Electrical Terms

Cogging in Induction Motor

The phenomenon of Magnetic Locking between the stator and the rotor teeth is called Cogging or Teeth Locking. Even after applying full voltage to the stator winding, the rotor of a 3 phase induction motor fails to start. This condition arises when the number of stator and rotor slots are either equal or have an …

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Deep Bar Rotor

The Deep Bar Rotor in an induction motor is used to obtain high rotor resistance at starting and low rotor resistance at the running condition. The figure below shows a deep bar cage rotor with deep and narrow bars.   A bar may be assumed to be made up of a number of narrow layers …

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No Load Test of an Induction Motor

No Load Test is an indirect method used for determining the efficiency and also to determine the circuit parameters of the equivalent circuit of the three-phase induction motors. The open circuit test performed on the transformer. No load test is same as the open circuit test performed on the transformer. In this method the motor …

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Starting of an Induction Motor

A three phase Induction Motor is Self Starting. When the supply is connected to the stator of a three-phase induction motor, a rotating magnetic field is produced, and the rotor starts rotating and the induction motor starts. At the time of starting, the motor slip is unity, and the starting current is very large. The …

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Auto transformer Starter

An Auto transformer Starter is suitable for both star and delta connected motors. In this method, the starting current is limited by using a three-phase auto transformer to reduce the initial stator applied voltage. The figure below shows the motor with the Auto transformer starter. It is provided with a number of tappings. The starter …

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Star Delta Starter

The Star Delta Starter is a very common type of starter and is used extensively as compared to the other type of starting methods of the induction motor. A star delta is used for a cage motor designed to run normally on the delta connected stator winding. The connection of a three-phase induction motor with …

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