The locked rotor current in a 3-phase, star connected 15kW, 4-pole, 230V, 50Hz induction motor at rated conditions is 50A. Neglecting losses and magnetizing current, the approximate blocked rotor line current drawn when the motor is connected to a 236V, 57Hz supply is

A 3 phase, 10 kW, 400 V, 4 pole, 50 Hz, star connected induction motor draws 20A on full load. It’s no load and blocked rotor test data are given below:

No Load test  : 400 V  6A 1002 W

Blocked Rotor test : 90 V  15A 762 W

Neglecting copper loss in no Load test and core loss in Blocked Rotor test, estimate motor’s full load efficiency

No-load test on a 3-phase induction motor was conducted at different supply voltages and a plot of input power versus voltage was drawn. This curve was extrapolated to intersect the y-axis. This intersection point yields

A 3 kW, 400V/200V, Delta/Star, 50Hz, three phase, 6-pole induction motor is found to draw a line current of 25A at a power factor of 0.4, when a blocked rotor test is conducted at the rated voltage. The stator and rotor winding resistances in ohms per phase are A and B, if the torque developed by the motor under the above conditions is 25 N-m. Find A+B=

Match the column         

                Test        Machine

(A)        No load and         (P) Transformer

                blocked rotor test

(B) Sumpner’s test         (Q) Induction machine

(C) Swinburne’s test         (R) Synchronous machine

                        (S) DC machine