Search results for query: *

I don't think surge testing is very good for field testing. The rotor has a big influence on the shape of the traces. I think it is much better for shop tests, or at least when the motor is disassembled. I won't even address the destructive aspect of surge. Look at PdMA.com and see their...

I don't think vibration would have much, if any, effect on effeciency of a motor. It is more a symptom of some other problem. Some examples are eccentricity, imbalance, misalignment, rotor bars, bearings, looseness, etc. These problems will have an effect on motor life and possibly performance.

Using the PdMA MCE tester gives the DA as well as the PI numbers in the one test. It is possible toget a good DA and then the PI not be good. It also shows the profile I mentioned above. We rely on this more than any other aspect of our predictive program. Check out their website. www.pdma.com

We have found that the ratio number is less important than the shape of the curve plotted by almost continous reading. The curve should ideally be like a capacitor charge curve. It should be relatively smooth with no major negative going spikes. These show insulation breakdown. You can have this...

A universal motor, AC or DC, is reversed by changing armature polarity in relation to the field. Just swap the two brush leads. There is the possibility that it may not be designed to run in either direction.

TO electricpete: Drop me a note to cdhawk@eastman.com and I'll send some good examples.

There should be no dip at all. Touching the lead insulation will cause a dip but this is a result of a change in capacitance to ground and of no concern. Barring this, I would look at anything 10% or more. The overall megohm value would play a part also. At 3,500 meg, a 10 meg drop is too bad...

PI is a good indicator of insulation health, but you need to go a step farther. We look at the profile of the entire ten minute test. There may be insulation breakdown as indicated by dips in the charted values and still have a good ratio (2-4). The test made by the PdMA tester plots a chart...