Electrical Machine - I (3140913) MCQs

MCQs of DC Machines

Showing 161 to 167 out of 167 Questions
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161.
In a 12 pole triplex lap wound DC armature, each conductor can carry a current of 100 A. The rated current of this armature is
(a) 600 A
(b) 1200 A
(c) 2400 A
(d) 3600 A
Answer:

Option (d)

162.
Resistance commutation is used generally in case of
(a) DC machines above 10 kW
(b) DC machines bellow 5 kW
(c) fractional kW DC machines
(d) none of the above
Answer:

Option (c)

163.
If residual magnetism of a shunt generator is destroyed accidentally it may be restored by connecting its shunt field
(a) to a DC source
(b) to an AC source
(c) to earth
(d) in reverse
Answer:

Option (a)

164.
Armature reaction in dc motor results
(a) decrease in speed
(b) increase in speed
(c) short circuit
(d) open circuit
Answer:

Option (b)

165.
The power flow of a dc motor, with respect to a DC generator is
(a) modified
(b) reversed
(c) increased
(d) none of these
Answer:

Option (b)

166.
A 4 pole dc motor with the armature winding resistance of 0.6 ohms receives a supply of 230 Volt. If the back emf produced during running condition is equal to 210 volts. Calculate the current flowing through the armature at this point.
(a) 43 Amp
(b) 44.47 Amp
(c) 33.33 Amp
(d) 29 Amp
Answer:

Option (c)

167.
The shaft torque of a dc motor is less than the electromagnetic torque because of
(a) mechanical losses
(b) hysteresis losses
(c) ohmic losses
(d) eddy current losses
Answer:

Option (a)

Showing 161 to 167 out of 167 Questions
12 13 14 15 16 17