DC Generators Objectives Part 06

101 . A generator may lose residual due to heating.

102 . Level compound generator with interpoles is not a cross field machine.

103 . In case of cross field machine, the amplification ration may be of the order of 10,000.

104 . The major application of cross field machines is in control system.

105 . Compensating winding in amplidyne is provided to reduce magnetizing effect of armature reaction on the control winding flux.

106 . For a 6-pole wave wound dc generator the number of brushes will be 2.

107 . Dummy coil in a dc generator is provided to reduce mechanical unbalance.

108 . Drop in speed of a dc generator due to increase in load can be compensated by increasing input to the prime mover.

109 . When P is the number of poles in a lap wound dc generator, the number of brushes will be P.

110 . In case of a 4-pole lap wound 32 coils dc generator the pole pitch will be 16.

111 . Two dc shunt generators are operating in parallel. The easiest way to shift load from one generator to the other is by adjusting field rheostats.

112 . For a generator if constant losses are equal to variable losses, the efficiency of the generator will be maximum.

113 . Electromagnetic torque and speed are in opposite directions in case of shunt generators.

114 . The generated emf and current are in the same direction in case of dc generators.

115 . Hysteresis losses in a dc machine are given by 𝐵1.6fV. where V stands for volume of iron part.