[Boatanchors] Baking moisture from power transformers

[Dave Brown]

If you know the current rating of the secondary, and have a variac, short 
the secondary via an AC anmmeter and  power the primary through the 
variac-increase the primary voltage till you get the rated secondary 
current-this will happen at very low applied primary voltage- and let it 
cook from the inside for a few days. Once the core has been warm for a day 
or two its probably OK to stop the cooking and test at full primary 
voltage-after removing the short on the secondary!
 73
Dave
ZL3FJ



----- Original Message ----- 
From: "John King via Boatanchors" <boatanchors at mailman.qth.net>
To: <boatanchors at mailman.qth.net>
Sent: Tuesday, December 23, 2014 5:14 AM
Subject: [Boatanchors] Baking moisture from power transformers


>I have  a plate power transformer that has been stored inside the shop and 
>not exposed to moisture other than the normal high humidity of the 
>Louisiana climate. I would like to be sure that it has not absorbed 
>sufficient moisture from the inside atmosphere to endanger its' likely of 
>developing a short.
>
> I am considering baking it in my wife's (K5MOL's) kitchen oven. I am 
> interested in your experience with residual moisture removal from stored 
> transformers. I have read somewhere that 150 degrees  might do the job 
> without damaging the insulation. What temperature have you used and for 
> what period of time? Your input based on experience or referral to the 
> information on the internet will be appreciated.  Thanks and 73, John, 
> K5PGW
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