Q7Basic Electrical Engineering

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Q.7 Define slip in induction motor.

Answer 1

In three-phase induction motors, the physical rotor fundamentally cannot ever rotate at the exact identical synchronous speed ( $N_{s}$ ) of the stator's rotating magnetic field. If it did, absolutely no relative magnetic flux would be cut, resulting in zero induced torque.

Slip ( $s$ ) is the critical mathematical parameter that explicitly quantifies this speed difference. It is rigorously defined as the ratio of the slip speed strictly to the synchronous speed:

s = \frac{N _{s} - N _{r}}{N _{s}}

where $N_{s}$ is the synchronous speed and $N_{r}$ is the actual rotor speed. For standard motors, normal full-load slip values strictly range from approximately 2% to 5%.

Q7Basic Electrical Engineering

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