Electrical Studys

1] On which of the following effects of electric current a fuse operates?

1 pointA. Photoelectric effectB. Electrostatic effectC. Heating effectD. Magnetic effect

2] The steady state stability of the power system can be increased by

1 pointA. Connecting lines in parallelB. Connecting lines in seriesC. Using machines of high impedanceD. Reducing the excitation of machines

3] Air blast circuit breakers for 400 kV power system are designed to operate in

1 pointA. 100 microsecondB. 50 millisecondC. 0.5 secD. 0.1 sec

4] Which of the following parameter can be neglected for a short line?

1 pointA. InductanceB. CapacitanceC. ResistanceD. Reactance

5] ________ relay is preferred for phase fault on short transmission line.

1 pointA. Induction typeB. ReactanceC. ImpedanceD. None of the above

6] In order that current should flow without causing excessive heating or voltage drop, the relay contacts should

1 pointA. Have low contact resistanceB. Be clean and smoothC. Be of sufficient size and proper shapeD. Have all above properties

7] A transmission line is protected by

1 pointA. Inrush protectionB. Distance protectionC. Time graded and current graded over current protectionD. Both (B) and (C)

8] The arc voltage produced in A.C. circuit breaker is always

1 pointA. In phase with the arc currentB. Lagging the arc current by 90°C. Leading the arc current by 90°D. None of the above

9] To protect most of the electrical equipment handling low power, the types of relays used are

1 pointA. ThermocoupleB. Electronic and bimetallicC. Both (A) and (B)D. None of the above

10] A.C. network analyzer is used to solve problems of

1 pointA. Load flowB. Load flow and short-circuitC. Load flow and stabilityD. Load flow, short-circuit and stability

11] Protective relays are devices that detect abnormal conditions in electrical circuits by measuring

1 pointA. Current during abnormal conditionB. Voltage during abnormal conditionC. Constantly the electrical quantities which differ during normal and abnormal conditionsD. None of the above

12] Overheating of relay contacts or contact born out is due to

1 pointA. Slow making and breaking of load circuit contactsB. Foreign matter on the contact surfaceC. Too low contact pressureD. All of the above

13] An efficient and a well designed protective relaying should have

1 pointA. Good selectivity and reliabilityB. Economy and simplicityC. High speed and selectivityD. All of the above

14] D.C. shunt relays are made of

1 pointA. Few turns of thin wireB. Few turns of thick wireC. Many turns of thin wireD. Many turns of thick wire

15] Arc in a circuit behaves as

1 pointA. An inductive reactanceB. A capacitive reactanceC. A resistance increasing with voltage rise across the arcD. A resistance decreasing with voltage rise across the arc

16] When a wave propagates on a transmission line, it suffers reflection several times at

1 pointA. TappingB. Load endC. Sending endD. Sending and other end

17] The delay fuses are used for the protection of ________.

1 pointA. MotorsB. Power outlet circuitsC. Fluorescent lampsD. Light circuits

18] Ionization in circuit breaker is facilitated by

1 pointA. High temperatureB. Increase of mean free pathC. Increasing field strengthD. All of the above

19] The current zero interruption, in oil and air blast circuit breakers, is achieved by

1 pointA. Lengthening of the gapB. Cooling and blast effectC. Both (A) and (B)D. Deionising the oil with forced air

20] The main function of a fuse is to

1 pointA. Protect the lineB. Open the circuitC. Protect the applianceD. Prevent excessive currents

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