Electrical Engineering: Power system MCQ

36. Question

The Bode magnitude plot for the transfer function vo(s) / vi(s) of the circuit is as shown.The value of R _____ Ω.

 




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37. Question

An alternator with internal voltage of 1∠δ p.u. and synchronous reactance of 0.4 p.u. is connected by a transmission line of reactance 0.1 p.u. to a synchronous motor having synchronous reactance 0.35 p.u. and internal voltage of 0.85 ∠δp.u. If the real power
supplied by the alternator is 0.866 p.u, then (δ1 – δ) is ______degrees.(round off to 2 decimal places)

(Machines are of non-salient type . Neglect resistances)




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38. Question

The figure shows the single line diagram of a power system with a double circuit transmission line. The expression for electrical power is 1.5 sin δ , where δ is the rotor angle. The system is operating at the stable equilibrium point with mechanical power equal to 1 pu. If one of the transmission line circuits is removed, the maximum value of δ , as the rotor swings is 1.221 radian. If the expression for electrical power with one transmission line circuit removed is Pmax sin δ , the value of P max , in pu is ________.




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39. Question

The positive, negative, and zero sequence reactances of a wye-connected synchronous generator are 0.2 pu, 0.2 pu, and 0.1 pu, respectively. The generator is on open circuit with a terminal voltage of 1 pu. The minimum value of the inductive reactance, in pu, required to be connected between neutral and ground so that the fault current does not exceed 3.75 pu if a single line to ground fault occurs at the terminals is _______ (assume fault impedance to be zero). (Give the answer up to one decimal place) 




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40. Question

Two single core power cables have total conductor resistance of 0.7Ω and 0.5Ω resp,and their insulation resistance (between core and sheath) are 600MΩ and 900MΩ resp, When the two cables are joined in series,the ratio of insulation resistance to conductor  resistance is_____ X 106 




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