In the system shown, the generator is delivering 1 p.u. power. The voltage behind transient reactance is 1.05 p.u. and infinite bus voltage is 1 p.u. If the system is subjected to a 3−ϕ fault on point P, the critical clearing angle is______electrical degrees.[H=5 MJ/MVA.f = 50 Hz]
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The series impendance matrix of a short three-phase transmission line in phase coordinates is ⎡⎢⎣ZsZmZmZmZsZmZmZmZs⎤⎥⎦. If the positive sequence impedance is (1 + j10) Ω, and the zero sequence impedance is (4 + j31) Ω, then the imaginary part of Zm(in Ω) is (upto to 2 decimal places).7
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A 10-bus power system consists of four generator buses indexed at G1, G2, G3, G4 and six load buses indexed as L1, L2, L3, L4, L5, L6. The generator-bus G1 is considered as slack bus, and the load buses L3 and L4 are voltage controlled buses. The generator at bus G2 cannot supply the required reactive power demand, and hence it is operating at its maximum reactive power limit. The number of non-linear equations required for solving the load flow problem using Newton Raphson method in polar form is14
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In a load flow problem solved by Newton-Raphson method with polar coordinates, the size of the Jacobian is 100×100. If there are 20 PV buses in addition to PQ buses and a slack bus, the total number of buses in the system is 61
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A cylindrical rotor synchronous generator has steady state synchronous reactance of 0.7 pu and subtransient reactance of 0.2 pu. It is operating at (1+ j0) pu terminal voltage with an internal emf of (1 + j0.7)pu. Following a three-phase solid short circuit fault at the terminal of the generator, the magnitude of the subtransient internal emf in p.u (rounded off to 2 decimal places) is 1.02
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For a power system:Line to line fault current=−j2.5 p.u.3−ϕ fault current =−j5 p.u. The positive and negative sequence reactances are
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Three 6.6 kV, 3-ϕ, 10 MVA alternators are connected to a common bus. Each alternator has a positive negative and zero sequence reactances as 0.15 p.u., 0.1 p.u.,0.05 p.u. respectively. A single line to ground fault occurs at point F, as shown in figure below.If is the fault current when all the alternator neutrals solidy grouned I′f is the fault current when only one neutral is solidly grounded and other two neutrals are isolated. Then the value of |If−I′f|=________kA.6.512
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Consider the network shown. Bus numbers and impedances are marked. An element having an impedance of 0.8Ω is connected between bus 2 and reference bus. Z22new becomes ___pu.0.218
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A three-phase short-circuit fault occurs at point F. in the system shown in figure below. The fault current is _____________A. 878.5
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For the given Y-bus matrix, the reactance diagram isYbus=⎡⎢⎣−j10+j5+j5+j5−j20+j10+j5+j10−j10⎤⎥⎦
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A 3-phase power system is represented by one line diagram as shown in the figure below: The ratings of equipments are the following: Genrator (G) : 15 MVA, 6.6 kV, X1 = 15%,X2 = 10%Transformer : 15 MVA, 6.6 kV delta/33 kV star,X1=X2=X0=6%Line reactance : X1=X2=2Ω and X0=6ΩIf a SLG fault occurs on bus bar B, then the fault current is _______ p.u.0
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A 100 kV, 2 micro sec rectangular surge on a line having a surge impedance of 300 Ω approaches a station at which concentrated earth capacitance is 3000 pF. The maximum value of transmitted value is___kV.178.32
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A three phase, 200 MVA, 11 kV generator has the following p.u. constants. The generator neutral is solidly grounded X1=X2=3X0=0.30 Ω. The ratio of the fault current due to three phase dead short circuit to that of L-G fault would be _____.0.78
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Consider the two power systems shown in Figure A below which are initially not interconnected, and are operating in steady state at the same frequency. Separate load flow solutions are computed individually for the two systems, corresponding to this scenario. The bus voltage phasors so obtained are indicated in figure A. These two isolated systems are now interconnected by a short transmission line as shown in figure B, and it is found that P1=P2=Q1=Q2=0. Figure A Figure BThe bus voltage phase angular difference between generator bus X and generator bus Y after the interconnection is
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A sub sequence network of a 3−ϕtransformer is given.Find the type of transformer connection?
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