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A pair of similar DC shunt generators operates in parallel and supply a common load. It
is required to switch off machine 1 and allow machine 2 to supply the entire load. The
following operations are to be used to achieve this

i. switch off the main switch of machine 1
1. reduce the field current of machine 1
iii. increase the field current of machine 2
iv. ensure that machine 1 just floats.
The correct sequence of these operations are

A) iv | iii ர்‌ i
B) ii iii iv i
C) ii iv iii i
D) iii ii iv i

The most suitable generator for welding purpose is
A) shunt generator B) separately excited generator
C) cumulative compound generator D) differential compound generator

In DC shunt motors, the field excitation is kept maximum value during starting to
A) increase acceleration time

B)

C) reduce armature heating

D) prevent voltage dip in the supply mains

decrease starting torque

Three point starters of DC shunt motors are not used in applications where speed variation

by field flux control is required because

A) the motor may stop at very high speeds

B) the motor may stop at very low speeds

C) the motor may stop both at very high and at very low speeds
)

D) the motor may run away

For variable heads of near about less than 30 m, which type of turbine is used in
hydropower station ?

A) Pelton turbine B) Kaplan turbine

C) Francis turbine D) None of these