08-05-2014, 04:26 PM
Hi,
That is a very small motor Dave. It depends on the motor regarding the three coils. If the motor has six leads from the coils then it can be connected in either Star or Delta. I'm unfamiliar with such a small 3 phase motor but on bigger motors depending on age many old 3 phase motors had their Star connection buried deep in the windings and trying to dig out this connection could well render the motor beyond use. Star generally is 415V.
However if the six leads are accessible then the motor can be connected in Delta which is what I think you require allowing it to run from 240V? I don't know if a VFD (inverter) is available for such a small size and to hook up this small motor using a start and run capacitor would reduce its output even further? The short answer is yes if it has six leads but I wouldn't recommend it.
Good question regarding the capacitors though and not an easy one to answer. The run capacitor needs to be chosen in value so that under power the third phase (supplied by the capacitors) is balanced as much as possible by taking amps readings. The start capacitor isn't critical because it is in circuit only long enough to bring the motor up to speed. You will also need means to drop the start cap off-line once the motor is up to speed; this can be done using a relay or for simplicity I use two start buttons pressing both to start the motor and hold in until the motor is up to speed then when I release both buttons the run capacitor remains connected but the start capacitor drops off-line; not easy for a novice.
I installed 3 phase 415V into our garage a few years ago winding my own transformer and this was most interesting if somewhat highly dangerous for a novice like me. I was fascinated as I balanced the third phase to the motor using capacitors; putting capacitors in and taking capacitors out changed the voltage and I was able to obtain exactly 415V with trial and error but on such a small motor as yours is it worth the time and effort unless of course it's intended for a special application?
Does your motor have a nameplate attached Dave?
As Joe kindly adds this question is covered in the link supplied but on a much larger motor.
Kind regards, Col.
That is a very small motor Dave. It depends on the motor regarding the three coils. If the motor has six leads from the coils then it can be connected in either Star or Delta. I'm unfamiliar with such a small 3 phase motor but on bigger motors depending on age many old 3 phase motors had their Star connection buried deep in the windings and trying to dig out this connection could well render the motor beyond use. Star generally is 415V.
However if the six leads are accessible then the motor can be connected in Delta which is what I think you require allowing it to run from 240V? I don't know if a VFD (inverter) is available for such a small size and to hook up this small motor using a start and run capacitor would reduce its output even further? The short answer is yes if it has six leads but I wouldn't recommend it.
Good question regarding the capacitors though and not an easy one to answer. The run capacitor needs to be chosen in value so that under power the third phase (supplied by the capacitors) is balanced as much as possible by taking amps readings. The start capacitor isn't critical because it is in circuit only long enough to bring the motor up to speed. You will also need means to drop the start cap off-line once the motor is up to speed; this can be done using a relay or for simplicity I use two start buttons pressing both to start the motor and hold in until the motor is up to speed then when I release both buttons the run capacitor remains connected but the start capacitor drops off-line; not easy for a novice.
I installed 3 phase 415V into our garage a few years ago winding my own transformer and this was most interesting if somewhat highly dangerous for a novice like me. I was fascinated as I balanced the third phase to the motor using capacitors; putting capacitors in and taking capacitors out changed the voltage and I was able to obtain exactly 415V with trial and error but on such a small motor as yours is it worth the time and effort unless of course it's intended for a special application?
Does your motor have a nameplate attached Dave?
As Joe kindly adds this question is covered in the link supplied but on a much larger motor.
Kind regards, Col.
Happiness is a wreck of a cabinet to restore.
