When two D.C. generators are running in parallel an equalizer bar is used

When two D.C. series generators are running in parallel, an equalizer bar is used

A

To increase the speed and hence generated e.m.f.

B

To increase the series flux

C

So that two similar machines will pass approximately equal currents to the load

D

To reduce the combined effect of armature reaction of both machines

Two generators are running in parallel. One of the generators may run as motor for which of the following reasons?

A

The direction of that generator is reversed

B

The speed of that generator is increased

C

The field of that generator is weakened

D

That generator takes large share of loads

A lattice phase equalizer is a constant equalizer which satisfies the equation?

A

Z1Z2 = Ro

B

Z1 + Z2 = Ro

C

1/Z1+1/Z2 = Ro

D

Z1Z2 = Ro2

While running two compound motors in parallel, we connect equalizer ring between ___________

A

Two armatures

B

Two fields

C

Two load points

D

Anywhere

A steel and a copper bar are joined end to end. The area of the steel bar is half the area of the copper bar. Their lengths are equal to 10cm each. Temperature of free ends of steel & copper rod are 0°C & 100°C respectively. KS = 50 J/smK & KC =384 J/smK. Calculate equivalent thermal conductivity of the combined bar.

A

63°C

B

63K

C

336°C

D

36K

The length, Young’s modulus and coefficient of thermal expansion of bar P are twice that of bar Q. what will be the ration of stress developed in bar P to that in bar Q if the temperature of both bars is increased by the same amount?

A

2

B

8

C

4

D

16

The length, coefficient of thermal expansion and Youngs modulus of bar A are twice of bar B. If the temperature of both bars is increased by the same amount while preventing any expansion, then the ratio of stress developed in bar A to that in bar B will be ___________

A

2

B

4

C

8

D

16

A steel bar 2 m long, 20 mm wide and 10 mm thick is subjected to a pull of 2 kN. If the same bar is subjected to a push of 2 kN, the Poisson’s ratio of the bar in tension will be __________ the Poisson's ratio for the bar in compression.

A

Equal to

B

Less than

C

Greater than

D

None of these

Two D.C. shunt generators, each with armature resistance of 0.02 ohm and field resistance of 50 ohm run in parallel and supply a total current of 1000 amperes to the load circuit. If their e.m.fs. are 270 V and 265 V, their bus bar voltage will be

A

270 V

B

267.5 V

C

265 V

D

257.4 V

Commercially, which of the following generators is called turbo-alternators or turbo-generators?

A

salient pole rotor synchronous generators

B

cylindrical pole rotor induction generators

C

salient pole rotor induction generators

D

cylindrical rotor synchronous generators

When two D.C. generators are running in parallel an equalizer bar is used

Related Questions