Minimum voltage regulation occurs when the power factor of the load is

A single phase transformer has a maximum efficiency of 90% at full load and unity power factor. Efficiency at half load at the same power factor is -

A

87.8%

B

86.7%

C

88.26%

D

88.9%

If in a synchronous motor, driving a given mechanical load and drawing current at a leading power factor from constant voltage supply its field excitation is increased, its power factor

A

will become more

B

will become less

C

will remain unchanged

D

none of the above.

If in a synchronous motor, driving mechanical load and drawing current at lagging power factor from constant voltage supply, its field excitation is increased, then its power factor

A

become more

B

become less

C

remain constant

D

none of the above

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

A power supply which has voltage regulation of ___________ is unregulated power supply

A

0%

B

5%

C

10%

D

8%

When the axis of load lies in the plane of rivet group, then the most heavily loaded rivet will be the one which (where, Fa is the load shared by each rivet due to axial load and Fm is the shearing load due to moment in any rivet.)

A

Is at the maximum distance from CG of the rivet group

B

Is at the minimum distance from CG of the rivet group

C

Gives the maximum angle between the two forces Fa and Fm

D

Gives the minimum angle between the two forces Fa and Fm

In testing a pile by load test, pile platform is loaded with one and half times the design load and a maximum settlement is noted. The load is gradually removed and the consequent rebound is measured. For a safe pile, the net settlement (i.e. total settlement minus rebound) per tonne of test load should not exceed

A

10 mm

B

15 mm

C

20 mm

D

25 mm

Negative voltage regulation is indicative that the load is

A

capacitive only

B

inductive only

C

inductive or resistive

D

none of the above

The voltage regulation in magnetic amplifier type voltage regulator is effected by

A

Electromagnetic induction

B

Varying the resistance

C

Varying the reactance

D

Variable transformer

If Q is load factor, S is shape factor and F is factor of safety in elastic design, the following:

A

Q = S + F

B

Q = S - F

C

Q = F - S

D

Q = S × F

Minimum voltage regulation occurs when the power factor of the load is

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