Question:
A three-phase, 50 Hz, 6-pole induction motor runs at 960 rpm. The stator copper loss, core loss, and the rotational loss of the motor can be neglected. The percentage efficiency of the motor is:
A three-phase, 50 Hz, 6-pole induction motor runs at 960 rpm. The stator copper loss, core loss, and the rotational loss of the motor can be neglected. The percentage efficiency of the motor is:
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Efficiency of induction motors can be approximated using \( \eta = 1 - \text{slip} \) when losses are negligible.
Updated On: Sep 14, 2025
- \( 92 \)
- \( 94 \)
- \( 96 \)
- \( 98 \)
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The Correct Option is C
Solution and Explanation
Step 1: Calculating synchronous speed.
The synchronous speed is:
\[
N_s = \frac{120 f}{P} = \frac{120 \times 50}{6} = 1000 \, \text{rpm}.
\]
Step 2: Calculating slip.
\[
\text{Slip} (s) = \frac{N_s - N_r}{N_s} = \frac{1000 - 960}{1000} = 0.04.
\]
Step 3: Calculating efficiency.
Efficiency (\( \eta \)) is given by:
\[
\eta = 1 - s = 1 - 0.04 = 0.96 \, \text{or } 96\%.
\]
Hence, the correct option is (3) \( 96 \).
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