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Re: Xfmr question

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>


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.

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.