This question was previously asked in

PTCUL AE E&M 2017 Official Paper (Set B)

- Equal to the supply frequency
- Less than the supply frequency
- More than the supply frequency
- Zero

Option 1 : Equal to the supply frequency

__ Concept__:

**Slip in Induction Motor (s)**

\(s=\frac{N_s\ -\ N_r}{N_s}\) ---(1)

Where,

N_{s} is the stator frequency

N_{r} is the rotor frequency

Also, fr = s fs ---(2)

Where,

fr is the rotor frequency

fs is the supply frequency

__ Explanation__:

The rotor is locked means N_{r} = 0

So, from equation (1), s = 1

From equation (2),

**fr = fs**

Therefore, the rotor frequency of the induction motor = supply frequency.

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