Electrical Machine - I (3140913) MCQs

MCQs of DC Machines

Showing 151 to 160 out of 167 Questions
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151.
In a Dc generator, the magnetic neutral axis coincides with geometrical neutral axis, when
(a) the generator runs on designed speed
(b) there is no load on the generator
(c) the generator runs on overload
(d) the generator runs on full load
Answer:

Option (b)

152.
A 220 V separately excited DC generator is run at full speed without any excitation. The open-circuit voltage will be
(a) zero
(b) about 2 V
(c) about 50 V
(d) 220 V
Answer:

Option (b)

153.
If residual magnetism is present in a DC generator, the induced emf at zero speed will be
(a) small
(b) high
(c) zero
(d) the same as rated voltage
Answer:

Option (c)

154.
With the increases in field excitation of a DC generator, its generated emf
(a) decreases
(b) increases
(c) remains constant
(d) increases up to a limit and then remains almost constant
Answer:

Option (d)

155.
The slight curvature at the lower end of the OCC of a self-excited DC generator is due to
(a) high speed
(b) residual flux
(c) magnetic inertia
(d) high field resistance
Answer:

Option (b)

156.
A generator may lose residual magnetism due to
(a) vibrations
(b) heating
(c) overexcitation
(d) any of these
Answer:

Option (b)

157.
Which of the following DC generators has rising V-I characteristics?
(a) Shunt
(b) Series
(c) Compound
(d) None of the above
Answer:

Option (b)

158.
For a specific open-circuit voltage of a DC generator, the short-circuit electric current will be maximum when it is
(a) shunt connected
(b) differentially compounded
(c) cumulatively compounded
(d) separately excited
Answer:

Option (c)

159.
The voltage regulation of a DC generator at full load being zero implies that the generator is
(a) series connected
(b) shunt connected
(c) deferentially compounded
(d) cumulatively compounded
Answer:

Option (d)

160.
The ___________________ generator has the poorest voltage regulation.
(a) under-compounded
(b) differential compounded
(c) shunt
(d) over compounded
Answer:

Option (b)

Showing 151 to 160 out of 167 Questions
12 13 14 15 16 17