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GATE 2019: Electrical Machines Quiz 9
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Question 1
The starting line current of a 415V. 3-phase, delta connected induction motor is 120A, when the rated voltage is applied to its stator winding. The starting line current at a reduced voltage of 110V, in ampere is ______.
Question 2
While controlling the speed of a 3-phase induction motor by varying the supply frequency, which of the following requirement should be fulfilled?
Question 3
The power input to a 415V, 50 Hz, 6 pole, 3-phase induction motor running at 975 rpm is 40 kW. The stator losses are 1kW and friction and windage losses total 2 kW. The efficiency of the motor is
Question 4
A 3-ϕ, 12 poles, Y connected alternator has 180 slots with 10 conductors per slot and conductors of each phase are connected in series. The coil span is 144 ° (electrical) and flux per pole is 60 m Wb. If the machine runs at 750 rpm, the phase voltage is _________ kV.
Question 5
An iron ring of mean length 50 cm has an air gap of 1 mm and a winding of 200 turns. If the permeability of the iron is 300 when a current of 1 A flows through the coil, find the flux density
in Wb/m2.
in Wb/m2.
Question 6
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: 
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 __________.
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 __________.- 896 attempts
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Dec 14ESE & GATE EE
