Re: Microwave Oven Transformers (MOTs)

At 07:27 AM 05/02/2000 -0600, you wrote:
>Original Poster: "sundog" <sundog-at-timeship-dot-net> 
>Hi!  MOTs must be ballasted, because unlike NST's or OBIT's, they
>don't have current-limiting shunts that keep the core from
>saturating and dumping as much current as it can till either the
>wires burn up, the breaker/fuse goes, or someting else blows up
>(read "Your Cap!")

Hi Sundog, all

This conflicts with my own experience.  My twin MOT supply with voltage
doublers is running unballasted on a 220V/20 Amp circuit, and it has never
tripped the breaker.  Likewise, I have tried the same power supply with no
voltage doublers and no ballast, and it still didn't trip the breaker.
Also, I have tested a few 115V MOTs that did not trip a 20A/115V breaker
with the HV lead shorted to the core and the primary plugged into a regular
wall outlet.  The MOTs I tested in this way got hot, but did not burn up or
damage anything.  I agree that they are not designed to run in a continuous
short-circuit condition, but some MOTs regulate themselves better than
others.  Even so, if you wish to run more than one MOT on a single 115V
circuit, then ballasting is required.

My $.02 worth,


>-----Original Message-----
>From: Tesla List <tesla-at-pupman-dot-com>
>To: tesla-at-pupman-dot-com <tesla-at-pupman-dot-com>
>Date: Monday, May 01, 2000 10:13 PM
>Subject: Re: Microwave Oven Transformers (MOTs)
>>Original Poster: Fucian-at-aol-dot-com
>>Then why must they (MOTs) be ballasted?