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GATE 2019: Electrical Machines Quiz 2
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Question 1
The internal and external characteristics of a separately excited dc generator is shown below.
Analysing the characteristics, determine the figure that depicts the armature voltage drop.
Analysing the characteristics, determine the figure that depicts the armature voltage drop.
Question 2
The parallel paths of a 4-pole dc machine armature with lap winding, are symmetrical, and each has a resistance of 0.6 Ω. Determine the armature resistance.
Question 3
An emf of 236.8 V is induced in a dc generator, with armature resistance 0.25 Ω. When the generator enters the motoring mode, a back emf of 223.2 V is induced at the same terminal voltage and the same armature current. Determine the value of the armature current.
Question 4
A 230V, 15 kW ,1000rpm shunt motor with armature resistance of 0.50 Ω, has a rated line current of 72 A and a rated field current of 2.2 A. The change in field flux (in %) required to obtain a speed of 1800 rpm while drawing a line current of 54.6 A and a field current of 1.8 A is
Question 5
A DC machine running at 800 rpm induced voltage is 220V. What will be percentage increase in field flux if the induced emf is 240V at 600 rpm?
Question 6
A 25 kVA, 1- φ transformer, 2200 V to 220 V has a primary resistance of 1 Ω and a secondary resistance of 0.01 Ω. Find the full-load efficiency in Percentage, at 0.8 p.f. if the iron loss of the transformer is 80% of the full-load copper loss.
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Jun 21ESE & GATE EE