Power Systems MCQ Set 1
1. In nuclear power stations which nuclear reaction is performed?
a) Nuclear fission
b) Nuclear fusion
c) 90% fission and 10% fusion
d) 90% fusion and 10% fission
Answer
Answer: a [Reason:] Nuclear fission is the process in which heavy nucleus is split when it is bombarded by certain partials. Huge amount of energy is released during nuclfclear fission in form of heat and radiation.
2. Which particle is bombarded on heavy nucleus of nuclear fuel?
a) Electron
b) Proton
c) Neutron
d) Photon
Answer
Answer: c [Reason:] Nuclear fission involvs bombardment of certain particles on heavy nucleus causing it to split. All modern fission reactors uses neutron particles for this purpose because they are neutral in charge and so, they can make their way through the shells of electrons and then through the nucleus at low energy.
3. The critical mass for U235 fission reaction is about _______
a) 100Kg
b) 200 Kg
C) 50 kg
d) 10 kg
Answer
Answer: d [Reason:] For a chain reaction to occur the sample of the fissionable material should be large enough to capture the neutron internally. The minimum mass of fissionable material required to sustain a chain reaction is called the Critical Mass”. The critical mass varies for each reaction, for U235 fission reaction it is about 10 Kg.
4. The fuel mainly used in nuclear fission reactors are:
a) U235
b) U239
c) U233
d) U238
Answer
Answer: a [Reason:] The materials U235,U233 and Pu239 are called fissionable materials. From all the above mentioned fuels only U235 will fission in chain reaction.
5. Which fissionable nuclear fuel occur in nature?
a) Plutonium
b) Thorium
c) Uranium
d) 94239 Pu
Answer
Answer: c [Reason:] The only natural fissionable fuel occurring in our nature is Uranium, of which 99.3% is U238 and 0.7% is U235 and U234 is only a trace. Out of these isotopes only U235 will fission in chain reaction.
6. Which of the following has high fission percentage?
a) Pu239
b) U233
c) U235
d) U234
Answer
Answer: c [Reason:] U235 has higher fission percentage in comparison to others. U235 is only fissionable nuclear fuel found in nature, Pu239 and U233 are produced artificially. They are fissionable.
7. Reactors used for converting fertile materials to fissile materials are called _____
a) research and development reactor
b) production reactor
c) power reactors
d) slow reactors
Answer
Answer: b [Reason:] Research and development reactors are used for testing new reactor designs and research. Production reactors are used for converting fertile materials into fissile materials and Power reactors are used for generation of electrical energy.
8. Which statement about fast reactor is true?
a) These reactors are big in size so not easier to shield
b) Fast reactors can convert fertile materials to fissile materials
c) Fast reactors are easy to control
d) Heat transfer and cooling is very easy and simple
Answer
Answer: b [Reason:] Fast reactors can convert more fertile material to fissile materials with the result that the net fuel consumption for such reactors is much less. These reactors are small and compact and so easier to shield. Heat transfer and cooling problems in the core are accomplished due to high power density.
Power Systems MCQ Set 2
1. In which part of nuclear power plant steam is produced?
a) Boiler
b) Heat exchanger
c) Chamber across the reactor
d) Air preheater
Answer
Answer: b [Reason:] There is no boiler in nuclear power plant. The heat energy released in the reactor during nuclear fission is utilised to heat the coolant. This coolant is circulated through the heat exchanger to produce steam.
2. What is the main function of moderator?
a) It absorb the extra neutrons
b) It divert extra neutrons
c) It slow down the speed of fast neutrons
d) It absorb the heat energy caused by nuclear reaction
Answer
Answer: d [Reason:] Neutrons rejected during the fission process at a very high velocity of about 1.5 × 107 m/s. For more effective use in nuclear reactor it is desirable to slow down the fast neutrons to speed corresponding to the speed of molecules of gas at normal temperature and pressure. This is accomplished with the help of moderator.
3. Which of the following material is not used as moderator?
a) Oxygen
b) Ordinary water
c) Heavy water
d) Graphite
Answer
Answer: a [Reason:] At present the common moderator materials used are graphite, ordinary water and heavy water. Oxygen is not suitable to use due to its low density and the consequent small number of collision.
