I'm working with a 1/12 HP Single Phase 60 Hz 120V PSC motor with a 10 mfd CAP permanently installed across the start winding.
At full power it works great. However, I am interested in adding a speed control.
I built the this SIMPLE TRIAC MOTOR SPEED CONTROL :
It works Wired in series with the AC +in line. But it does not give repeatable high resolution control.
If the VR1 is over about 70Kohm the motor is off. As I drop the resistance the current flows.
Initially the motor goes through a slow start...similar in style to the quick ramp up that a PSC motor does with full power...only now lasting much longer because the speed controller is delivering only part of the power to the system. There is also a very small range of resistance values right around 70Kohm where this low power humming rotation can be sustained indefinitely.
A few clicks below 70 kohm the motor actually hits a smooth high speed rotation. Now I can continue to vary the VR1 and the smooth high speed rotation gets a little faster and a little slower as it should.
The thing that confuses me is this:
I am only able to vary the speed within a few percent of the rated RPM. I estimate that I when I get past the slow start (mentioned above) and get it initially running fast and smooth, that it's running at about 85% of rated speed and I can take it up to what seems like 100% rated speed when VR1=0
Drawing the speed down from 100% doesn't act quite the same...on the way down I can actually take VR1 down well below 70k ohm...to about 30kohm or so before the motor stalls.
Any ideas about this system. Is it even plausible to control said motor with said control circuit over a large range? What happens if I replace the 10mfd run cap with a smaller cap?
Is it possible to control any PSC motor over a wide range?
At full power it works great. However, I am interested in adding a speed control.
I built the this SIMPLE TRIAC MOTOR SPEED CONTROL :
It works Wired in series with the AC +in line. But it does not give repeatable high resolution control.
If the VR1 is over about 70Kohm the motor is off. As I drop the resistance the current flows.
Initially the motor goes through a slow start...similar in style to the quick ramp up that a PSC motor does with full power...only now lasting much longer because the speed controller is delivering only part of the power to the system. There is also a very small range of resistance values right around 70Kohm where this low power humming rotation can be sustained indefinitely.
A few clicks below 70 kohm the motor actually hits a smooth high speed rotation. Now I can continue to vary the VR1 and the smooth high speed rotation gets a little faster and a little slower as it should.
The thing that confuses me is this:
I am only able to vary the speed within a few percent of the rated RPM. I estimate that I when I get past the slow start (mentioned above) and get it initially running fast and smooth, that it's running at about 85% of rated speed and I can take it up to what seems like 100% rated speed when VR1=0
Drawing the speed down from 100% doesn't act quite the same...on the way down I can actually take VR1 down well below 70k ohm...to about 30kohm or so before the motor stalls.
Any ideas about this system. Is it even plausible to control said motor with said control circuit over a large range? What happens if I replace the 10mfd run cap with a smaller cap?
Is it possible to control any PSC motor over a wide range?