Urgent Help - PM 940M down. Motor issue

[Sticks]

Testing more stuff. Getting leakage coming from the motor on the Z2 and Z2 legs. 31Vac. Originating in the motor. U1 and U2 is constant power 120Vac. Might be normal....Might be a bad inertia board in the motor.

 

[Sticks]

The Or [V1] is 380v when the motor does finally spin up, which is a direct connect to the run capacitor. Wonder if that is what blew that one.

 

[B2]

Here is the motor tag

Of course. Single phase. Sorry, I was not thinking single phase and of course that is why you have the starter capacitor!

 

[Sticks]

No worries. Now it's just to hurry up and wait for precision Matthews to either get my email or see this thread and somebody chime in.

 

[Sticks]

SOLVED

Precision Matthew shot me an email this morning. Needed to pull the motor and clean the contacts on the centrifugal start switch inside the motor.

That fixed it.

I can't edit the thread title. If a MOD could open that back up and Mark it as solved it would be appreciated.

 

[markba633csi]

Good news! We still don't know why the original cap blew but for now let's assume it was just an infant mortality
Edit: I think I see the reason- the voltage rating was too low

Kinda makes me wonder why the switch needed cleaning on such a young motor tho
Unless possibly some contaminant was left on the contacts- cosmoline, grease, varnish, etc. who knows

 

[Larry$]

contacts on the centrifugal start switch inside the motor.

Most common point of failure on a single phase motor! Another good reason to use 3 phase!

 

[braddr]

Also worth noting that the most common cause for accelerated electrolytic capacitor failures is heat. If you've been pushing the motor hard and causing it to get hot a lot, that can hurt their lifetime.

 

[MikeWi]

Doesn't really apply to the start cap though. It gets beat up hard, but only for a second or so, unless the switch sticks. Once that happens, say goodnight Gracie.

 

[braddr]

The cap's usage pattern is only at startup, but it's affected by the running temp of the motor and the environment it lives in in general.