4. Which of the following part of nuclear reactor is used to control the rate of reaction.
a) Moderator
b) Control rods
c) Reflector
d) Coolant
Answer
Answer: b [Reason:] In a reactor the chain reaction is to be maintained at steady value during the operation of reactor. Also the reactor must be able to shutdown automatically under emergency conditions. All these requires control rods for control of reactor so as to prevent the melting of fuel rods, disintegration of coolant and destruction of reactor as the amount of energy released is enormous.
5. Which of the following is the most essential requirement of control rod material?
a) It must be light weight
b) It must be cheap
c) It must have high absorption capacity for neutrons
d) It must be very reflective to neutrons
Answer
Answer: c [Reason:] The function of control rod is to control the rate of nuclear reaction by absorption extra release neutrons. Chain reaction is controlled either by removing or inserting neutron absorbing materials. The materials used for control rods must have very high absorption capacity for entrance.
6. Which of the following can be used as both as coolant and moderator ?
a) Helium
b) Molten sodium
c) Lithium
d) Ordinary water
Answer
Answer: d [Reason:] A good coolant should not absorb neutrons, should be non-oxidizing, non-toxic, non corrosive, should have high chemical and radiation stability and good heat transfer ability. Ordinary water is used as both as coolant and moderator in boiling water reactor and pressurized water is used as both as coolant and moderator in pressurized water reactor.
7. In thermal reactors control is very easy in comparison to other reactors.
a) True
b) False
Answer
Answer: a [Reason:] In thermal reactor control his very easy because of relatively low power densities and longer in neutron lifetime.
8. The main body of reactor is called ______
a) Thermal shielding
b) Reactor vessel
c) Reflector
d) Biological shielding
Answer
Answer: b [Reason:] The reactor core, reflector and thermal shielding are all enclosed in the main body of reactor and is called reactor vessel or tank. It is strong walled container and provides the entrance and exit for the coolant. It also provides the passage for flow of coolant through and around the reactor core.
Power Systems MCQ Set 3
1. What is the main purpose of reactance diagram?
a) Load flow analysis
b) Falt analysis
c) Calculation of ratings of Alternators
d) Calculation of ratings of Transformers
Answer
Answer: b [Reason:] The main purpose of reactance diagram is fault analysis. Load flow analysis is done by the help of Impedance diagram. All these diagrams are made using symmetrical component analysis method on per phase basis.
2. Which of the following is not neglected during formation of reactance diagram from impedance diagram?
a) Resistance of various power system components
b) Static loads
c) Shunt component of Transformers
d) Reactance of alternators
Answer
Answer: d [Reason:] Reactance diagram is drawn by the help of symmetrical network of various power system components by neglecting resistance of various components, static loads like induction motors and shunt component of Transformers.
3. Impedance diagram is used for analysis of ____
a) Load flow
b) Alternator
c) Fault
d) Transmission Line
Answer
Answer: a [Reason:] Impidance diagram is made for the analysis of load flow. Fault analysis is doen by the help of reactance diagram. All these diagrams are made using symmetrical component analysis method on per phase basis.
4. Reactance diagram contains which of the following ?
a) Resistance of Alternator
b) Resistance of transformer winding
c) Induction motor’s equivalent corcuit
d) Inductive reactance of transmission lines
Answer
Answer: d [Reason:] Reactance diagram contains only reactance of synchronous machines, transmission line and Transformers. Static loads like induction motors are neglected in diagram.
5. Single line diagram does not represents:
a) Star connection of transformer winding
b) Delta connection of transformer winding
c) Neutral wire of transmission lines
d) Ratings of machines
Answer
Answer: c [Reason:] Single line diagram is a representation of balanced power system on per phase basis with neutral eliminated. Neutral wire is not shown in single line diagram. Winding connections (star or neutral) is represented beside the symbol of transformer with its Impidance and rating.
