# Variable Speed Drive For Single Phase Capacitor Start/run Motor

Single Phase Motor Inverter VFD Capacitor Start/Run Motor Reversing Motor Rotation

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### #1 Zaaf

Zaaf

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Posted 25 December 2013 - 02:43 PM

I am building a VFD for single phase Capacitor Start/Run Motor. There are two windings the main and start/run winding. Main winding having low resistance means high power and start/run winding has twice the resistance of main winding means low power. I have read everywhere that for reversing the direction of motor we have to switch the leads. My one question is that if I connect capacitor to the main winding instead of start/run winding will the motor get burn? As a matter of fact I have done this thing on pedestal fan motor and it runs fine and I can change the direction of the motor this way. I have asked about this thing from a motor winder and he said that this way motor can get burn. My second question is that if the motor will get burn what could be the reason because I think the load will always be on the main winding and until unless this way if both windings in this configuration are not able to produce the required magnetic field then there is possible chance that it will get burn.

I have read that capacitor creates around 80° to 90° leading phase shift of current in the start/run winding which creates the rotating magnetic field and motor runs in forward direction. If we change the leads for the start/run winding the current will lag 80° to 90° in the start/run winding and motor will run in reverse direction (am I correct here because I have little doubt). According to my thinking same should happen when I will connect the capacitor to the main winding instead of start/run winding and motor will run in reverse.

Now, I come to my third and final question for which I have almost written an essay above that if I build a two phase inverter with 90° phase shift between them will I be able to run the motor? My main concern was that will I burn the start/winding with this technique or should I change voltage level in the second phase which will I give to the star/run winding so that the current is limited in this winding?

Regards.

### Also tagged with one or more of these keywords: Single Phase Motor, Inverter, VFD, Capacitor Start/Run Motor, Reversing Motor Rotation

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