Question
Asked 14th Nov, 2015

Is it possible to control AC motor speed using ceiling fan regulator?

The specification for AC motor is:
Single phase, 230 Volt, 0.37kW and 0.5Hp.
Attacted is picture wire connection from regulator to AC motor.

Most recent answer

18th Nov, 2015
M. Arun Noyal Doss
SRM Institute of Science and Technology
Yes it is possible but depends on the ratings of the machine 

All Answers (14)

14th Nov, 2015
Bhupendra Desai
Indian Institute of Technology Roorkee
Yes it is possible, if rating(KW/HP) of single phase motor are equal or less.
1 Recommendation
15th Nov, 2015
Christian E. Jacob
Max Planck Institute for Plasma Physics
Dear Nur Syafiqah, it is not reasonable. The Speed characteristic of ceiling fan is non-linear. The AC motor has many more losses in lower speed and will be thermal overloaded.  
1 Recommendation
15th Nov, 2015
Sudha Balagopalan
Vidya Academy of Science & Technology
It may be good to have a circuit diagram of the ac  motor to see what is the equivalent of a capacitor to split the phase. Logically there should not be any difficulty for speed control with a thyristor based regulator so long as the voltage does not go below a particular level.
1 Recommendation
15th Nov, 2015
Nur Syafiqah Hashim
Universiti Malaysia Pahang
if i proceed to test it, it will cause my motor?
15th Nov, 2015
Sudha Balagopalan
Vidya Academy of Science & Technology
I don't think anything will go wrong. However, why not use an autotransformer to slowly increase the voltage if you are concerned. I have experimented with many things, so long as theory is supportive.
1 Recommendation
15th Nov, 2015
Nur Syafiqah Hashim
Universiti Malaysia Pahang
i will try my best. thank you for your idea.
17th Nov, 2015
Subbanna Chittiboena
National Institute of Technology Tiruchirappalli
Madam Nur Syafiqah Hashim,
Generally the ceiling fan regulator is rated for 60-80 Watts. But your AC machine rating is 370 Watts. If you connect fan regulator to your AC machine, regulator can not handle this much power and it will burn. Be careful in doing this experiment.
All the best. 
17th Nov, 2015
Nur Syafiqah Hashim
Universiti Malaysia Pahang
i think the power for ceiling fan is less than motor. so it will be find right?
17th Nov, 2015
Alexander Pugachev
Bryansk State Technical University
Hello,  Nur Syafiqah!
If you want to apply ceiling fan regulator for control of single phase AC motor then you have to check their current not power. But if they both designed for ~230V then the ratio of its power roughly reflects the ratio of its current. It means that if the power of ceiling fan is less than the power of AC motor then you don't have to adjust regulator for voltages closed to 230V because the AC stator current will exceed the rated current of regulator. Generally, the less voltage on the stator winding of AC, the less current (it concerns, first of all, the no-load mode (it is not clear if your AC motor has any load) because the value of AC motor current under load depends mostly on value of the load torque). But, indeed, efficiency of motor sharply reduces under non-rated values of voltage. It means that a considerable decreasing of voltage causes a less decreasing of current. To sum up, I would say that you can control the motor by your regulator but only in the range of voltages that much less than 230V.
To overcome any confusions and doubts (because there are a number different opinions), you can apply AC ampere-meter. Firstly, connect it series to your fan and find out how much current is. Then, connect the ampere-meter series to AC motor lined to grid (I mean connect AC motor with ampere-meter to the grid without any regulator) and learn how much current is in this case. As you understand, if the motor current is less than the fan one then you can apply regulator for control of AC motor. If it is not, you can try, nevertheless, to control your motor by regulator checking the Amperes simultaneously. I guess that regulator has enough reserve to control the motor under low values of voltages.
Best wishes to you and all participants!   
1 Recommendation
17th Nov, 2015
Nur Syafiqah Hashim
Universiti Malaysia Pahang
thank you Alexander. but i already try to connect it. but only in speed 5 the motor move. the other speed not move. can i know why this happend?
17th Nov, 2015
Sudha Balagopalan
Vidya Academy of Science & Technology
Is the fan regulator a thyristor controlled one or the old resistance/ inductor one?
17th Nov, 2015
Alexander Pugachev
Bryansk State Technical University
Is the position of "5" highest in a range of regulator? It can be so that the low positions of your regulator don't provide the voltage that need to start. The torque of motor depends on square of voltage, it means that if you reduce the voltage two times (from 203 to 115V) then the maximum torque will reduce four times at once! If there were any load or some obstacle for free moving, it could be enough to slow or stop the shaft of motor.
17th Nov, 2015
Nikhil Krishna Bajjuri
Hind Rectifiers Pvt. Ltd.
The picture attached with the query gives me an impression that its a old resistive control which is obviously for a load with a rating in the range of 100W to 180W.(Fan regulators are designed generally for 140W and 160W fans). So if you want to operate a 0.5hp motor then I don't think it would withstand the load. But if it withstands, then u can have 4th and 5th speed range only.

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