Synopsis of Electrical Engineering

1.        When a pumped storage power plant is operated in conjunction with a steam power plant a.        The operating cost of the steam plant becomes optimum b.       Load factor of the steam plant is increased c.        Chances of the tripping of the system decreases because of the use of two heterogeneous types of plants d.       Operation of the storage plant in the pumping mode during the low-load period improves the steam-plant stability 2.        Usage of materials in components of a nuclear reactor:     Graphite is used in moderators;   Boron is used in control rods ;   Sodium is used as a coolant ;  Concrete is used as a shield 3.        A 100km long transmission line is loaded at 110kV. If the loss of line is 15MW and the load is 150MVA, the resistance of the line is a.        8.06 ohms per phase b.       0.806 ohms per phase c.        0.0806 ohm per phase d.       80.6 ohms per phase 4.        Two insulator discs of identical capacitance value C ma

Important Multiple Choice questions on Power Systems 1.        For transmission line which one of the following relations is true? A)      AD-BC=1 B)       –AD-BC=1 C)       AD-BC=-1 D)      AD-BC=0 2.        For a given base voltage and base volt-amp, the per unit impedance value of an element is X. what will be the per-unit impedance value of this element when the voltage and volt-amp bases are both doubled? A)      4X B)       2X C)       X D)      0.5X 3.        A 3-phase transmission line has its conductors at the corners of an equilateral triangle with side 3m. the diameter of each conductor is 1.63 cm. the inductance of the line per phase per km is A)      1.232 mH B)       1.182 mH C)       1.093 mH D)      1.043 mH 4.        A cable has inductance of 0.22mH per km and capacitance of 0.202 micro farads per km. the surge impedance of the cable is A)      28 ohms B)       33 ohms C)       42 ohms D)      50 ohms 5.        The capacitanc

Important Multiple Choice Questions On Power Systems 1.        Plug-setting of a relay can be altered by varying A)      Number of ampere-turns B)       Air gap of magnetic path C)       Adjustable back up stop D)      None of these 2.        If the time of operation of a relay for unity TMS is 10 sec, the time of operation of 0.5 TMS will be A)      20 Sec B)       5 Sec C)       10 Sec D)      None of these 3.        Where the voltages are high and current to be interrupted is low, the breaker proffered is A)      Air blast CB B)       Oil CB C)       Vacuum CB D)      Any of these 4.        Resistance switching is normally employed in A)      All breakers B)       Bulk oil breakers C)       Minimum oil breakers D)      Air blast circuit breakers 5.        For protection of rotating machines against lightning surges a combination of A)      Lighting conductor and capacitors are used B)       Lighting conductor and lighting arrestors

Important multiple choice questions on power systems 1.        Which one of the following statements is true? A)      Steady state stability limit is greater than transient state stability limit B)       Steady state stability limit is equal to transient state stability limit C)       Steady state stability limit is less than the transient stability limit D)      No generalisation can be made regarding the equality of otherwise of the steady state stability limit and transient stability limit 2.        If the integral control of a single area system, when  the system frequency error is reduced to zero A)      The integrator output and the speed changer position attains a constant value B)       The integrator output increases but the speed changer position also comes down C)       The integrator output decreases and the speed changer position also comes down D)      The integrator output decreases but the speed changer position moves up 3.        The steady-st

Important Multiple Choice Questions On Power Systems 1. With 100 % inductive shunt compensation, the voltage profile is flat for 100% loading line 50% loading line Zero loading of line None of these 2. For a long uncompensated line the limit to the line loading is governed by Thermal limit Voltage drop Stability limit Corona loss 3. Series capacitive compensation in EHV transmission lines is used to Reduce the line loading Improve   the stability of the system Reduce the voltage profile Improves the protection of the line 4. The main consideration for higher and higher operating voltage of transmission is to Increase the efficiency of transmission Reduce power losses Increase power transmission capability Both (A) and (B) above 5. The inertia constant H of a machine of 200MVA is 2 p.u. its value corresponding to 400MVA will be 4 2 1 0.5 6. A 500MVA, 11kV synchronous generator has 0.2 p.u. synchronous re

Important multiple choice questions on power system 1.        A line trap in carrier current relaying tuned to carrier frequency presents A)      High impedance to carrier frequency but low impedance to power frequency B)       Low impedance to both carrier and power frequency C)       High impedance to both carrier and power frequencies D)      Low impedance to carrier frequency and high impedance to power frequency 2.        The use of fast acting relays and circuit breakers for clearing a sudden short circuit on a transmission link between generator and the receiving end bus improves the transient stability of the machine because A)      Short circuit current becomes zero B)       Post-fault transfer impedance attains a value higher than that during the fault C)       Ordinate of the post-fault power-angle characteristic is higher than that of during fault characteristic D)      Voltage behind the transient reactance increases to a higher value 3.        A