Mini Mock on Power System & Electrical Machines: ESE 2018 for ESE & GATE EE Exams

Question 1

The figure shows a two-generator system supplying a load of P_D = 40 MW, connected at bus 2.

The fuel cost of generators G₁ and G₂ are:
C ₁ = 10,000 Rs / MWh and C₂ = 12,500 Rs/MWh and the loss in the line is P_loss_(pu) = 0.5

, where the loss coefficient is specified in pu on a 100 MVA base. The most economic power generation schedule in MW is

Question 2

For a power system network with n nodes, Z₃₃ of its bus impedance matrix is j0.5 per unit. The voltage at node 3 is 1.3 ∠–10 ° per unit. If a capacitor having reactance of –j3.5 per unit is now added to the network between node 3 and the reference node, the current drawn by the capacitor per unit is

Question 3

For a two machine system with losses, with the transfer impedance being resistive, the maximum value of the sending end power

and the maximum receiving end power

will occur at power angles

in such a manner that

Question 4

A uniformly distributed load on a distributor of length 500 m is rated at 1 A per metre length. The distributor is fed from one end at 220 V. The voltage drop at a distance of 400 metres from the feeding point is ________ V. (Assume a loop resistance of 2X10^-5Ω/m)

Question 5

A two bus system has loss coefficient as

Question 6

When a fault occurs in a power system the following sequence currents are recorded.
I_zero = -j1.123 p.u
I_positive = j1.923 p.u
I_negative = -j0.8 p.u
The fault is

Question 7

In induction type directional over current relay the driving torque is due to interaction of magnetic fields derived from

Question 8

A 75 NVA, 10 kV synchronous generator has X_d = 0.4 p.u. The X_d value (in p.u.) is a base of 100 MVA, 11 kV is

Question 9

A three phase, wound rotor induction motor is to be operated with slip energy recovery in the constant torque mode, when it delivers an output power P₀ at slop s. then theoretically, the maximum power that is available for recovery at the rotor terminals, is equal to

Question 10

Which of the following are the variable losses in a rotating machine?

Question 11

Consider the following statements:
The armature torque in a dc motor is a function of
1) Field flux
2) Armature current
3) Speed
4) Damping

Question 12

Consider the following statements:
As a three-phase induction motor is loaded from no-load to rated load.
1) There is an improvement in the power factor
2) The torque increases almost in proportion to slip
3) The air-gap flux falls sharply
Which of the above statements are correct?