Bundled conductors are used for EHV transmission lines primarily for reducing the

A)     Corona loss

B)      Surge impedance of the line

C)      Voltage drop across the line

D)     Copper loss

Installation of capacitors at suitable locations and of optimum size in a distribution system results in

I. Improved voltage regulation.
II. Reduction in distribution power losses.
III. Reduction of KVA rating of distribution transformers.
Select the correct answer using codes given below:

A)     1 alone

B)      1 and 2

C)      1,2 and 3

D)     3 alone

In a three unit insulator string, voltage across the lowest unit is 17.5kV and string efficiency is 84.28%. the total voltage across the string will be equal to

A)     8.825 kV

B)      44.25 kV

C)      88.25 kV

D)     442.5 kV

The surge impedance of a 3 phase, 400kV transmission line is 400Ω. The surge impedance loading (SIL) is

A)     400 MW

B)      100 MW

C)      1600 MW

D)     200 MW

If a travelling-wave travelling along a loss-free overhead line does not result in any reflection after it has reached the far end, then the far end of the line

A)     Open circuited

B)      Short circuited

C)      Terminated in to a resistance equal to surge impedance of the line

D)     Terminated in to a capacitor

A travelling wave 400/1/50 means crest value of

A)     400 V with rise time 1/50 S

B)      400 kV with rise time 1 S and fall time 50S

C)      400 kV with rise time 1 µS with fall time 50µS

D)     400MV with rise time 1µS and fall time 50µS

Consider the following statements:Surge impedance loading of a transmission line can be increased by

I. Increasing its voltage level
II. Addition of lumped inductance in parallel
III. Addition of lumped capacitance in series
IV. Reducing the length of line
Which of these statements are correct?

A)     1 and 3

B)      1 and 4

C)      2 and 4

D)     3 and 4

The load current in short circuit calculation are neglected because

I. Short circuit currents are much larger than load currents
II. Short circuit currents are greatly out of phase with load currents
Which of these statements is/are correct?

A)     Neither 1 nor 2

B)      2 alone

C)      1 alone

D)     1 and 2

In pump storage hydropower plant, the electrical machine is made to work alternately as generator and motor. The efficiency of the generator working at the same electrical power level is

A)     Greater than that as motor

B)      Equal to that as motor

C)      Less than that as motor

D)     Greater or less than that as motor depending on the type of machine

In a thermal nuclear reactor

 I. The purpose of moderator is to slowdown fast neutrons produced due to fusion.
II. The moderator material must have low molecular weight.
III. Ordinary water can be used as moderator with natural uranium as fuel.
IV. The multiplication factor is kept slightly greater than unity during its normal functioning.
Which of these statements are correct?

A)     1 and 3

B)      3 and 4

C)      1,2 and 3

D)     1,2 and 4

In the HVDC system, the ac harmonics which gets effectively eliminated with 12 pulse bridge converters, are

A)     Triplen harmonics

B)      Triplen and fifth harmonics

C)      Triplen, fifth and seventh harmonics

D)     Fifth and seventh harmonics

The per-unit impedance of a circuit element of 0.15. if the base kV and base MVA are halved, then the new value of the per-unit impedance of the circuit element will be

A)     0.075

B)      0.15

C)      0.30

D)     0.60

The per-unit impedance of an alternator corresponding to base values 13.2 kV and 30 MVA is 0.2 pu. The p.u. value of the impedance for base values 13.8 kV and 50 MVA in p.u. will be

A)     0.131

B)      0.226

C)      0.305

D)     0.364

In a 220kV system, the inductance and capacitance up to the circuit breaker location are 25mH and 0.025µF respectively. The value of resistor required to be connected across the breaker contacts which will give no transient oscillations, is

A)     25Ω

B)      250Ω

C)      500Ω

D)     1000Ω

The speed regulation parameter R of a control area is 0.025 HZ/MW and load frequency constant D is 2 MW/Hz. The area frequency response characteristics (AFRC) is

A)     42 MW/Hz

B)      40 MW/Hz

C)      20 MW/Hz

D)     2 MW/Hz

The principal information obtained from load flow studies in a power system are

I. Magnitude and phase angle of the voltage at each bus
II. Reactive and real power flows in each of the lines
III. Total power loss in the network
IV. Transient stability limit of the system

Select the correct answer using the codes given below:

A)     1 and 2

B)      3 and 4

C)      1,2 and 3

D)     2 and 4

Three generators rated 100 MVA, 11 kV have an impedance of 0.15 pu each. If in the same plant, these generators are being replaced by a single equivalent generator, the effective impedance of equivalent generator will be

A)     0.05 pu

B)      0.15 pu

C)      0.25 pu

D)     0.45 pu

If all the sequence voltages at the fault point in a power system are equal, then the fault is a

A) Three-phase fault
B) Line to ground fault
C) Line to line fault
D) Double line to ground fault

Corona losses are minimised when

A)     Conductors size is reduced

B)      Smooth conductor is used

C)      Sharp points are provided in the line hardware

D)     Current density is conductors is reduced

The good effect of corona on overhead lines is to

A)     Increase the line carrying capacity due to conducting ionized air envelop around the conductor

B)      Increase the power factor due to corona loss

C)      Reduce the radio interference from the conductor

D)     Reduce the steepness of surge fronts