Running a 50 Hz motor with 100 Hz 2

[Zahid.Abu]

I want to run a 50 Hz motor with 100 Hz. The reason is to increase rpm for increasing powder product dosing. Torque is not important here. The motor insulation class is Th.Cl. 155 (F). Is there any chance of damaging the winding during running at 100 Hz?

 

[waross]

It depends a lot on the type of motor.
What are the motor specs?
How is the motor driven now?
If the motor will be inverter driven, how long are the leads from the inverter to the motor?
How do you intend to source the 100 Hz supply?
Is the motor inverter rated?
Will you use a sine wave filter?
If this is a standard, inverter rated, three phase induction motor it is probably safe to run it at 100 Hz.
The danger to the motor is more from the unfiltered inverter wave form than from the higher frequency.
It depends but at a higher frequency the torque may be increased by increasing the applied voltage or by connecting the motor for a lower voltage.
eg: Feed 400 Volts at 100 Hz to a motor connected for 230 Volts, or double the voltage with a transformer.
A 230 Volt motor at 50 Hz has a Volts per Hertz ration of 4.6 Volts per Hz.
At 100 Hz and a V/Hz ratio of 4.6 V/Hz you can increase the voltage to as much as 460 Volts without fear of saturation.
Mechanically there may be unintended issues with bearings, fans or vibration.
Probably not but be warned of the possibility.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[controlsdude]

Its been my experience that mechanical will spec out the motor to run at a rpm that is the rated speed. Usually the mechanics around a motor are 1.3x above rated speed. So anything above 75 hz would be a question for mechanical side to verify if it can handle that speed.

Also be aware that a VFD has a max frequency setting as a parameter, you would have to adjust this to get to the 100hz.

 

[itsmoked]

Also, depending on the driven load, if it is 'fan like' (blowing powder?) you actually will become concerned about the torque, probably at a squared or possibly cubed rate of concern.

Keith Cress
kcress -

http://www.flaminsystems.com