Which of the following resistances can be measured by conducting insulation resistance test on a synchronous motor ?

A synchronous motor installed at the receiving end substation operates with such an excitation that it takes power at lagging power factor. Now if the applied voltage of the synchronous motor goes down, the power factor of the synchronous motor will

A

remain same

B

go down

C

improve

D

none of the above

While starting a salient pole synchronous motor by induction motor action and connecting field discharge resistance across field, starting and accelerting torque is produced by

A

induction motor torque in field winding

B

induction motor torque in damper winding

C

eddy current and hysteresis torque in pole faces

D

reHetance motor torque due to saliency of the rotor

E

all of the above methods

A synchronous motor can be used as a synchronous capacitor when it is

A

under-loaded

B

over-loaded

C

under-excited

D

over-excited

A synchronous motor can develop synchronous torque

A

when under loaded

B

while over-excited

C

only at synchronous speed

D

below or above synchronous speed

The line insulation is the insulation level of the station equipment.

A

less than

B

same as

C

more than

D

proportional to

E

not directly related with

The insulation between windings and grounded core and the insulation between the windings of the same phase is

A

minor insulation

B

major insulation

C

either of the above

D

none of the above

Upto the critical radius of insulation, added insulation, will

A

Increase the heat loss

B

Decrease heat loss and will have no effect beyond that

C

Decrease heat flux

D

Reduce convection heat loss compared to conduction heat less

The overall resistance for heat transfer through a series of flat resistance, is the __________ of the resistances.

A

Average

B

Geometric mean

C

Product

D

Sum

Resistances can be measured with the help of

A

wattmeters

B

voltmeters

C

ammeters

D

ohmmeters and resistance bridges

E

all of the above

While starting a synchronous motor by induction motor action, field winding is usually

A

connected to D.C. supply

B

short-circuited by low resistance

C

kept open-circuited

D

none of the above

Which of the following resistances can be measured by conducting insulation resistance test on a synchronous motor ?

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