[Boatanchors] Baking moisture from power transformers

[Rodger Singley]

I use the same method as Dave except being the conservative sort I limit the secondary current to around 80% rated.  Have a fuse somewhere near the expected current draw in the primary, if the transformer is bad it won't save it but it may keep you from a house full of smoke and transformer smell since most of us don't babysit the transformer the entire time it is cooking.

No matter what baking method you use don't "cook" the transformer in a sealed box.  Hopefully it isn't really damp but you do want any liberated moisture to leave the area rather than creating a transformer sauna.

Before you even start this process check and correct any insulation issues where the leads enter the housing.

Rodger WQ9E

-------- Original Message --------
> From: "Dave Brown" <tractorb at ihug.co.nz>
> Sent: Monday, December 22, 2014 2:39 PM
> To: boatanchors at mailman.qth.net
> Subject: Re: [Boatanchors] Baking moisture from power transformers
> 
> 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
> 
>