Deck 3: Casting Processes and Three Phase Induction Motors

Question 1

In centrifugal casting, a movable pouring basin is employed for the pouring of molten metal.

Answer 1

True

Question 2

The speed of rotation is almost double in semi centrifugal casting as compared to the true centrifugal casting.

Answer 2

False

Question 3

Which of the following moulds or moulding is also known as sodium silicate process.

A)shell moulding
B)permanent moulding
C)slush moulding
D)CO₂ moulding

Answer 3

CO₂ moulding

Question 4

How much percentage of sodium silicate (Na2SiO3) is added to the sand mixture in CO₂ moulding?

A)0 to 2 %
B)2 to 6 %
C)6 to 10 %
D)10 to 14 %

Question 5

How much time (in a minute) is usually required for the passing of CO₂ through the mould?

A)one
B)two
C)five
D)seven

Question 6

It is very safe to use CO₂ in CO₂ moulding, so it eliminates the use of any shielding apparatus.

Question 7

Which of the following additives are added to the sand in CO₂ moulding for the improvement in collapsibility of the sand?

A)copper oxide
B)wood flour
C)aluminium oxide
D)oil

Question 8

CO₂ moulding process is an ideal process, where speed and flexibility is the prime requirement.

Question 9

Moisture from the mould can be removed by using of dryer or heater in CO₂ moulding.

Question 10

CO₂ moulding is a kind of sand moulding, but it is not economical than the green sand moulding.

Question 11

Which of the following defect is not a gas defect?

A)blow holes
B)air inclusions
C)run out
D)pin hole porosity

Question 12

Which gas defect is caused by hydrogen in molten metal?

A)blow holes
B)air inclusions
C)open blows
D)pin hole porosity

Question 13

Cuts, washes, swell, drop etc. are the examples of which of the following casting defects?

A)gas defect
B)pouring material defect
C)moulding material defect
D)metallurgical defect

Question 14

When the molten metal leaks out of mould which defect occurs?

A)run out
B)misrun
C)fusion
D)drop

Question 15

The lower fluidity of molten material causes_______________    

A)misrun
B)cold shut
C)misrun & cold shut
D)fusion

Question 16

Defects caused by the chilling of the casting are known as?

A)hot spots
B)hot tears
C)shrinkage cavity
D)swell

Question 17

During melting process flux is added to react with impurities to form?

A)cavity
B)slag
C)cold shut
D)blow holes

Question 18

Which defect is caused due to the conversion of moisture to steam because of the heat of molten metal?

A)blow holes
B)open blows
C)air inclusions
D)cold shut

Question 19

Defect which occurs due to the solidification of casting is known as?

A)swell
B)misrun
C)metal penetration
D)shrinkage cavity

Question 20

The direction of rmf when a single phase supply is given to stator of three phase induction motor is?

A)zero
B)ns
C)2ns
D)-ns

Question 21

The direction of rmf when a three phase supply is given to stator of three phase induction motor is?

A)zero
B)ns
C)2ns
D)-ns

Question 22

Two three phase induction motors A and B are identical in all respects except that motor A has a larger air-gap than motor B. Which motor will have more no load current?

A)a
B)b
C)both a and b
D)neither a nor b

Question 23

Two three phase induction motors A and B are identical in all respects except that motor A has a larger air-gap than motor B. Which motor will have poorer power factor?

A)a
B)b
C)both a and b
D)neither a nor b

Question 24

Two three phase induction motors A and B are identical in all respects except that motor A has a larger air-gap than motor B. Which motor will have better full-load power factor?

A)a
B)b
C)both a and b
D)neither a nor b

Question 25

A three phase induction motor is sometimes calles a generalized transformer in so far as voltage and frequency transformation has been concerned. How a three phase induction motor operates when rotor frequency is equal to stator frequency?

A)it will not operate
B)it will operate as induction motor only
C)it will operate as induction generator
D)it will operate in braking mode