Power Systems Objective Questions & Answers – Set 5

Which of the following statements is/are true?

Bonding is done at the both ends of the cable to reduce the

Under over excitation synchronous phase modifier works as

In a long transmission line, if we increase the length of the line, the parameters A and B respectively

A 3-phase, 110 kV coaxial XLPE insulated power cable delivering power at 50 Hz, has a capacitance of 125 nF/km. If the dielectric loss tangent of XLPE is 2*10^-4, then dielcetric power loss in this cable in W/km/phase is

A string insulator has 4 units. The voltage across the bottom most unit is 33.33% of total voltage. Its string efficiency is

Consider a three phase, 50 Hz, 11 kV distribution system. Each of the conductors is suspended by an insulator string having two identical porcelain insulators. The self capacitance of the insulators is 5 times the shunt capacitance between the link and ground. Find the voltage across the two insulators V1 and V2? (V1 = Voltage of disc nearest to the conductor)

Which of the following represents the sag(S) of a transmission line?

Which of the following method is used for changing power factor from leading to lagging

The corona loss on a particular system at 50 Hz is 1 kW/km per phase. What is the corona loss at 60 Hz in kW/km per phase?

A cable has the following characteristics, L = 0.201 µH/m and C = 196.2 pF/m. The velocity of wave propagation through cable is

A transmission line has a surge impedance of 400 Ω for a length of the line of 200 km. If the length of line is increased to 400 km, then its surge impedance is

The surge impedance of a 400 km long overhead transmission line is 420 Ω. For a 200 km length of the same line, the surge impedance will be

Which of the following statements is/are true? Corona is reduced by

A string type insulator has three units with self capacitance C and ground capacitance of 0.2 C having a string efficiency of

A guard ring is used in string type insulator having 3 units to improve string efficiency. Find the capacitance of metal link 2 if pin to earth capacitance of each unit is 1 F?

Which of the following statements is true? Corona loss increases with

If the conductor diameter decreases, inductance of the line,

Attenuation occurs due to

Power transmission lines are transposed to reduce

The insulation resistance of the 20 km long underground cable is 8 MΩ. Other things being same, the insulation resistance of 10 km long cable will be

For loss less line, find the ratio of length to the wave length of a signal for a phase shift of 0.05 radians?

A transmission line is operating under no load has ABCD parameters B = 100∠90° has a phase shift of 0.2 rad, how much shunt reactor is required for compensation of ferranti effect?

Phase shift occurs due to which of the following components?

Which of the following statements is/are true? Due to corona,

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

A 1- phase transmission line operating at 30 kV has radius of 1 cm and distance between conductors is 0.5 m. Assume m = δ =1, g = 21 kV/cm and frequency f = 50 Hz. Find the critical disruptive voltage?

Critical visual voltage is the voltage at which

A loss less transmission line has a length of 600 km, find the phase shift of voltage signal?

Critical disruptive voltage is a voltage at which