6. Single line diagram of which of the following power system is possible?
a) Power system with LLG fault
b) Power system with LG fault
c) Power system with LL fault
d) Balanced power system
Answer
Answer: d [Reason:] Only balanced power system can be represented by a single line diagram. Single line diagram is drawn on per phase basis. A power system with LLG, LG and LL faults becomes unbalanced and can not be represented in per phase basis.
7. In impedance diagram different power system elements are represented by symbols.
a) True
b) False
Answer
Answer: b [Reason:] In reactance diagram different power system elements are represented by their symmetrical networks.
8. A three phase transformer has a nameplate rating of 30 MVA, 230Y/69Y kV with a leakage -reactance of 10% and the transformer connection is wye-wye. Choosing a base of 30MVA and 230 kV on high voltage side, the transformer reactance referred to the low voltage side will be _______(in ohms).
a) 15.87 Ω
b) 157.8 Ω
c) 176.33 Ω
d) 17.67 Ω
Answer
Answer: a [Reason:] X Ω = Xpu*Xb(LV) = 0.1*158.87 = 15.87 Ω.
Power Systems MCQ Set 4
1. The transmission line equations are given by the below set of equations based on the line diagram as given. Identify A and B parameters.
Vs = A*Vr+B*Ir
Is = C*Vr+D*Ir
a) 1+YZ, Z
b) Z,Y
c) Y, 1+YZ
d) 1+YZ, Y-1+Z
Answer
Answer: a [Reason:] Using KVL to the line diagram,
Vs = (1+YZ)*Vr+Z*Ir
Is = Y*Vr+Ir.
2. The transmission line equations are given by the below set of equations based on the line diagram as given. Identify A and C parameters.
Vs = A*Vr+B*Ir
Is = C*Vr+D*Ir
a) 1+YZ, Z
b) Z,Y
c) 1+YZ, Y
d) 1+YZ, Y-1+Z
Answer
Answer: c [Reason:] Using KVL to the line diagram,
Vs = (1+YZ)*Vr+Z*Ir
Is = Y*Vr+Ir.
3. The transmission line equations are given by the below set of equations based on the line diagram as given. Identify A and D parameters.
Vs = A*Vr+B*Ir
Is = C*Vr+D*Ir
a) 1+YZ, 1
b) 1+YZ, Z
c) Y, 1+YZ
d) 1+YZ, Y-1+Z
Answer
Answer: a [Reason:] Using KVL to the line diagram,
Vs = (1+YZ)*Vr+Z*Ir
Is = Y*Vr+Ir.
4. The transmission line equations are given by the below set of equations based on the line diagram as given. Identify B and A parameters.
Vs = A*Vr+B*Ir
Is = C*Vr+D*Ir
a) 1+YZ, Z
b) Z,YZ+1
c) Z, 1+YZ
d) 1+YZ, Y-1+Z
Answer
Answer: b [Reason:] Using KVL to the line diagram,
Vs = (1+YZ)*Vr+Z*Ir
Is = Y*Vr+Ir.
5. The transmission line equations are given by the below set of equations based on the line diagram as given. Identify C and A parameters.
Vs = A*Vr+B*Ir
Is = C*Vr+D*Ir
a) 1+YZ, Z
b) Z,Y
c) Y, 1+YZ
d) 1+YZ, Y-1+Z
Answer
Answer: c [Reason:] Using KVL to the line diagram,
Vs = (1+YZ)*Vr+Z*Ir
Is = Y*Vr+Ir.
6. The transmission line equations are given by the below set of equations based on the line diagram as given. Identify D and A parameters.
Vs = A*Vr+B*Ir
Is = C*Vr+D*Ir
a) 1+YZ, Z
b) 1+ZY, 1
c) Y, 1+YZ
d) 1, 1+YZ
Answer
Answer: a [Reason:] Using KVL to the line diagram,
Vs = (1+YZ)*Vr+Z*Ir
Is = Y*Vr+Ir.
7. The transmission line equations are given by the below set of equations based on the line diagram as given. Identify A and B parameters and find AB value.
