Re: Xfmr question

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Mddeming@xxxxxxx 

In a message dated 2/7/05 10:33:52 AM Eastern Standard Time, 
tesla@xxxxxxxxxx writes:
Original poster: "Christopher" <cpfortun@xxxxxxxxxx>

Hello......

I was wondering if a transformer can be damaged if you reverse the power
connections. Hooking up the 120 wall outlet to the secondary and hooking
up the primary as the output? All comments are appreciated.
Chris

Hi Chris,
It depends on what kind of transformer you're talking about. A step-up 
transformer, (NST, pole pig, HV power supply, etc.), usually no problem, as 
long as you don't try to run 30 Amps through an HV winding with wire sized 
for 30 mA. A step-down transformer, (door bell, model train, LV computer 
supply, filament transformers, etc.) Big Problem. Step-down transformers 
are rarely over-designed or over-insulated. Putting 120v on a secondary 
designed for 12v means the turns per volt is way off and will get very hot 
from core saturation, if the insulation does not break down, melt, and/or 
short out first.

Hope this helps
Matt D.