What is the purpose of a blocked rotor test?
This test is performed to determine the short circuit current with normal voltage applied to stator; power factor on short circuit; total equivalent of resistance and Reactance referred to stator.
What is the purpose of no load and blocked rotor tests on induction motors?
Aim of the Experiment:
To obtain the variation of no load power and current and blocked rotor power and current with changes in the applied voltage to the stator. 2. To determine the equivalent circuit parameters of an induction motor.
What is Type test of induction motor?
The no load test on an induction motor is conducted to measure the rotational losses of the motor and to determine some of its equivalent circuit parameters. In this test, a rated, balanced ac voltage at a rated frequency is applied to the stator while it is running at no load.
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.
What is rotor power factor?
The rotor power factor is found using θ = tan-1(X2/R2/s) = tan-1(1.066/7.7) = 7.88° and PF = cos(7.88°) = 0.991 and is stated to be lagging.
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 an induction motor rotor?
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.
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.
What are types of induction motor?
There are three basic types of small induction motors: split-phase single-phase, shaded-pole single-phase, and polyphase. In two-pole single-phase motors, the torque goes to zero at 100% slip (zero speed), so these require alterations to the stator such as shaded-poles to provide starting torque.