GATE 2024 IN – Question 62
A three-phase squirrel-cage induction motor has starting torque 100% of full-load torque and maximum torque 300% of full-load torque. Neglect stator impedance. The slip at maximum torque is ______ % (two decimal places).
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Correct answer: 17.00 to 17.30
Explanation
Neglecting stator impedance, $T/T_{max}=2/(s/s_m+s_m/s)$. At starting, $s=1$ and $T_{start}/T_{max}=1/3$, giving $s_m+1/s_m=6$. The physically relevant root below unity is $s_m=3-\sqrt8=0.171573$. Maximum-torque slip is **17.16%**.