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Solution for Live Quiz Session: Power System 2 Feb

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Question 1

A three phase, 33 kV oil circuit breaker is rated 1200 A,2000 MVA,3 secs. Then the making capacity is?

Question 2

When a fault occurs in a power system the following sequence currents are recorded.
IZero = –j1.246 pu ;
IPositive = j 2.046 pu ;
INegative = –j 0.8 pu.
The fault is

Question 3

A power system consists of an alternator connected to an infinite bus through transformer and short transmission line. A 3-phase fault occurs at the transmission line mid-point. The initial rotor angle is and mechanical input power is 1.2pu and inertia constant is 5MJ/MVA. Find the critical clearing time of the system.

Question 4

On the occurrence of an unsymmetrical fault, which sequence Impedance of transmission line is greater than the other one?

Question 5

In a power plant two machines are operating in parallel at 50Hz
Machine 1: 500MVA, 20kV, H1 = 5MJ/MVA
Machine 2: 200MVA, 20kV, H2 = 10MJ/MVA
Find the equivalent inertia constant H in MJ/MVA on 100MVA base

Question 6

A typical line has the following parameters;
A = D = 0.961.0
B = 8080Ω.
If the line supplies a load of 20 MW at 0.9 pf lag, 110 kV, the voltage regulation (in %) of the line is __________.

Question 7

A 150MVA, 11kV, 50Hz, 4-pole generator is having inertia constant of 5MJ/MVA. If the acceleration of rotor is 850 elec. degree/s2 for 4 cycles, then find the change in the speed of rotor at the end of transient period of 4 cycles?

Question 8

A 3–Phase alternator rated as 15 MVA 13.2 k V has solidly grounded neutral. Positive, negative and zero sequence reactance are 30%, 20%, and 10% respectively. If the neutral is infinitely Solidly grounded then evaluate the value the Fault in (kA) for Line-Line Fault occurs in the system?

Question 9

A generating station has a rated capacity to produce 160 MW of energy. If the maximum demand of the generating station is 90 MW, and the load factor is 72%, find the plant capacity factor.

Question 10

An insulator string consists of four insulators. The voltage drop across the units starting from the cross arm towards the power conductor is 4.36 kV, 8.52 kV, 13.68 kV and 17.44 kV respectively. Determine the string efficiency.
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Nov 19ESE & GATE EE