ALLIGATION OR MIXTURE PROBLEMS QUIZ

A three point starter is considered suitable for

Shunt as well as compound motors

All D.C. motors

Shunt motors

Shunt, compound and series motors

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In the dc motor the iron losses occur in

Armature

Brushes

Commutator

Field

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Which of the following in a dc motor, can sustain the maximum temperature rise?

Field winding

Slip rings

Commutator

Armature winding

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The most suitable motor for elevators is the ____ motor.

Differentially compuonded

Shunt

Series

Cummulative compounded

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The variable resistor shunting the field of a dc series motor is called a

Armature divertor

Potential divider

Voltage regulator

Field divertor

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If the speed of a dc shunt motor is increased the back emf of the motor will

Become zero

Increase

Remains same

Decrease

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For the same H.P. rating and full load speed, following motor has poor starting torque

Shunt

Series

Cumulatively compounded

Differentially compounded

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Which of the following law can be used to determine the direction of rotation of dc motor?

Fleming's left hand rule

Coloumb's law

Faraday's law

Lenz's law

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As there is no back e.m.f. at the instant of starting a D.C. motor, in order to prevent a heavy current from flowing though the armature circuit

A resistance is connected in series with armature

A high value resistor is connected across the field winding

A resistance is connected parallel to the armature

Armature is temporarily open circuited

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Excessive sparking at brushes may be caused due to

Worn bearings

Misaligment of machine

Loose coupling

Dirt on the commutator

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