T
Tom Peel
Hi
We have a kitchen extractor fan which had the speed control burn out- it
was a pretty crude affair using a huge resistor around 200 Ohm with
sections shunted out with a switch, and this in series with the motor. I
threw it out and bought a solid state speed control unit, the kind with
an external potentiometer to control the motor speed. It works great at
low inputs, however if you try to wind the speed up, the motor starts
"chugging", that is, it speeds up for about 2 seconds, then the speed
dies and drops back, repeating over and over. I guess it must be back
emf from the motor that is causing the current to drop, but it's just a
guess. I have no information about the motor, I guess it's a brushless
induction motor. The speed control is some kind of sealed unit with a
thyristor circuit.
Any idea how I can stop the motor surge and get more output? It seems
odd to me, even if it is back emf, that the speed never stabilises.
T.
We have a kitchen extractor fan which had the speed control burn out- it
was a pretty crude affair using a huge resistor around 200 Ohm with
sections shunted out with a switch, and this in series with the motor. I
threw it out and bought a solid state speed control unit, the kind with
an external potentiometer to control the motor speed. It works great at
low inputs, however if you try to wind the speed up, the motor starts
"chugging", that is, it speeds up for about 2 seconds, then the speed
dies and drops back, repeating over and over. I guess it must be back
emf from the motor that is causing the current to drop, but it's just a
guess. I have no information about the motor, I guess it's a brushless
induction motor. The speed control is some kind of sealed unit with a
thyristor circuit.
Any idea how I can stop the motor surge and get more output? It seems
odd to me, even if it is back emf, that the speed never stabilises.
T.