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How do I use this megger tester?

jackorocko

Apr 4, 2010
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So I found this contraption in my grandfathers old belongings. It has some stuff on there about insulation resistance.

If I understand this correctly, it is used to test like the windings in a motor or maybe even a transformer? The thing is old, so it even has a crank on it to produce the high voltages I am assuming. Is something like this still relevant to test motor windings?

I got about twenty or so motors sitting on a back shelf and this would be a good way to test them for keeps or the trash heap, right?

http://www.amazon.com/gp/product/im...mage_text_z_0?ie=UTF8&n=1055398&s=home-garden Can it really be from the 1930's?
 

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Resqueline

Jul 31, 2009
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Nice find!
Yes, it's for testing insulation integrity, and yes - it's still a perfectly good piece of test equipment!
Though the design may be from the 30's I would believe they were produced unchanged right into the 70's.
It will produce a fairly stable test voltage over a wide range of cranking speeds, but around 1 rpm I think is a nominal speed.
You can check the voltage output with your DMM, and the megger should show 10-11MΩ in the process.
In addition to ground insulation it may be a good idea to check the inter-winding insulation on motors with separable windings.
You can check house wiring (mains power off) and appliances (unplugged) too.
 

jackorocko

Apr 4, 2010
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I will have to actually get it out and try it now. Supposedly this is the "meg" model, which according to that pamphlet will produce 500V. Neat little piece of american electrical history.
 
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