Maximum MOT`s power for long, reliable operation and life - how much is it?

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Original poster: Grishka <ghome@xxxxxxxxx>

There`re lots of articles in Internet, when people use MOTs as TC power supply.
In all cases they draw more than 1 kW from one MOT, they say, operational
time is short (some minutes)... I then decided to find out, how many watts
can give us one MOT in a continuos condition of operation.
I`ve recently made rather simple experiment - I`ve connected in series 10
incandenscent lamps (60 watt one piece), MOT was working 45 minutes, it`s
temperature  became 76 degrees! But - my mains voltage was only 206 volts
instead of 220 - and let`s imagine, what could happen with this transformer at
full 220 volts?! A friend of mine (father dest) has tested such transformer
with NO LOAD - after 20 minutes of operation transformer`s core was so hot,
that couldn`t be touched by fingers for more than 5 sec! (mains voltage was
226 volts, air temperature in the room - 28 degrees).

According to these facts I have some questions:

1 - does anybody know, how good is the wire insulation in MOT (varnish)?
That is - what temperature does this varnish can face without considerable
decreasing its life time?

2 - does MOT worth to be put into the oil? Can we consider oil as "a good
cooler"? Think about inner layers of HV winding - we can`t measure temperature
right there...

3 - In future I want to run my TC during 5 minutes continuous (minimum! - it`s
better 10 or 15 minutes) with pauses not more than 10 minutes (with total
runtime about 1 hour). What power could we draw per MOT in such condition
without overheating? What is overhreating for you (see question #1)?



--
Best regards,
 Grishka                          mailto:ghome@xxxxxxxxx