1) When a transmission line is energized, the wave that propagates on it is____________? a. current wave only b. voltage wave only c. Both (A) and (B) d. power factor wave only
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2) Burden of a protective relay is the power______________? a. required to operate the circuit breaker b. absorbed by the circuit of relay c. developed by the relay circuit d. none of the above
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3) The current zero interruption, in oil and air blast circuit breakers, is achieved by____________? a. lengthening of the gap b. cooling and blast effect c. both (A) and (B) d. deionizing the oil with forced air e. none of the above
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4) The current zero interruption, in oil and air blast circuit breakers, is achieved by_______________? a. lengthening of the gap b. cooling and blast effect c. both A. and B d. deionizing the oil with forced air e. none of the above
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5) The relay operating speed depends upon_________________? a. the spring tension b. the rate of flux built up c. armature core air gap d. all of the above
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6) Relays can be designed to respond to changes in________________? a. resistance, reactance or impedance b. voltage and current c. light intensity d. temperature e. all above
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7) An efficient and a well designed protective relaying should have_____________? a. good selectivity and reliability b. economy and simplicity c. high speed and selectivity d. all of the above
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8) A differential relay measures the vector difference between_________________? a. two currents b. two voltages c. two or more similar electrical quantities d. none of the above
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9) Protective relays are devices that detect abnormal conditions in electrical circuits by measuring_____________? a. current during abnormal condition b. voltage during abnormal condition c. constantly the electrical quantities which differ during normal and abnormal conditions d. none of the above
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10) In a circuit breaker the basic problem is to________________? a. maintain the arc b. extinguish the arc c. transmit large power d. emit the ionizing electrons
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11) The voltage appearing across the contacts after opening of the circuit breaker is called__________voltage a. recovery b. surge c. operating d. arc e. none of the above
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12) Large internal faults are protected by_______________? a. merz price percentage differential protection b. mho and ohm relays c. horn gaps and temperature relays d. earth fault and positive sequence relays
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13) Directional relays are based on flow of____________? a. power b. current c. voltage wave d. all of the above
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14) Air blast circuit breaker is used for_____________? a. over currents b. short duty c. intermittant duty d. repeated duty
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15) Circuit breakers usually operate under______________? a. transient state of short-circuit current b. sub-transient state of short-circuit current c. steady state of short-circuit current d. after D.C. component has ceased
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16) D.C. shunt relays are made of_____________? a. few turns of thin wire b. few turns of thick wire c. many turns of thin wire d. many turns of thick wire
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17) Circuit breakers are essentially____________? a. current carrying contacts called electrodes b. arc extinguishers c. circuits to break the system d. transformers to isolate the two systems e. any of the above
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18) Circuit breakers are essentially______________? a. current carrying contacts called electrodes b. arc extinguishers c. circuits to break the system d. transformers to isolate the two systems e. any of the above
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19) In order that current should flow without causing excessive heating or voltage drop, the relay contacts should_________________? a. have low contact resistance b. be clean and smooth c. be of sufficient size and proper shape d. have all above properties
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20) Thermal overload relays are used to protect the motor against over current due to____________? a. short-circuits b. heavy loads c. grounds d. all of the above
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