How do you test an induction motor rotor?

What is the slip of induction motor when rotor is blocked?

Generally, the slip of the induction motor varies between 2 to 4 percent, and the resulting rotor frequency is in the range of 1 to 2 hertz for the stator frequency of 50 hertz at the normal conditions. This test should be performed at a reduced frequency.

How is the induction motor blocked rotor test similar to the short circuit test of a transformer?

THEORY: Blocked rotor test is similar to the short circuit test on a transformer. It is performed in the to calculate the series parameters of the induction machine i.e., its leakage impedances.

When a 3 phase induction motor is blocked What is the rotor?

When the motor is blocked i.e., rotor is at zero speed.

How do you test a rotor motor?

HIGH CURRENT ROTOR TEST – This test is performed by applying high current through the shaft of the rotor (rotor out of stator) and thermally scanning (infrared or thermoscan) the rotor O.D. searching for shorted laminations. These shorted laminations cause localized hot spots which cause uneven heating of the rotor.

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What happens if fifth harmonics is given to induction motor?

It will rotates in normal operation. Either short circuit or open circuit occurs. The sinusoidal components having frequency five times of fundamental are known as fifth harmonics. … Hence induction motor will rotates in reverse direction because of reverse phase sequence of fifth harmonics.

Why is locked rotor current important?

The locked rotor current (information) is used to choose the overcurrent protection device (circuit breaker / fuse). An electrician has to install the correct breaker, or fuse, to prevent tripping on motor startup, as well as to protect the motor. Knowing the locked rotor current is certainly not useless.

Why LPF wattmeter is used in no load test of induction motor?

Answer: LPF wattmeter is used to measure power in inductive circuits. … In open circuit test the secondary winding of transformer is kept open.As the secondary side is open, the entire coil will be purely inductive in nature.So the power will be lagging due to inductive property of the circuit.

Why blocked rotor test is performed at reduced frequency?

If, however, one is interested in normal running characteristics, the blocked-rotor test should be taken at a reduced voltage which results in approximately rated current; the frequency also should be reduced, since the values of rotor effective resistance and leakage inductance at the low rotor frequencies …