Power Systems Objective Questions & Answers – Set 12
Power Systems Objective Questions & Answers
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An alternator having an induced emf of 1.6 pu is connected to an infinite bus of 1 pu. If the bus bar has reactance of 0.6 pu and alternator has reactance of 0.2 pu, what is the maximum power that can be transferred?
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The sequence components of the fault current are as follows: I_{R1} = j1.5 pu, I_{R2} = j0.5 pu, I_{R0} = j1. The type of fault is
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A generating station has a maximum demand of 100 MW, a load factor of 60% and a plant capacity factor of 50%. The reserve capacity of the plant is
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In thermal power stations, economiser will
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An over current relay, having a current setting of 125% connected to a supply circuit through a current transformer of ratio 400/5. The pick up value is
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For 800 MJ stored energy in the rotor at synchronous speed, what is the inertia constant H for a 50 Hz, four pole turbo generator rated 100 MVA, 11 kV?
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Equal area criterion gives the information regarding
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Steady state stability of a power system is improved by
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Which of the following is/are the disadvantages of phase modifiers?
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An isolated synchronous generator with transient reactance equal to 0.1 pu on a 100 MVA base is connected to the high voltage bus through a step up transformer of reactance 0.1 pu on a 100 MVA base. The fault level at the bus is
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If a generator of 250 MVA rating has an inertia constant of 6 MJ/MVA, its inertia constant on 100 MVA base is
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For which one of the following types of motors, is the equal area criterion for stability applicable?
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An over current relay, having a current setting of 125% connected to a supply circuit through a current transformer of ratio 500/5. The plug setting multiplier for a fault current of 5 kA is
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Lightning arresters are used for
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Which one of the following relays has the capability of anticipating the possible major fault in a transformer?
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The rating of fuse wire is always expressed in
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If the inertia constant H = 10 MJ/MVA for a 50 MVA generator, the stored energy is
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The pu parameters for a 500 MVA machine on its own base are: Inertia, H = 20 pu; reactance X = 2 pu. The pu values of inertia and reactance on 100 MVA common base, respectively, are
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In a 220 kV system, the inductance and capacitance up to the circuit breaker location are 25 mH and 0.025 µF respectively. The value of resistor required to be connected across the breaker contacts which will give no transient oscillations, is
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If the inertia constant H = 8 MJ/MVA for a 50 MVA generator, the stored energy is
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Mho relay is usually employed for protection of
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The inertia constant of 100 MVA, 50 Hz, 4 pole generator is 10 MJ/MVA. If the mechanical input to the machine is suddenly raised from 50 MW to 75 MW, the rotor acceleration will be equal to
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Maximum power capacity of a transmission line can be increased by
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Lightning arresters are made up of which material?
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Two identical synchronous machines having same inertia constant are connected in parallel and swinging together. The effective inertia constant is 4 MJ/MVA. Then each machine has inertia constant of
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Normally Z bus matrix is a
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Making and breaking currents of 3 phase AC circuit breakers in power system are respectively in what form?
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Stock bridge dampers are used in case hill areas to over come the which problem?
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If a 500 MVA, 11 kV 3phase generator at 50 Hz feeds through a transfer impedance of (0+j0.605) Ω/phase, an infinite voltage also at 11 kV, then the maximum steady state power transfer on the base of 500 MVA and 11 kV is
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Which of the following transformer is used in sub station for operating a protective relay?