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Re: Microwave Oven Transformers (MOTs)
Hi Mr. McCreath
Tesla List wrote:
>
> Hello Gavin:
>
> For the sake of the explanation I'm assuming that your two MOT's are
> of the same make and model. That being the case, connect the two
> cores together solidly, both electrically and mechanically. This is
> the point that will be solidly grounded to your TC ground when you
> connect things up for use.
>
>
O.K., two questions:
Actually, I have two different MOTs, one is higher in power than the other,
does this pose a problem. Or is it because the winding directions of the
coils may be different, making phasing difficult to know? If it is that
latter, is there a way of finding out the phasing? Does it matter if I get
the phasing wrong, will it destroy the MOTs?
The second question is with regard to connecting the two cores together, are
we talking about some real metal work here or just a sensibly sized metal
straps or something?
> With the primary terminals are facing you, label the terminals one and
> two on both transformers, making sure they are the same on each. Then
> connect terminal 1 of left transformer to terminal 2 of the right, and
> terminal 2 of the left transformer to terminal 1 of the right. This is
> done so that the two primaries are in parallel but 180 degrees out of
> phase, which is what you want.
>
> With the above hookup complete, apply power to the transformers with
> either a variac or a 100 watt light bulb connected in the hot power
> lead to limit the current. Using EXTREME CAUTION and well insulated
> leads, you should be able to draw a pretty good arc between the two
> H.V. leads, one from each transformer, if all is working as it should.
> If you have a meter with a high enough range you should measure about
> 5000 volts between the two secondary leads, or twice the voltage of
> one transformer by itself.
>
With reference to the above question regarding phasing, and assuming that if
I get this wrong the whole thing does not bow up in my face, would the
following procedure work?
Connect the two primaries together in parallel with a 100 watt bulb in series
with the connected-together primaries. If the bulb is dim, then the phasing
is wrong and the primary leads of one of the MOTs need to be swapped round to
correct the phasing.
>
> As far as current limiting is concerned, you can use either a resistor
> or an inductor, or even a combination of both, to keep the primary
> current under control. Some of the fellows use a third MOT with the
> secondary leads shorted together as an inductor. Just connect its
> primary in series with the hot lead of your power cord.
If you connect together the secondary leads of an MOT, does this not turn the
transformer into a resistance? The magnetic field in the core generated by
the primary would induce a current in the secondary, which in turn induces an
opposing field back into the core. If this is so, then the device is no
longer an inductor as it is unable to store energy in the form of a magnetic
field. If this is the case, all you are left with is the DC resistance of the
primary coil? Or am I wrong?
>
>
>
> 73, Weazle, VE3EAR/VE3WZL
>
> Listening: 147.030+ and 442.075+
> E-mail: weazle-at-hurontel.on.ca
> or ve3ear-at-rac.ca
> Web site: www.hurontel.on.ca/~weazle
Thanks again for your help, but I may be back with more questions.
Regards,
Gavin, U.K.