motor question

[zog]

What do you consider minor problems that myself can repair? Don't get me wrong I agree with all your testing and infact trying to put a procedure in place at my facility to test the motor when its new and periodically there after.(With an all Test Pro 31). But when I'm on the floor and everyone is screaming I gauruntee if that motor has a ground fault or even a hint of a high resistance ground fault I'm changing it because my freq drive will like it much better when I do. I can't remember the last time I changed a suspected bad motor that the new one didn't fix the problem. As for some of them having minor problems completely agree with that statement but can I rewind or fix motors no.
There are times many times I can't determine if I have a bad motor so I grab the megger or my test pro, but if I read to ground (with fluke) I'm believing I have a problem somewhere in that motor. For example a freq drive or breaker supplying a starter is tripping out fault code on drive phase a ground fault or my breaker is tripping. I go to the motor peckerhead or disconnect ahead of motor and take a resistance test from phase a to ground and read say 10ohms do I have the need to go grab a megger?

Motor, generator, and transformer insulation systems are complex systems, nto like a simple insulated LV cable. There are 3 different compoents of an inductive insulation systems that needs to be measured and evaluated, leakage, capacitive, and absorption. I have discussed these elements of complex insulating systems several times on this forurm, do a quick search (And see attachment)

As far as you developing test procedures I recommend you follow a recognized standard such as ANSI, NETA, NEMA, IEEE, or EPRI rather than develop your own.

No doubt if your fluke reads 10 Ohms you have some problem, somewhere.

 

[Strahan]

Motor, generator, and transformer insulation systems are complex systems, nto like a simple insulated LV cable. There are 3 different compoents of an inductive insulation systems that needs to be measured and evaluated, leakage, capacitive, and absorption. I have discussed these elements of complex insulating systems several times on this forurm, do a quick search (And see attachment)

As far as you developing test procedures I recommend you follow a recognized standard such as ANSI, NETA, NEMA, IEEE, or EPRI rather than develop your own.

No doubt if your fluke reads 10 Ohms you have some problem, somewhere.

I would not develop my own. The All Test Pro 31 is based on EPRI and we have record sheets ready its just putting everything in motion. Not sure if you are familiar with the all test pro or not but it is capable of taking a series of impedance based tests.
I have run into prblems with motors that I had no explanation for and at the time if I would have had the all test pro I may have been able to answer those problems. Yes nothing showed up with my DMM nor did anything show up with a megger. I'm merely stating that obvious problems such as a ground fault in a winding or phase imbalances between windings can be detected with a DMM.