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GATE 2023 Power Systems Quiz 48

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Question 1

Two 50 Hz generating units operate in parallel within the same power plant and have the following ratings:

Unit 1: 500 MVA, 0.85 pf, 20 kN, 300 rpm, H1 = 5 MJ/MVA

Unit 2: 200 MVA, 0.9 pf, 20 kV, 1500 rpm, H2 = 5 MJ/MVA

The equivalent inertia constant H in MJ/MVA on 100 MVA base is

Question 2

A transmission line has equal voltages at the two ends maintained constant by two sources a third source is to be provided to maintain constant voltage equal to the end voltages either at the mid-point or 75% of distance from the sending end then the maximum power transfer capabilities from sending end in original case and the other two cases will be in the ratio?

Question 3

A 2 pole ,50Hz,11kV turbo generator has a rating of 60MW,power factor 0.85 lagging.its rotor has a moment of inertia of 8800 kg-m2 .The inertia constant in MJ per MVA and its momentum in MJ-sec/electrical degree respectively are?

Question 4

A 50 Hz generator is delivering 60% of max. power is to an infinite bus bar through a T.L. A fault occurs and power is reduced. During the fault 20% of maximum Power is transferred. When the fault is isolated the max. power that can be delivered is 75% of the original maximum value. Find the critical clearing angle (in degrees)?

Question 5

A 50 Hz, 4-pole, turbo-generator rated 100 MVA, 11 kV has an inertia constant of 9 MJ/MVA. Rotor accelerates when a mechanical input is suddenly raised to 70 MW for an electrical load of 40 MW. If the acceleration is maintained for 5 cycles, then what is the change in torque angle in electrical degrees______?

Question 6

The Generator rating of 200MVA, 11KV, 50Hz, 4-pole had an inertia constant of 6 MJ/MVA. The machine is operating at a load of 120 MW, when load is suddenly increases to 160 MW find the change in rotor speed (in rpm) ________if the retardation is maintained for 5 cycles.
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