Mike Henderson
04-01-2009, 2:25 PM
I'll make these notes for whoever wins the Gast vacuum pump. A friend of mine had this exact pump (I believe) and I wired it up for her. It's a bit of a trick to wire it up.
This pump was designed for industrial control. The motor is a single phase induction motor but it does not have the internal centrifugal switch that a regular single phase induction motor would have to switch the starting capacitor in and out of the circuit. So what you have to do is rig up some switching arrangement that puts the starting capacitor in the circuit when you're starting up the motor but disconnects it after the motor starts. (the notes that came with the motor indicated a timed switch which would remove the starting cap a certain number of seconds after power was applied)
What I did was use a DPDT toggle switch with three positions. The top was a momentary position (spring loaded), the center was off, and the bottom was run. So to start the motor, you push up on the toggle and hold until the motor gets running (one to two seconds), then pull the toggle down into the run position.
That way, you couldn't run the motor with the starting cap in the circuit (unless you stand there and hold the switch up). But if you went from "off" to "run" (the bottom switch position) the motor would not start.
I wired my friend's motor according to the directions that came with it. There may be different directions on this motor and the motor may not be exactly the same - but I think it is the same. It may be possible to run this motor with the starting cap in the circuit but the directions I had specifically called for the starting cap to be removed after start. If you can leave the starting cap in the circuit, all you'd need is a simple on/off switch to operate the motor.
Mike
This pump was designed for industrial control. The motor is a single phase induction motor but it does not have the internal centrifugal switch that a regular single phase induction motor would have to switch the starting capacitor in and out of the circuit. So what you have to do is rig up some switching arrangement that puts the starting capacitor in the circuit when you're starting up the motor but disconnects it after the motor starts. (the notes that came with the motor indicated a timed switch which would remove the starting cap a certain number of seconds after power was applied)
What I did was use a DPDT toggle switch with three positions. The top was a momentary position (spring loaded), the center was off, and the bottom was run. So to start the motor, you push up on the toggle and hold until the motor gets running (one to two seconds), then pull the toggle down into the run position.
That way, you couldn't run the motor with the starting cap in the circuit (unless you stand there and hold the switch up). But if you went from "off" to "run" (the bottom switch position) the motor would not start.
I wired my friend's motor according to the directions that came with it. There may be different directions on this motor and the motor may not be exactly the same - but I think it is the same. It may be possible to run this motor with the starting cap in the circuit but the directions I had specifically called for the starting cap to be removed after start. If you can leave the starting cap in the circuit, all you'd need is a simple on/off switch to operate the motor.
Mike