Which of the following motors is preferred for traction work?

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 of the following is an advantage of electric traction over other methods of traction?

A

Faster acceleration

B

No pollution problems

C

Better braking action

D

All of the above

Which of the following is the disadvantage of electric traction over other systems of traction?

A

Corrosion problems in the underground pipe work

B

Short time power failure interrupts traffic for hours

C

High capital outlay in fixed installations beside route limitation

D

Interference with communication lines

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 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

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

A

High efficiency operation

B

Reversibility

C

Variable speed drive

D

High starting torque

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 preferred for traction work?

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