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Stability Analysis 1) What is the value of transient stability limit? a. Higher than steady state stability limit b. Lower than steady state stability limit. c. Depending upon the severity of load d. All of these e. None of these ANSWER: Lower than steady state stability limit. 2) By using which component can the transient stability limit of a power system be improved? a. Series resistance b. Series capacitor c. Series inductor d. Shunt resistance ANSWER: Series capacitor 3) What is transient stability limit? a. The maximum flow of power through a particular point in the power system without loss of stability when small disturbances occur. b. The maximum power flow possible through a particular component connected in the power system. c. The maximum flow of power through a particular point in the power system without loss of stability when large and sudden disturbances occur d. All of these e. None of these ANSWER: The maximum flow of power through a particular point in the power system without loss of stability when large and sudden disturbances occur

4) Which among the following methods is used for improving the system stability?

a. Increasing the system voltage b. Reducing the transfer reactance c. Using high speed circuit breaker d. All of these e. None of these ANSWER: All of these

5) What is steady state stability limit? a. The maximum flow of power through a particular point in the power system without loss of stability when small disturbances occur. b. The maximum power flow possible through a particular component connected in the power system. c. The maximum flow of power through a particular point in the power system without loss of stability when sudden disturbances occur d. All of these e. None of these ANSWER: The maximum flow of power through a particular point in the power system without loss of stability when small disturbances occur.

6) Which among these is a classification of power system stability? a. Frequency stability b. Voltage stability c. Rotor angle stability d. All of these e. None of these ANSWER: All of these 7) The stability of the power system is not affected by which among these? a. Generator reactance b. Line losses c. Excitation of generators

d. All of these e. None of these ANSWER: Line losses 8) What is power system stability? a. The maximum power flow possible through a particular component connected in the power system. b. The ability of the power system to regain the state of operating equilibrium point when the system is subjected to any disturbances. c. It is a phenomenon in which a power system losses its operating equilibrium when subjected to large disturbances. d. All of these e. None of these ANSWER: The ability of the power system to regain the state of operating equilibrium point when the system is subjected to any disturbances. 1. The over voltage surges in power systems me be caused by A. Lightning B. Resonance C. Switching D. All of the above ✔ View Answer D. All of the above 2. The critical clearing time of a fault is power system is related to A. Reactive power limit B. Short circuit limit C. Steady-state stability limit D. Transient stability limit ✔ View Answer D. Transient stability limit 3. Our system stability is least affected by A. Reactance of generator B. Input torque C. Losses

D. Reactants of transmission line ✔ View Answer C. Losses 4. Which portion of the our system is least prone to faults? A. Alternator B. Transformer C. Overhead lines D. Underground cable ✔ View Answer A. Alternators 5. The domains of power system where directional overcurrent relay is indispensable are A. In case of parallel feeder protection B. In case of ring main feeder protection C. Both A and B D. None of the above ✔ View Answer C. Both A and B 6. The stability of the power system is not affected by A. Generator reactance B. Line reactance C. Excitation of generators D. Line losses ✔ View Answer D. Line losses 7. The Power Systems are operated with power angle around A. 10o B. 30o C. 70o D. 80o ✔ View Answer B. 30o

8. Power system stability is defined as A. That attribute of the system or part of the system which enables it to develop restoring forces between the elements there of equal or greater than disturbing forces so as to restore a state of equilibrium between the elements B. The maximum power flow possible through some particular point in the system when the entire or part of the system is disturbed C. Both A and B D. Neither A or B ✔ View Answer A. That attribute of the system or part of the system which enables it to develop restoring forces between the elements there of equal or greater than disturbing forces so as to restore a state of equilibrium between the elements 9. Stability limit of a power system is defined as A. That attribute of the system or part of the system which enables it to develop restoring forces between the elements there of equal or greater than disturbing forces so as to restore a state of equilibrium between the elements B. The maximum power flow possible through some particular point in the system when the entire or part of the system is disturbed C. Both A and B D. Neither A or B ✔ View Answer B. The maximum power flow possible through some particular point in the system when the entire or part of the system is disturbed 10. Steady-state stability of a power system is the ability of the power system to

