anybody know whats going on?

Thanks!

I didnt take any photos of the stator before I terminated my windings. (I wish I had now....) Attatched is the best photo I have.
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Old 04-14-2021, 12:40 AM   #2 (permalink)
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After doing more digging on this forum I think I might have found my problem.

I was reading that I needed to megger the windings @ 1K so I grabbed my Fluke 1520 and went to work.

I megger the leads to motor shaft and found a direct short. I have included a photo of it. As I was winding the motor I was checking for shorts against the stator so I am not sure what happened here.

But when I put 1000V to it they failed (All three leads failed the same test, same spot) Mabey I got to froggy with the winding wire, I will tear it apart tomorrow night and see what is going on.

Photo attached showing the fault as the test is being run. (little purple spot in the windings)
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Old 04-15-2021, 10:49 AM   #3 (permalink)
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Hi D.e.,
If its a parallel delta you can come straight out from under the hood with no leads cut and finalize the connection of starts and ends at the inverter connection of UVW. This usually makes it very "airy" and open under the hood which is a good thing. What a nice diagnostic tool the megger is. As you become a more experienced winder the less you'll probably use it. A single coil winding system make this all easier. You can fit more Cu with no transitional wire for the dual layer, and theoretically u can replace a bad coil without a full tear down.
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Old 04-15-2021, 03:27 PM   #4 (permalink)
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It may be that you created the short when pressing the iron onto the stator piece. Good luck troubleshooting. It may be a good to check for shorts after each step of disassembly. It can be difficult to locate otherwise
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Old 05-06-2021, 11:18 PM   #5 (permalink)
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Default New Problem.....High KV

Hey Fellas,

I started over with this motor. I coated the stator with thinned JB weld, rewound the stator and proof tested each of the windings as I went. Varnished and terminated the windings in a delta config. Now when testing with my electric drill the motor is operating correctly & I am able to get stable frequency for KV verification.

My math is telling me the rewound motor KV is 1985. The original motor KV with 7 turns of multi stranded wire was 880. Now I am stumped. I was under the understanding that Multi Stranded turns count the same as solid wire. It should have been very close to the same KV value.
DLRK wind Delta Termination

Thoughts before I rewind this motor...AGAIN!

Math Used:

RPM = (120 X Frequency) / # Motor Poles
2453 = (120 X 204.4) / 10

KV = RPM / (V X 1.3433)
1985 = 2453 / (.92 X 1.3433)

Motor Specs: https://www.gravesrc.com/quantum-out...820-880kv.html

THANKS!!
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Old 05-07-2021, 11:16 AM   #6 (permalink)
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It does not matter so with that much variant your calculations are off somewhere. You move fast IMHO .Id never varnish anything until the motor is where I want it in Kv etc.

Regards
Hugh
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Old 05-08-2021, 12:39 AM   #7 (permalink)
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Thanks 1BOHO,

What is the method that you use to calculate KV and I can give that a shot and compare?
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Old 05-10-2021, 04:20 PM   #8 (permalink)
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I always test wind with thin wire eg 0.4mm to confirm winding scheme, termination, and kv. It is a good practice and takes maybe half hour or so.
You should also measure kv directly on the esc before you disassemble it to confirm your drill test.
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Old 05-19-2021, 01:59 PM   #9 (permalink)
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Quote:
Originally Posted by Damn_encode View Post
Thanks 1BOHO,

What is the method that you use to calculate KV and I can give that a shot and compare?
Take a source with a known speed like a drill and measure the Voltage rms with your digital multimeter then multiply this number by the square root of 2 then divide this number by the known source rpm. That will be a fairly accurate measure. The test wire run test can have some minor error because each persons controller or settings may be different and that can change the terminal speed. The bemf voltage on the other hand should be wind consistent based solely on a known rpm like a drill.

Sorry for the late responses. My son and I've been playing with our Volvos lately. Were building the single cam 8 valve "family cars" with more power than a gran Turismo Maserati ever had.....




The 8 valve family car that cannot handle corners according to the experts ruled the world touring car championship 5 years in a row. You may wonder where was Bavarian Motor Works and all the others high end sports cars in this class... 2nd place that's where. We do more than sit behind pc's running our mouths all day with no real action like Anakin and Kunzke do. We multitask not make excuses! They need sleep and have to cater to mommy....no way they can keep up with me.

Regards
Hubert
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Last edited by 1BOHO; 05-19-2021 at 02:21 PM..
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