DD Motor Running Rough

hias9

1 kW
Joined
Jul 11, 2018
Messages
422
Today I had rough running and higher than usual drag on my 3kw DD motor (with Statorade+Hubsinks). I push up to 20kw bursts through it and allow up to 135 degrees Celsius at the windings (thermal foldback starts at 110) and motor was close to 135 on this ride.
However it is not the first time it has seen this temperature.

I have attached pictures I took after opening the motor today. The rough running and drag was caused by those wooden sticks which had moved. Also the yellow insulation layers seems to have moved at some areas.

Anybody already had the same issues?



 
I used 120 degrees Celsius limit at the windings in the past. After that I gradually increased up to 135 degrees. I was worried more about the magnets (rated 120 degrees), but noticed no Kv change at all.
Yesterday after opening the motor I removed all the wooden pieces (except near there hall sensors where they are kept in place by glue). Motor runs fine. Looks like the yellow insulation layer got soft and the wooden sticks got loose because of that.
Maximum temperature reached yesterday was 128 (temp sensor at the windings).
Maximum the motor has seen was 137 degrees, but only for a short time and already a few months ago.

If you look at the windings, some of them are dark. So it looks like the heating at the windings might be a bit unequal. Probably potting would be a good idea when allowing high motor temperatures.
 
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