Re: Megger test.

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Jim Lux by way of Terry Fritz <twftesla-at-qwest-dot-net>" <jimlux-at-earthlink-dot-net>

A megger test checks the integrity of the insulation by putting a highish
(several hundred typically) voltage between the winding and the case and
verifying that the resistance is several megohms.

If the windings have the right DC resistance (low), and it's not shorted to
the case, the odds of it being good are great.  

Will they let you test it on site, before purchasing?  Hook the 220V line
to the HV side of the transformer and measure the voltage on the LV side.


Tesla list wrote:
> 
> Original poster: "Mr Gregory Peters by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <s371034-at-student.uq.edu.au>
> 
> Hey guys,
> 
> As afore mentioned, I priced a reconditioned pole pig at $1045
> Australian. However, they will sell me an unconditioned unit for $500
> Australian (about $250 US). They say the only test they will do on the
> transformer is a megger test. What is a megger test? Is this a reliable
> indication of the transformers integrity? Would you guys suggest saving
> for the reconditioned unit or buying the "as is" unit? I figure I can
> buy two of the "as is" uints for the price of 1 reconditioned unit, and
> the chances of both being duds are minimal. What do you think?
> 
> Cheers,
> 
> Greg Peters
> Department of Earth Sciences,
> University of Queensland
> 
> Phone: 0402 841 677