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Maybe someone can help me: We measured the impulse voltage on high voltage coils. The result was, that the impulse voltage level is higher if the test is made in some steps. E.g. one coil withstands about 50kV, if the test started with an impulse voltage of 30kV, then with 32kV, 34kV, .... If we...

Ask the motor supplier, maybe they can help you. A rewind of the motor from 4 to 8 pole is probably possible, if the number of slots is enough (48, 72, ...). The cooling is not so good because of the low speed if the van remains. So you have to decrease the rating. And you will get a low power...

If you keep the rating constant, the motor will run with an decreased moment (temperature rise will decrease - about 10% lower losses). If you keep the torque constant, the losses will increase about 5 to 10%. The rating will increase about 20%.

A solution could be an internally cooled motor with intake/outgoing flange. Maybe Loher (Germany) (www.loher.de) can help you.

To kiribandas comment: If the motor was running with reduced power - you have not a cold situation!!!! E.g. the motor was runnning with 90% rating means that the temperature rise of the motor is appr. 80% of the maximum rise. Cold condition means that the maximum motor temperature before the...

PAP, yes you can have 3 succesive starts without any period between the starts. After the last start you have to wait before you start the motor again. Typicall number of starts: 3/2 (cold/hot) This means, if the motor is cold you can make 3 starts, if the motor is hot (motor was running with...

I agree with jraef, if you do not have an sealed motor with absolute dry air inside, water will always condensate if the motor stoppr running and if the housing is cooled from outside. You can avoid this problem by drying the winding up before closing the motor (in every insulation material you...

If you design a large motor for a lower rating the power factor will increase (lower induction). But the efficiency will probably decrease (higher friction losses for a larger motor, ...) so the effect will be negative.

Ask the motor manufacturer for the max. thrust which is allowed for these motors. You will get an answer. Compare it with the real thrusts.

Hi Lucino, e.g. if you want to compensate from a powerfactor of 0,9 to 0,95 and you have an electric motor with a mechanical rating of 400kW with an efficiency of 95%, you need QC = 400/0,95 x (tan(invcos(0,90)) - tan(invcos(0,95)) = 65kvar

Qc = Pel x (powerfactor[old] - powerfactor[new])