A. Maintain voltage at the rated voltage level B. Maintain frequency exactly at 50 Hz C. Maintain a spinning reserve margin at all times D. Maintain synchronism between machines and on external tie lines ✔ View Answer D. Maintain synchronism between machines and on external tie lines 11. Steady-state stability of a power system is improved by A. Reducing fault clearing time B. Using double circuit line instead of single circuit line C. Single pole switching D. Decreasing generator inertia ✔ View Answer B. Using double circuit line instead of single circuit line 12. The critical clearing time of a fault is power system is related to A. Reactive power limit B. Short circuit limit C. Steady-state stability limit D. Transient stability limit ✔ View Answer D. Transient stability limit 13. With fault clearing time, the transient stability limit of a power system A. Increases B. Decreases C. First increases then decreases D. First decreases and then increases ✔ View Answer B. Decreases 14. Transient disturbances are caused by

A. Sudden load changes B. Switching operations C. Fault in the power system D. All of the above ✔ View Answer D. All of the above

15. The transient stability limit of a power system can be appreciably increased by introducing A. Series inductance B. Shunt inductance C. Series capacitance D. Shunt capacitance ✔ View Answer C. Series capacitance

Swing Equation Swing Curve 1) Why are the series capacitors used? a. Improve the voltage b. Reduce the fault level c. Compensate for line inductive reactance and improve the stability of the power system. d. Improves the power factor ANSWER: Compensate for line inductive reactance and improve the stability of the power system. Which among these is related to the critical clearing time of a fault in a power system? - Published on 14 Oct 15 a. Transient stability limit b. Steady state stability limit c. Frequency limit d. All of these e. None of these ANSWER: Transient stability limit 9) Which among these cannot be determined from equal area criterion? - Published on 14 Oct 15 a. Critical clearing angle b. Critical clearing time c. Transient stability limit d. Both (a) and (b) e. All of these ANSWER: Critical clearing time 10)

ANSWER: All of these 11)

ANSWER: One machine and infinite bus bar 12) Which stability information is obtained from the equal area criterion? - Published on 14 Oct 15 a. Absolute stability b. Transient stability c. Steady state stability d. Both (b) and (c) e. All of these ANSWER: Absolute stability

13) Under what condition is the system stable under equal area criterion? - Published on 14 Oct 15 a. The area under the curve Pa – δ curve must increase to ∞. b. The area under the curve Pa – δ curve must become equal to 1 c. The area under the curve Pa – δ curve must reduce to zero. d. None of these Answer Explanation Related Ques ANSWER: The area under the curve Pa – δ curve must reduce to zero. Explanation: No explanation is available for this question! ________________________________________ 14) Why are the series capacitors used? - Published on 14 Oct 15 a. Improve the voltage b. Reduce the fault level c. Compensate for line inductive reactance and improve the stability of the power system. d. Improves the power factor

Answer Explanation Related Ques ANSWER: Compensate for line inductive reactance and improve the stability of the power system. Explanation: No explanation is available for this question! ________________________________________ 15) Which among the following methods are used to improve steady state stability? - Published on 14 Oct 15 a. Reducing the reactance between the transmission and receiving points. b. By using bundled conductors. c. By increasing the excitation of generator or motor or both. d. All of these e. None of these Answer Explanation Related Ques ANSWER: All of these Explanation: No explanation is available for this question! ________________________________________ 16) Which curve represents the reluctance power in the following power angle curve of a machine? - Published on 14 Oct 15 a. Curve A b. Curve B c. Curve C d. Curve A and curve B e. All the above Answer Explanation Related Ques ANSWER: Curve C Explanation: No explanation is available for this question! ________________________________________ 17) What is the range of ‘δ’ for stable operation? - Published on 14 Oct 15 a. 0° < δ < 45° b. 45° < δ < 90° c. 0° < δ < 90° d. 0° < δ < 120° Answer Explanation Related Ques ANSWER: 0° < δ < 90° Explanation: No explanation is available for this question! ________________________________________ 18) At what value of ‘δ’ the maximum power transfer takes place? - Published on 14 Oct 15 a. 45 °

