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Renewable Energy Q&A / Re: Max winding temp
« Last post by Pete on April 19, 2022, 02:45:34 am »Hi LH, I am used to using 50 hz here so a 2 pole motor would have a synchronous speed of 3000 rpm.
In your case it would have a synchronous speed of 3600 rpm. There has to be some slip in an induction motor to produce torque so yep 3585 would be about right.
Most motors I worked on had about 50 rpm slippage. So a 2 pole motor would run about 2950 on 50 hz, a 4 pole motor 1450rpm.
Formula is N ( speed) = 120 x Frequency/Poles.
If you are using a variable frequency drive and slowing the motor down it will not cool as well as it should.
What revolutions is it running at when on 400 volts?
It may be worth adding an external fan to increase cooling if it is running too hot.
The only reason I can think that the motor winder would put thinner wire in is if he did not have the guage he needed on hand.
Big motors like that have many wires in parallel. Usually one measures the guage of each wire, calculates how many circular mils that adds up to and replaces it with the same area of wire. Different guages can be used in parallel as long as the area of the winding is the same.
Some motors ( Siemens) is one example are very tight to rewind. They pack a massive amount of wire into the slots are are a mongrel to rewind.
Pete
In your case it would have a synchronous speed of 3600 rpm. There has to be some slip in an induction motor to produce torque so yep 3585 would be about right.
Most motors I worked on had about 50 rpm slippage. So a 2 pole motor would run about 2950 on 50 hz, a 4 pole motor 1450rpm.
Formula is N ( speed) = 120 x Frequency/Poles.
If you are using a variable frequency drive and slowing the motor down it will not cool as well as it should.
What revolutions is it running at when on 400 volts?
It may be worth adding an external fan to increase cooling if it is running too hot.
The only reason I can think that the motor winder would put thinner wire in is if he did not have the guage he needed on hand.
Big motors like that have many wires in parallel. Usually one measures the guage of each wire, calculates how many circular mils that adds up to and replaces it with the same area of wire. Different guages can be used in parallel as long as the area of the winding is the same.
Some motors ( Siemens) is one example are very tight to rewind. They pack a massive amount of wire into the slots are are a mongrel to rewind.
Pete