Vs = A*Vr+B*Ir
Is = C*Vr+D*Ir
a) (1+YZ)* Z
b) 1+YZ* Z
c) Y*( 1+YZ)
d) (1+YZ)*Y-1+Z
Answer
Answer: a [Reason:] Using KVL to the line diagram,
Vs = (1+YZ)*Vr+Z*Ir
Is = Y*Vr+Ir.
8. The transmission line equations are given by the below set of equations based on the line diagram as given. Identify A and B parameters and find ‘A*C’ value.
Vs = A*Vr+B*Ir
Is = C*Vr+D*Ir
a) (1+YZ)* Y
b) (1+YZ)* Z
c) Y*( 1+YZ)
d) (1+YZ)*Y-1+Z
Answer
Answer: a [Reason:] Using KVL to the line diagram,
Vs = (1+YZ)*Vr+Z*Ir
Is = Y*Vr+Ir.
9. The transmission line equations are given by the below set of equations based on the line diagram as given. Identify A and B parameters and find ‘A*D’ value.
Vs = A*Vr+B*Ir
Is = C*Vr+D*Ir
a) (1+YZ)
b) (1+YZ)* Z
c) 1
d) 0
Answer
Answer: a [Reason:] Using KVL to the line diagram,
Vs = (1+YZ)*Vr+ Z*Ir
Is = Y*Vr + Ir
AD = (1+YZ).
10. The transmission line equations are given by the below set of equations based on the line diagram as given. Identify A and B parameters and find ‘B*D’ value.
Vs = A*Vr+B*Ir
Is = C*Vr+D*Ir
a) (1+YZ)
b) (1+YZ)* Z
c) Z
d) YZ
Answer
Answer: c [Reason:] Using KVL to the line diagram,
Vs = (1+YZ)*Vr + Z*Ir
Is = Y*Vr + Ir
BD = Z.
11. The transmission line equations are given by the below set of equations based on the line diagram as given. Identify A and B parameters and find ‘B*C’ value.
Vs = A*Vr + B*Ir
Is = C*Vr + D*Ir
a) (1+YZ)
b) (1+YZ)* Z
c) 1
d) YZ
Answer
Answer: a [Reason:] Using KVL to the line diagram,
Vs = (1+YZ)*Vr+Z*Ir
Is = Y*Vr+Ir
BC = YZ.
12. The transmission line equations are given by the below set of equations based on the line diagram as given. Identify A and B parameters and find ‘C*D’ value.
Vs = A*Vr+B*Ir
Is = C*Vr+D*Ir
a) (1+YZ)
b) (1+YZ)* Z
c) Z
d) Y
Answer
Answer: a [Reason:] Using KVL to the line diagram,
Vs = (1+YZ)*Vr+Z*Ir
Is = Y*Vr+Ir
CD = Y*1 = Y.
13. The transmission line equations are given by the below set of equations based on the line diagram as given. Identify A and B parameters and find ‘AB-CD’ value.
Vs = A*Vr+B*Ir
Is = C*Vr+D*Ir
a) Z-Y+YZ2
b) (1+YZ)* Z
c) 1+YZ+YZ2
d) 1-YZ+ZY2
Answer
Answer: a [Reason:] Using KVL to the line diagram,
Vs = (1+YZ)*Vr+Z*Ir
Is = Y*Vr+Ir
AB-CD = (1+YZ)*Z-Y.
14. The transmission line equations are given by the below set of equations based on the line diagram as given. Identify A and B parameters and find ‘AD-BC’ value.
Vs = A*Vr+B*Ir
Is = C*Vr+D*Ir
a) Z-Y+YZ2
b) (1+YZ)* Z
c) YZ+YZ2
d) 1
Answer
Answer: d [Reason:] Using KVL to the line diagram,
Vs = (1+YZ)*Vr+Z*Ir
Is = Y*Vr+Ir
AD-BC = (1+YZ)-YZ = 1.
15. The transmission line equations are given by the below set of equations based on the line diagram as given. Identify A and B parameters and find ‘A*C*D’ value.
