For which of the following applications D.C. motors are still preferred?

Why are the D.C. motors preferred for traction applications?

A

Torque and speed are inversely proportional to armature current

B

Torque is proportional to armature current

C

Torque is proportional to square root of armature current

D

The speed is inversely proportional to the torque and the torque is proportional to square of armature current

Which one of the following is not necessarily the advantage of D.C. motors over A.C. motors?

A

Low cost

B

Wide speed range

C

Stability

D

High starting torque

Which of the following motors is preferred for tape-recorders?

A

Shaded pole motor

B

Hysteresis motor

C

Two value capacitor motor

D

Universal motor

Which of the following motors is preferred for traction work?

A

Universal motor

B

D.C. series motor

C

Synchronous motor

D

Three-phase induction motor

Which of the following motors is preferred when quick speed reversal is the main consideration?

A

Squirrel cage induction motor

B

Wound rotor induction motor

C

Synchronous motor

D

D.C. motor

Which of the following motors are preferred for overhead traveling cranes?

A

Slow speed motors

B

Continuous duty motors

C

Short time rated motors

D

None of the above

Which of the following motors is preferred when smooth and precise speed control over a wide range is desired?

A

D.C. motor

B

Squirrel cage induction motor

C

Wound rotor induction motor

D

Synchronous motor

Which of the following motors is preferred for boom hoist of a traveling crane?

A

Single phase motor

B

Synchronous motor

C

A.slip ring motor

D

Ward-Leonard controlled D.C. shunt motor

Which of the following motors is usually preferred for kiln drives?

A

Cascade controlled A.C. motor

B

Slip ring induction motor

C

Three phase shunt wound commutator motor

D

Any of the above

For a motor-generator set which of the following motors will be preferred?

A

Synchronous motor

B

Slip ring induction motor

C

Pole changing induction motor

D

Squirrel cage induction motor

For which of the following applications D.C. motors are still preferred?

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