Originally Posted by bilinghm  The leeson catalog says it is reccommended that 2 pole motors should be limited to 75 hertz unless they have special preparation. That would be a 25% increase, so about 4,500 RPM? I understand that some 1,800 RPM motors can handle 120 hertz (100% increase) but that is still only 3,600 RPM. Maybe they are in danger of will throwing a winding.
Bill |
4 pole motors can handle over 120 Hz if the winding is capable, the problem is that the frequecy exceeds the ablity of the motor to translate the torque(properly stated the rotor currents are too chaotic), hence it stalls almost instantly at that point, I installed a 4 pole TENV motor in a conveyor a year ago and it could only handle 93 Hz after that it just stopped and sat there, tried a smiiliar motor and it ran to 110Hz, but it lacked the mounting I needed so I was stuck with 93 Hz topend.
The winding is actual called a stator, its stationary on the frame, the rotor, is on the shaft and is laminated steel pushed together and welded, I have never heard nor seen a small motors rotor coming apart, it would take alot of force I would say the endbells would be destroyed long before that would happen, the biggest concern in reagrds to the rotor is that it becomes to hot and warps and starts to touch the stators own lams, in which case you get a rub, I have seen that happen, alot, typically a overheat condition but also overvoltage has caused it, generally the motor is junk at that point.
chris