ELECTRICAL MACHINES QUIZ

When two DC series motors are connected in parallel, the resultant speed is

more than normal speed.

zero.

normal speed.

less than normal speed.

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The no load and full load speed of DC mototr are 1400 rpm and 1200 rpm respectively. What is the percentage speed regulation of the motor?

18.25%.

15.30%.

14.28%.

16.67%.

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Induction motors normally use cast aluminium rotor because aluminium is

cheaper in cost.

lighter in weight.

of low resistivity.

easy to cast owing to its low melting point and is easily available.

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Which of the following represents the rotating losses of machine?

All of the them

Eddy current losses

Hysteresis losses

Friction and windage losses

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In induction motor especially the cage rotors slots are nearly parallel to shaft axis. This is called

crawling.

slip.

cogging.

skewing.

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What type of connection is made in between the inter-pole and the field winding?

Series.

Parallel.

None of the options.

Compound.

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Find the developed torque DC Series Motor having armature resistance of 0.2 Ω and taking armature current of 60 A is connected to 250 V supply. Considered brush drop of 1 V each.

133.22 N-m

234.76 N-m.

cant be determined.

266.20 N-m.

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Hysteresis loss will depends on

f1.6

f²

f

f³

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In an alternator, voltage drops occurs in

armature resistance, leakage reactance, armature reaction and earth connection.

armature resistance only.

armature resistance, leakage reactance and armature reaction.

armature resistance and leakage reactance.

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In a DC series generator, the terminal voltage with increase in load will

decrease

remain nearly constant

increase to rated voltage and then may decrease

increase gradually and then stay at rated voltage

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