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GATE EE 2022
Numerical
+2
-0

A 3-phase, 415 V, 50 Hz induction motor draws 5 times the rated current at rated voltage at starting. It is required to bring down the starting current from the supply to 2 times of the rated current using a 3-phase autotransformer. If the magnetizing impedance of the induction motor and no load current of the autotransformer is neglected, then the transformation ratio of the autotransformer is given by ________. (round off to two decimal places).

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2
GATE EE 2018
Numerical
+2
-0
The equivalent circuit of a single phase induction motor is shown in the figure, where the parameters are

R1 = R2' = Xl1 = Xl2' = 12 $$\Omega $$, Xm = 240 $$\Omega $$

and s is the slip. At no-load, the motor speed can be approximated to be the synchronous speed. The no-load lagging power factor of the motor is___________ (up to 3 decimal places). GATE EE 2018 Electrical Machines - Induction Machines Question 11 English
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3
GATE EE 2017 Set 2
Numerical
+2
-0
A star-connected, 12.5 kW, 208 V (line), 3-phase, 60 Hz squirrel cage induction motor has following equivalent circuit parameters per phase referred to the stator. R1 = 0.3 Ω, R2 = 0.3 Ω, X1 = 0.41 Ω, X2 = 0.41 Ω. Neglect shunt branch in the equivalent circuit. The starting current (in Ampere) for this motor when connected to an 80 V (line), 20 Hz, 3- phase AC source is __________.
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4
GATE EE 2017 Set 1
Numerical
+2
-0
A 375W, 230 V, 50 Hz capacitor start single-phase induction motor has the following constants for the main and auxiliary windings (at starting): $$Z_m=\left(12.50\;+\;j15.75\right)\;\Omega$$ (main winding), $$Z_a=\left(24.50\;+\;j12.75\right)\;\Omega$$(auxiliary winding). Neglecting the magnetizing branch the value of the capacitance (in µF ) to be added in series with the auxiliary winding to obtain maximum torque at starting is _______.
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