Two motors , HP 2 but one is of 2700 rpm and another is 3500 rpm, what is the difference in their structures?

Question

Two motors , HP 2 but one is of 2700 rpm and another is 3500 rpm, what is the difference in their structures?

Answer 1

Assuming they are 2-pole a/c induction motors, the difference is almost certainly the design frequency. A USA motor running on 60 Hz frequency will have an unloaded speed of 3600 rpm reducing to 3500 rpm at the design load and a European motor running on 50 Hz has an unloaded speed of 3000 rpm reducing to 2700 rpm on load. Their is no difference in their structures.

If they are not induction motors the speed rating could be any number of reasons.

Answer 2

*Maximum number of starts .

http://machinedesign.com/ContentItem/611...

*RPM

=120*frequency/no. of poles

Frequency is constant.

So, there will be a change in pair of poles.

http://www.epi-eng.com/piston_engine_tec...

*When the motor is having lower rpm and load is at peak i.e. torque is high , then the motor should be sturdy.