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00000EE205121905

Derive the electro dynamic equation of rotating electrical machine and explain
the principle of energy conversion?
PART (^
Answer any two full questions, each carries 10 marks.
With a neat diagram explain the speed control of a DC shunt motor.
An ideal 25 kVA transformer has 500 turns on the primary winding and 40 turns
in the secondary winding. The primary is connected to 3000V, 50112 supply.
Calculate (i) primary and secondary current on full load (ii) secondary e.m.f
(iii) the maximum core flux.
Draw the phasor diagram of a single phase transformer supplying inductive load
Explain briefly the different cooling methods employed in transformer
A 100 kW, 460V shunt generator was run as a motor on no load at its rated
voltage and speed. The total current taken was 9.8A including a shunt current of
2.7A. The resistance of the armature circuit at normal working temperature was
0.11Q. Calculate the efficiency of the generator at (i) full load (ii) half load.
PART D
Answer any two full questions, each carries 10 marks.
Explain the operation of an autotransformer. How saving of copper is achieved in
an autotransformer as compared to an ordinary two winding transformer?
With a neat circuit diagram, explain how a two-phase supply can be obtained
from a three-phase supply.
A 10 kVA, 200/400V, 50Hz single phase transformer gave the following result.
O.C test: 200۷, 1.34. 120४0 ................ on L.V side
S.C test: 22۷, 30A, 2009 ................ on H.V side
Calculate (i) the magnetising current and the component corresponding to core
loss at normal frequency (ii) the magnetising branch impedances.
In 1998, there was ೩ 10011۷۸ transformer serving power to a locality. Due to
sudden industrial revolution, there was a need to parallel another 1001൧
transformer. Suggest various conditions to be satisfied to successfully parallel the

two three-phase transformers.

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