Re: [CAD_CAM_EDM_DRO] variable speed on single phase capacitor motors

From the wiring diagram, it looks like this works on motors
that I would call a Capacitor Run motor. We have capacitor
start motors which provide for pretty good starting torque. We have
capacitor start and capacitor run motors which provide both good
starting torque and good torque when running. This looks like
it would work with the capacitor start, capacitor run motors, but
not with the capacitor start only motors. It looks like the
circuit they are selling is effectively changing the capacitance
run value of capacitor. So It looks like it is applicable to a load
that would be similar to a Fan blade (maybe a blower to).

I am not sure how this would apply to a specific application.

When you want to reduce the current of a fan motor, you reduce
the amount of air that it is pumping. This goes counter to many
peoples thinking. When I take a blower out of a furnace to use
for a shop blower, if I just set it out on the floor and turn it on,
it usually will draw too much current. If I put a piece of plywood
and block off the air inlet on the side opposite the motor, it usuall
brings the current down below the rated amps.
It is this type of system that this control i designed to work in.
I would want to keep an ammeter in the circuit while I was
experimenting.
bob mcknght




I have recently noticed that some inexpensive tools are using this
type drive. I had thought they were using DC motors but this doesn't
seem to be so. This has to be very cheap to do considering that it
seems to be used on very inexpensive machines.

I have been using DC PM motors with pulse width modulation control
for
varispeed but this seems to be more interesting.

For motor hook up look at analog control info at:
http://www.varidigm.com/products/prods_vsm.asp

I have a HVAC system that uses a specialy adapted 1/2 HP GE motor
but
this is not the ame thing I am describing.

Does anyone know these systems?
jesse



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