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

Jesse

Looking at it another way, the motors they are controlling
are kinda a 3 phase motor with a built in phase convertor
(the capacitor). So you have to look at your motor and
see it it has a starter switch that cuts the capacitor out.
Usually if there is a switch (centrifugal), there can be
jus a starter winding or a starter winding and a capacitor.
If it just has a sarter winding, I would not think that the
variable speed board would work. If it has the capacitor
it might. I would sure want to talk to the company and they seem
to encourage communication. I would have the motor cleaned
up and the end bell off so I could tell them what is there. If
you find anything out, please post it.
bob mcknight

>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 thi
>
>

These look like capacitor run motors. and look like the same motor
used without the variable speed feature. The ones I have seen on
power tools would not have high starting loads. It looks like a 4
to one speed turn down is what they are advertising. This is the same
turn down that they state on similar systems that do use pulse width
modulation with DC motors.

The HVAC systems are another item -- they run the air handler fan
and
are not capacitor motors -- these are becoming common in newer
HVAC
systems .

My question is really about the tool motors. i haven't bought one so
I haven't really looked at the control and I am not a EE. just an
old Chem E.

jesse


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