Re: Transformers

At 04:30 PM 2/7/96 +0700, you wrote:
>>From SROYS-at-radiology.ab.umd.edu Wed Feb  7 15:21 MST 1996
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>To: tesla-at-grendel.objinc-dot-com
>From: "SROYS"  <SROYS-at-radiology.ab.umd.edu>
>Date:         Wed, 7 Feb 1996 16:23:37 EDT
>Subject:      Transformers
>What is the best way to try to see if a transformer (pole or potential) 
>is good using only a DVOM?  Is it just a matter of making sure the 
>terminals aren't open circuited, and that the LV and HV sides aren't 
>shorted together (assuming they're really not electrically connected), 
>or is there more to it than that?
>Steven Roys (sroys-at-radiology.ab.umd.edu)
>The above proceedure is a basic test for dead shorts and open windings,
however that test will not ensure that the transformer is good, unless you
have the factory data on the dc resistance for the primary and secondary
windings. It is posible to have insulation breakdown causing a few shorted
windings. This would not show up with an ohm meter unless you knew the exact
factory dc resistance of the winding. If you have access to a "megger" or
meg-ohm meter, you can test for insulatiopn breakdown between the primary
and secondary windings. These devices apply a high voltage to the circuit
under test, and will cause faulty insulation to break down under test, thus
indicating a short. Otherwise.... pour the power to it and look for smoke !!!!

Jim Leonard