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SRSG Voltage and Current
Original poster: "Terry Fritz" <twftesla-at-uswest-dot-net>
I hooked up a voltage probe and current transducer to the input of both of
my rotary gap motors. The waveforms are at:
The waveforms are very similar. Both motors are 1/4 HP. The big coil gap
uses a Magnatek and the small coil gap has an A.O Smith motor both with
The big gap with its larger rotor and ferrite covered electrodes draws more
current as shown in the graphs but the waveforms are still very close.
This is good for designing a phase controller using John Freau's idea that
would work well on any 1/4 HP motor. The current waveform is a bit messy
for modeling but an series RL circuit should be close for general testing
by computer. However, startup and other difficult model things will have
to be worked out on an actual system.
The concern about the variac and capacitor going uncontrollably resonant if
the motor load is not present, may be solved by simply placing a fast blow
fuse in series with the capacitor (or being sure the motor is always in
circuit). However, much more thought needs to go into all this.
I don't know too much about motor modelling or control especially with sync
motors and in the dynamic (startup and loss of sync cases). So any
thoughts are welcome.