Time Left - 15:00 mins

GATE 2020: Power Systems Rapid Revision Quiz 1

Attempt now to get your rank among 822 students!

Question 1

A 2-bus system and corresponding zero sequencenetworks are shown in the figure.

The transformers T₁ and T₂ are connected as

Question 2

The direct axis and quadrature axis reactances of a salient pole alternator are 1.2 p.u and 1.0 p.u respectively. The armature resistance is negligible. If this alternator is delivering rated kVA at up of and at rated voltage then its power angle is

Question 3

A round rotor generator with internal voltage E₁ = 2.0 p.u. and X = 1.1 p.u. is connected to a round rotor synchronous motor with internal voltage E₂ = 1.3 p.u. and X = 1.2 p.u. The reactance of the line connecting the generator to the motor is 0.5 p.u. when the generator supplies 0.5 p.u. power, the rotor angle difference between the machines will be

Question 4

Two 3-phase, Y-connected alternators are to be paralleled to a set of common bus bars. The armature has a per phase synchronous reactance of 1.7 Ω and negligible armature resistance. The line voltage of the first machines is adjusted to 3300 V and that of the second machine is adjusted to 3200 V, the machine voltages are in phase at the instant they are paralleled. Under this condition, the synchronizing current per phase will be

Question 5

Two identical synchronous generators, each of 100 MVA, are working in parallel supplying 100 MVA at 0.8 lagging p.f. at rated voltage. Initially the machines are sharing load equally. If the field current of first generator is reduced by 5% and of the second generator increased by 5%, find the sharing of load (MW and MVAR) between the generators. Assume X_d = X_q = 0.8 p.u., no field saturation and rated voltage across load. Reasonable approximations may be made.

Question 6

A surge of 15 kV magnitude travels along a cable towards its junction with an overhead line. The inductance and capacitance of the cable and overhead line are respectively 0.3 mH, 0.4 μF and 1.5 mH, 0.012 μF per km. The voltage rise at the junction due to the surge is

822 attempts
2 upvotes
2 comments

Tags :

ESE & GATE EE Power Systems

Mar 14ESE & GATE EE