A three phase squirrel cage induction motor has the nameplate data shown in Table I below
Table I : Induction Motor Nameplate Data.
a) Calculate the induction motor efficiency for the load test.
b) It is required to supply the same torque at a speed of 1200rpm. Approximately, determine the supply voltage and frequency required to achieve this speed and torque condition.
[Hint: Neglect the effects on the induction motor variable speed torque response due to R1 and the mechanical losses.]
c) Explain why the supply frequency must change from 50Hz in order to achieve the loading condition.