Deck 5: Motor and Crane Technology: Understanding the Different Types and Applications

Question 1

Light duty cranes are generally used in

A)Power houses
B)Pumping stations
C)Auto mobile workshops
D)All of the above

Answer 1

All of the above

Question 2

The size of an excavator is usually expressed in terms of

A)Crowd motion
B)Travel in meters
C)Travel in metres
D)Angle of swing

Answer 2

Angle of swing

Question 3

The range of ratings of electric motor used for rolling mills is of the order of

A)10 to 25 kW
B)25 to 85 kW
C)85 to 400 kW
D)400 to 1000 kW

Answer 3

85 to 400 kW

Question 4

When an electric train is moving down a hill the DC motor operates as a DC

A)Series motor
B)Series generator
C)Shunt motor
D)Shunt generator

Question 5

Speed controlled by variation of field flux results in

A)Constant power Drive
B)Variable power Drive
C)Constant torture Drive
D)Variable torque Drive

Question 6

The slip power recovery scheme is used in induction motor for speed control in the range

A)Above synchronous speed
B)Below synchronous speed
C)Both above and below synchronous speed
D)None of the above

Question 7

The pair used for frequency converter is

A)Squirrel cage induction motor and synchronous motor
B)Sleep ring induction motor and a synchronous motor
C)Sleep ring induction motor and squirrel cage induction motor
D)All of the above

Question 8

The motor in close are used for collieries, chemical plant is

A)Flame proof type
B)Splash proof type
C)Totally enclosed type
D)Pipe ventilated type

Question 9

The motor enclosure used in wood-working industry is

A)Protected type
B)Totally enclosed fan cooled type
C)Flame proof type
D)Splash proof type

Question 10

The motor enclosure used for industrial purposes is

A)Protected type
B)Drip proof type
C)Totally enclosed type
D)Open type

Question 11

Ball-bearings are

A)Used up to 75 kW motors
B)Of long life and low friction loss
C)Costlier and noisy particularly at high speed motor
D)All of the above

Question 12

Sleeve bearings

A)Are normally of bronze
B)Have self lubricating properties
C)Are used where noise is to be avoided
D)All of the above

Question 13

Hot bearings of a DC motor may be caused by

A)Poor ventilation
B)Incorrect voltage
C)Loose coupling
D)Lack of or dirty lubricant

Question 14

The least expensive drive is

A)Belt drive
B)Rope drive
C)Chain drive
D)Any of the above

Question 15

For very high speed ratio the indispensable drive is

A)Direct drive
B)Rope Drive
C)Chain drive
D)Any of the above

Question 16

15 minute rated motors are suitable for

A)Light duty cranes
B)Medium duty cranes
C)Heavy duty cranes
D)All of the above

Question 17

For medium duty cranes the short time rating motor used is

A)10 minutes
B)15 minutes
C)30 minutes
D)any of the above

Question 18

The cost of an induction motor will increase as

A)Horse power rating increases but rpm decreases
B)Horse power rating decreases but rpm increases
C)Horse power rating and operating speed increases
D)Horse power rating and operating speed decreases

Question 19

Which of the following motors has series characteristics?

A)Shaded Pole motor
B)Repulsion motor
C)Capacitor start motor
D)None of the above

Question 20

Which of the following motors is preferred for boom host of a travelling crane?

A)Single phase motor
B)Synchronous motor
C)AC slip ring motor
D)Ward Leonard controlled DC shunt motor

Question 21

For crane travel which off the following motors is normally used?

A)Synchronous motor
B)DC differential compound motor
C)Ward Leonard controlled DC shunt motor
D)AC slip ring motor

Question 22

Which of the following happens when start Delta starter is used ?

A)Starting voltage is reduced
B)Starting current is reduced
C)None of the above
D)Both A and B

Question 23

The characteristics of drive for crane hoisting and lowering are which off the following?

A)Precise control
B)Smooth movement
C)Fast speed control
D)All of the above

Question 24

In ........the speed can be varied by changing the position of brushes

A)Slip ring motor
B)Schrage motor
C)Induction motor
D)Repulsion motor

Question 25

In which of the following applications variable speed operation is preferred?

A)Exhaust fan
B)Ceiling fan
C)Refrigerator
D)Water pump