Vs = A*Vr+B*Ir
Is = C*Vr+D*Ir
a) ZY+(YZ)2
b) (1+YZ)* Z
c) YZ+YZ2
d) 1-YZ+ZY2
Answer
Answer: a [Reason:] Using KVL to the line diagram,
Vs = (1+YZ)*Vr+Z*Ir
Is = Y*Vr+Ir
ACD = (1+YZ)*ZY.
Power Systems MCQ Set 5
1. In medium transmission lines capacitive current is ____
a) Less than short transmission lines
b) Equal to short transmission lines
c) More than short transmission lines
d) More than long transmission lines
Answer
Answer: c [Reason:] Line to Earth capacitance of medium transmission line is more than that in short transmission line and less than that in long transmission line. Because of this the charging current of medium transmission line is more than that in short transmission line and less than that in long transmission line.
2. In actual the capacitance of line is ______
a) More at receiving end
b) More at sending end
c) Uniformly distributed over entire length
d) More in middle of sending end and receiving end
Answer
Answer: c [Reason:] Actually the capacitance of line is uniformly distributed over its entire length. To make calculations simple the capacitance of the system is assumed to be divided up and lumped in the form of capacitors shunted across the line at one or more points.
3. Charging current in medium transmission line is _____
a) Maximum at receiving end
b) Maximum at sending end
c) More in between sending and receiving end
d) Equal throughout the line
Answer
Answer: a [Reason:] The magnitude of capacitive current flowing at any point along the line is that required to charge the section of the line between the given point and receiving end. Hence, it has maximum value at the sending in and diminished at practically uniform rate down to zero at the receiving end.
4. In end condenser method of solution of medium transmission line, capacitance of the line is assumed to be _______
a) Distributed uniformly from sending end to receiving end
b) Lumped at the load end
c) Lumped at the generation end
d) Lumped at middle of generation and load end
Answer
Answer: b [Reason:] In end condenser method the capacitance of the line is assumed to be lumped at the load end. This method overestimates the effect of capacitance.
5. In nominal-T method of solution of medium transmission line, capacitance is assumed to be ____
a) Distributed uniformly from sending end to receiving end
b) Lumped at the load end
c) Lumped at the generation end
d) Lumped at middle of generation and load end
Answer
Answer: d [Reason:] In nominal- T method or middle condenser method of analysis of medium transmission line the whole of the line capacitance is assumed to be concentrated at the middle point of the line and half the line resistance and reactance to be lamp on either side.
6. In nominal-π method of solution of medium transmission line, capacitance is assumed to be:
a) Distributed uniformly from sending end to receiving end
b) Divided into two halves
c) Lumped at the generation end
d) Lumped at middle of generation and load end
Answer
Answer: b [Reason:] In nominal-π method of solution of medium transmission line the capacitance of each line conductor is assumed to be divided into two halves. One half being shunted between line conductor and neutral at the receiving in and other half at the sending end.
7. Medium transmission line operates below voltage level of 20 KV.
a) True
b) False
Answer
Answer: b [Reason:] The voltage limit of 20 KV is for short transmission lines. Medium transmission lines can operate for voltage more than 20 KV.
8. Which of the following is not a method for solution of medium transmission line?
a) End condenser method
b) Nominal-T method
c) Nominal-π method
d) Nominal-H method
Answer
Answer: d [Reason:] Actual method used for solution of medium transmission lines are end condenser method, nominal-T method and nominal π method.
9. In a nominal-π method the resistance of line is assumed to be ____
a) Distributed uniformly from sending end to receiving end
b) Divided into two halves
c) Lumped at the generation end
d) Lumped at middle of the line
Answer
Answer: d [Reason:] In nominal-π method the capacitance of each line conductor is assumed to be divided into two halves and the resistance of the line is assumed to be lumped in between them at the middle of the line.
10. In nominal-T method of solution of medium transmission line, resistance and inductive reactance of the line is divided into two half’s.
a) True
b) False
Answer
Answer: a [Reason:] In nominal-T method of solution of medium transmission line, the whole of the line capacitance is assumed to be concentrated at the middle point of the line and half the line resistance and reactance to be lumped on either side of it.
