# Electrical Engineering: Power system MCQ

##### 31. Question

A transmission line is being protected by distance protection. 80% of the line is being protected. The transfer reactance is 0.2 p.u. A solid 3-φ, fault occurred at the end of the transmission line. The minimum level of fault current to activate the relay

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##### 32. Question

The normal – π circuit of a transmission line is shown in the figure.

Impedance Z = 100∠80º and reactance X = 3300Ω . The magnitude of the characteristic impedance of the transmission line, in Ω, is ______. (Give the answer up to one decimal place.)

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##### 33. Question

Two generator have cost functions F_{1} and F_{2} . Their incremental-cost characteristics are

they need to deliver a combined load of 260MW. Ignoring the network losses, for economic operation operation, the generation P_{1} and P_{2} are

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##### 34. Question

Suppose I_{A},I_{B},I_{C} are a set of unbalanced current phasors in a three- phase system. The phase -B zero sequence current I_{B0} = 0.1∠0º p.u. If a phase A current I_{A} = 1.1∠0º p.u. and phase C current I_{C} =(1∠120º + 0.1) p.u., then I_{B} in p.u. is.

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##### 35. Question

In the fig shown, self impedance of two transmiision lines are 1.5j p.u. each and Z_{m} = 0.5j p.u. is the mutual impedance.Bus voltage shown in fig are in p.u.Given that δ>0 , the maximum steady state real power that can be transfered in p.u. from Bus -1 to Bus -2 is

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