A three-phase motor is used to drive a pump. It is observed (by the use of a stroboscope) that the motor speed decreases from 898r/min when the pump is unloaded to 830 r/min as the pump is loaded.
a. Is this a synchronous or an induction motor?
b. Estimate the frequency of the applied armature voltage in hertz.
c. How many poles does this motor have?