b. 90 ° c. 120 ° d. 180 ° Answer Explanation Related Ques ANSWER: 90 ° Explanation: No explanation is available for this question! ________________________________________ 19) What is power angle equation of synchronous machines? - Published on 14 Oct 15 a. An equation between electrical power generated to the angular displacement of the rotor b. An equation between mechanical power generated to the angular displacement of the rotor c. An equation between electrical power generated to the angular displacement of stator windings d. An equation between mechanical power generated to the angular displacement of stator windings Answer Explanation Related Ques ANSWER: An equation between electrical power generated to the angular displacement of the rotor Explanation: No explanation is available for this question! ________________________________________ 20) Which point on the graph represents the steady state stability limit of the system? - Published on 14 Oct 15 a. Point A b. Point B c. Point C d. Point D Answer Explanation Related Ques ANSWER: Point A 21) What will be the inertia constant H, for a water wheel generator having a speed less than 200 rpm? - Published on 14 Oct 15 a. 2 - 4 b. 2 - 3 c. 1 - 2 d. 5 - 6 Answer Explanation Related Ques ANSWER: 2 - 3 Explanation: No explanation is available for this question! ________________________________________ 22) What are the main applications of the swing curves? - Published on 14 Oct 15

a. Designing the rotor field windings b. Designing the protective devices c. Used to limit the size of the machine d. All of these e. None of these Answer Explanation Related Ques ANSWER: Designing the protective devices Explanation: No explanation is available for this question! ________________________________________ 23) What information does the swing curve provide? - Published on 14 Oct 15 a. Stability of the system. b. Performance of the machine c. The rotor performance d. All of these e. None of these Answer Explanation Related Ques ANSWER: Stability of the system. Explanation: No explanation is available for this question! ________________________________________ 24) What kind of differential equation is swing equation? - Published on 14 Oct 15 a. Linear second order b. Non linear first order c. Linear first order d. Non linear second order Answer Explanation Related Ques ANSWER: Non linear second order Explanation: No explanation is available for this question! ________________________________________ 25) What is / are the major assumptions made in the calculation of swing equations? - Published on 14 Oct 15 a. Damper windings are neglected b. The machine is lossless c. The machine has to run at synchronous speed d. Both (a) and (b) e. All of these Answer Explanation Related Ques ANSWER: Both (a) and (b) 35) What does the swing equation describe? - Published on 19 Oct 15 a. The relative motion of rotor with the field windings of the machine

b. The relative motion of the rotor with respect to stator field as a function of time. c. The relative motion of stator field with the rated frequency of the machine d. The performance curve of the machine Answer Explanation Related Ques

________________________________________ 36) What is the result of frequency instability? - Published on 19 Oct 15 a. Voltage collapse b. Frequency swings c. Tripping of generating units d. Both (b) and (c) e. All of these Answer Explanation Related Ques ANSWER: Both (b) and (c) Explanation: No explanation is available for this question! ________________________________________ 37) What is frequency stability? - Published on 19 Oct 15 a. To maintain steady frequency following severe disturbance resulting in the imbalance between transformer and load b. To maintain steady frequency following severe disturbances resulting in the imbalance between generators and load c. To maintain a steady frequency in all the protection components and the transmission lines. d. Both (a) and (b) e. All of these Answer Explanation Related Ques ANSWER: To maintain steady frequency following severe disturbances resulting in the imbalance between generators and load Explanation: No explanation is available for this question! ________________________________________ 38) Which among the following phenomenon is generally associated with voltage stability? - Published on 19 Oct 15 a. Temporary load reduction b. Voltage is reduced c. Voltage collapses d. All of these e. None of these Answer Explanation Related Ques ANSWER: All of these Explanation: No explanation is available for this question! ________________________________________ 39) What is the main cause of voltage instability?

