X hits on this document

41 views

0 shares

0 downloads

0 comments

5 / 15

Q.28:- Based on the cohesive energy of an ionic solid, which of the following is not a property of the ionic solid?

(a)

It forms relatively stable and hard crystals

(b)

It is a poor electric conductor

(c)

It has a higher vaporization temperature

(d)

None of the above.

Q.29:- If the wave-form of the voltage impressed on the primary of a Y- bank contains a 5th harmonic, the wave-forms of the resultant voltages of primary and the secondary would be

PrimarySecondary

(a)

Peakedpeaked

(b)

Peakedflat-topped

(c)

Flat-toppedpeaked

(d)

Flat-toppedflat-topped

Q.30:- In a self-excited induction generator, to keep the frequency of generated voltage constant with the increase in load the speed of the induction machine should be

(a)

Increased.

(b)

Decreased.

(c)

Maintained less than the rated synchronous speed.

(d)

Maintained more than the rated synchronous speed.

Q.31:- The speed of a universal motor can be controlled by

(a)

introducing a variable resistance in series with the motor

(b)

tapping the field at various points

(c)

centrifugal mechanism

(d)

all of the above steps

Q.32:- A large a.c. generator, supplying to n infinite bus, has a sudden short-circuit occurring at it’s the voltage behind the transient reactance to remain constant immediately after the fault, the acceleration of the generator rotor is

(a)

inversely proportional to the moment of inertia of the machine

(b)

inversely proportional to the square of the voltage

(c)

directly proportional to the square of the short-circuit current

(d)

Directly proportional to the short-circuit power.

Q.33:- An electric train employing a dc series motor is running at a fixed speed, when a sudden slight drop in the mains voltage occurs. This would result in

(a)

drop in speed and rise in current

(b)

rise in speed and drop in current

(c)

rise in speed and rise in current

(d)

Drop in speed with current unaltered.

Q.34:- Ball mill is used in power plants using

(a)

multi-stage expansion

(b)

water softening

(c)

fly ash removal from flue gases

(d)

Pulverized fuel firing

Document info
Document views41
Page views41
Page last viewedSun Dec 11 06:52:27 UTC 2016
Pages15
Paragraphs474
Words3968

Comments