12

13

14

15

16

17

b)

a)

b)

C1139 Pages 2

terminal voltage of 230 V. Determine the efficiency of the generator at full load,
assuming the iron, friction and windage losses amount to 500 W.

Write any three differences between wave winding and lap winding.

PART C
Answer any twofull questions, each carries10 marks.

What is the necessity of a starter for motor? With a suitable diagram, explain the
working of 3 point starter.

With suitable diagram, how the Swinburne’s test can be employed to
predetermine the efficiency at full load condition when running as a generator
Differentiate between core type and shell type transformers.

Explain the working of a transformer on no-load and load condition.

PART D

Answer any twofull questions, each carries 10 marks.
Derive the condition for maximum efficiency of transformer. How the efficiency
of a transformer depends on load?
Why the star delta three phase transformer is used to step down the voltage in
transmission system
A 600W single phase transformer working at unity power factor has an
efficiency of 95 percent at both half full load and full load. Determine the
efficiency at 70 percent of full load.
With neat circuit diagram, explain how a two phase supply can be obtained from
a three phase supply. Prove that three phase currents will be balanced, for a

balanced upf load on 2-phase side.

Page 2 of 2

(3)

(10)

(6)

(4)
(10)

(5)

(5)

(10)

(10)