- Published on 19 Oct 15 a. Generators b. Transformers c. Loads d. Line losses Answer Explanation Related Ques ANSWER: Loads Explanation: No explanation is available for this question! ________________________________________ 40) What is voltage stability? - Published on 19 Oct 15 a. To maintain steady voltages at all the buses after the occurrence of fault. b. To maintain steady voltages at all the buses before the occurrence of fault. c. To maintain the system frequency after the severe disturbances d. All of these e. None of these Answer Explanation Related Ques ANSWER: To maintain steady voltages at all the buses after the occurrence of fault. ________________________________________ 1) On what factors does the transient stability depend on? - Published on 19 Oct 15 a. Initial operating state b. Severity of disturbances c. Voltage instability d. Both (a) and (b) e. All of these Answer Explanation Related Ques

ANSWER: Both (a) and (b) Explanation: No explanation is available for this question! ________________________________________ 42) What is / are the cause(s) for transient disturbance? - Published on 19 Oct 15 a. Sudden load changes b. Faults in the power system

c. Switching operations d. All of these e. None of these Answer Explanation Related Ques

ANSWER: All of these Explanation: No explanation is available for this question! ________________________________________ 43) Which among these phenomenons is / are associated with angle stability? - Published on 19 Oct 15 a. Imbalance between the two generator torque b. Stability or synchronism is lost c. Surplus energy is stored up in the rotating masses d. All of these e. None of these Answer Explanation Related Ques

ANSWER: All of these Explanation: No explanation is available for this question! ________________________________________ 44) What is the value of transient stability limit? - Published on 19 Oct 15 a. Higher than steady state stability limit b. Lower than steady state stability limit. c. Depending upon the severity of load d. All of these e. None of these Answer Explanation Related Ques

ANSWER: Lower than steady state stability limit.

Explanation: No explanation is available for this question! ________________________________________ 45) By using which component can the transient stability limit of a power system be improved? - Published on 19 Oct 15 a. Series resistance b. Series capacitor c. Series inductor d. Shunt resistance Answer Explanation Related Ques

ANSWER: Series capacitor Explanation: No explanation is available for this question! ________________________________________ 46) What is transient stability limit? - Published on 19 Oct 15 a. The maximum flow of power through a particular point in the power system without loss of stability when small disturbances occur. b. The maximum power flow possible through a particular component connected in the power system. c. The maximum flow of power through a particular point in the power system without loss of stability when large and sudden disturbances occur d. All of these e. None of these Answer Explanation Related Ques

ANSWER: The maximum flow of power through a particular point in the power system without loss of stability when large and sudden disturbances occur Explanation: No explanation is available for this question! ________________________________________ 47) Which among the following methods is used for improving the system stability?

- Published on 19 Oct 15 a. Increasing the system voltage b. Reducing the transfer reactance c. Using high speed circuit breaker d. All of these e. None of these Answer Explanation Related Ques

ANSWER: All of these Explanation: No explanation is available for this question! ________________________________________ 48) What is steady state stability limit? - Published on 19 Oct 15 a. The maximum flow of power through a particular point in the power system without loss of stability when small disturbances occur. b. The maximum power flow possible through a particular component connected in the power system. c. The maximum flow of power through a particular point in the power system without loss of stability when sudden disturbances occur d. All of these e. None of these Answer Explanation Related Ques

ANSWER: The maximum flow of power through a particular point in the power system without loss of stability when small disturbances occur. Explanation: No explanation is available for this question! ________________________________________ 49) Which among these is a classification of power system stability? - Published on 19 Oct 15 a. Frequency stability b. Voltage stability

c. Rotor angle stability d. All of these e. None of these Answer Explanation Related Ques

ANSWER: All of these Explanation: No explanation is available for this question! ________________________________________ 50) The stability of the power system is not affected by which among these? - Published on 19 Oct 15 a. Generator reactance b. Line losses c. Excitation of generators d. All of these e. None of these Answer Explanation Related Ques

ANSWER: Line losses

51) What is power system stability? - Published on 19 Oct 15 a. The maximum power flow possible through a particular component connected in the power system. b. The ability of the power system to regain the state o...