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GATE EE 2021: Electrical Machine Rapid Quiz 3 (App update required to attempt this test)

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Question 1

The high frequency hum in the transformers is mainly due to

Question 2

For a 3-phase induction motor, the torque-slip characteristic for a low slip region can be expressed as:

Question 3

A single 50Hz, synchronous generator on droop control was delivering 100 MW power to a system. Due to increase in load, generator power has to be increased by 10 MW, as a result of which, system frequency dropped to 49.75 Hz. Further increase in load in the system resulted in a frequency of 49.25 Hz. At this condition, the power in MW supplied by the generator is_______. (rounded off to 2 decimal places).

Question 4

A 240V DC shunt motor having armature and field resistances of 0.5 Ω and 60Ω respectively. The stray losses are 500 W in the machine. Calculate the efficiency of motor when machine is taking current of 44 A from supply mains.

Question 5

A 3-phase Y-connected synchronous generator is rated as 150 MVA, 13 kV lagging and 50 Hz. It has a synchronous reactance of 0.6 Ω and the resistance is negligible. If it is operated at 60 Hz with the same armature and field losses as it has at 50 Hz, then rated voltage and apparent power rating of the generator are respectively.

Question 6

A 5 hp, 4-pole, 50 Hz, 3-ϕ induction motor is operating at 1440 rpm on full load. The stator copper loss 100 W and rotational loss is 250 W. Find the efficiency of motor? (Take 1 hp = 746 W)
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Posted by:

Shivang AgrawalShivang AgrawalMember since Jan 2020
M.tech(NIT Nagpur) GATE Ranker[2015-18]
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