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

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.)

33. Question

Two generator have cost functions F1 and F2 . Their incremental-cost characteristics are 

they need to deliver a combined load of 260MW. Ignoring the network losses, for economic operation operation, the generation P1 and P2 are

34. Question

Suppose IA,IB,IC are a set of unbalanced current phasors in a three- phase system. The phase -B zero sequence current IB0 = 0.1∠0º p.u. If a phase A current  IA = 1.1∠0º p.u. and phase C current  IC =(1∠120º + 0.1) p.u., then IB in p.u. is.

35. Question

In the fig shown, self impedance of two transmiision lines are 1.5j p.u. each and Zm = 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