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GATE 2019: Electrical Machines Quiz 3 (App update required to attempt this test)

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Question 1

A 4 pole, 50 A, 360 number of conductors wave wounded for a DC shunt generator has field current of 1.5 A. Calculate cross magnetizing and demagnetizing ampere turns per pole at full load if brushes are on Geometric Neutral axis.

Question 2

A 40kW, 240V dc shunt motor taking a current of 18 A when running without external load at 1000 rpm. Armature resistance is 0.5 Ω and field resistance is 80 Ω. Calculate the fixed losses in the machine –

Question 3

In an 8 pole lap wound dc machine commutation technique, we have to reverse the armature current of 5A in 10msec. The inductance of a coil is 1mH, then the value of inductive kick will be

Question 4

A dc series motor with armature resistance of 0.5 Ω, runs at 1000 rpm at 220V taking a current of 10 A. if the speed is reduced to 800 rpm for the same supply voltage and current the extra series resistance (in Ohm) to be inserted would be –

Question 5

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 6

A 4-pole, separately excited, wave wound DC machine with negligible armature resistance is rated for 230 V and 5 kW at a speed of 1200 rpm. If the same armature coils are reconnected to form a lap winding, what is the rated voltage (in volts) and power (in kW) respectively at 1200 rpm of the reconnected machine if the field circuit is left unchanged?
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Jun 21ESE & GATE EE