AC THREE PHASE MOTOR - Quiz

1) What is the effect of motor, if the rotor windings in slipring induction motor is open circuited at starting?

Will not run Runs at slow speed Runs at very high speed Runs but not able to pull load

2) What happens to a 3 phase induction motor if one phase fails during running?

Motor runs normally Motor stop instantaneously Motor runs slowly, finally it burns Motor runs with irregular speed

3) What is the effect on 3 phase induction motor if one phase is cut-off during running with load?

Motor stops at once Motor will run normally Motor runs with humming noise with slow speed Motor will run slow speed but winding will be burnt out shortly

4) What is the defect, if starter with single phasing preventer does not switch ON?

Improper phase sequence Fluctuations in line voltage Loose contact in supply lines Wrong terminal connections at motor

5) What is the defect in AC 3 phase induction motor runs at low speed if loaded?

Wrong motor connection Wrong starter connection Open circuit in rotor winding Partially shorted stator winding