Anyone use a Megger (Megohmmeter) ?

[Buzzie8]

I want to test some Baldor drive motors that have failed before I throw them out. I am also having a problem with a VF drive were I get a Ground Fault error and I want to check and see if it is a bad motor before I just start replacing parts. I bought a cheapie $125 megohmmeter at Grainger today and want to test the motors tomorrow. I was told by my Baldor dealer to check each phase of the three phase on each leg by keeping the motor wired for low voltage (220) and taking wires from VF drive off. In essence remove one wire from each wire nut that goes to VF but keep the legs going to the motor connected. For instance, wires 2 and 8 remain wired together for low voltage and probe these to ground. I am confused because in a video on you tube it looked like they tested each wire individually that went to motor. Learning something new everyday. Any help greatly appreciated.

 

[sparkey]

I disconnect all wires and test each wire to ground. If you leave some of the wires tied together you are still basically doing the same test. You are still looking for current leakage to ground. Make sure you disconnect the drive. You could also just remove the 3 phases at the drive and meg the 3 leads to ground. This method will also test the wires going to the motor.

 

[mac]

There seems to be a wide variety of these meters out there. They range from a couple hundred to over a grand. For what we do is there some spec that it should be able to measure?

 

[Greg Pack]

You could also just remove the 3 phases at the drive and meg the 3 leads to ground. This method will also test the wires going to the motor.

I have done it this way before and the motor tested bad. However, when testing the same motor at the pecker head it tested OK. The problem went away when I re-stripped and reconnected the wires in the pecker head. As a result I don't consider the motor bad unless it tests bad at the pecker head.

 

[Greg Pack]

There seems to be a wide variety of these meters out there. They range from a couple hundred to over a grand. For what we do is there some spec that it should be able to measure?

I use the supco m500. It is cheap and has idiot lights- Perfect for me! It's one of those things I don't use often, but bad a motor can cause some crazy problems on the water wizard.

 

[bjo]

I have done it this way before and the motor tested bad. However, when testing the same motor at the pecker head it tested OK. The problem went away when I re-stripped and reconnected the wires in the pecker head. As a result I don't consider the motor bad unless it tests bad at the pecker head.

I use a megger , a cheapie , but I'm sorry . What is a pecker head as it relates to an electric motor?

 

[MEP001]

What is a pecker head as it relates to an electric motor?

It's the box on the motor in which the wires hook up.

 

[Buzzie8]

I used my new megger today (not sure of actual brand name) $125 from Grainger with no gauge read outs but idiot lights. Worked great old motors that created problems checked bad and new motoros check good. Should've had one of these tester 7 years ago.