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Overheating of relay contacts or contact born out is due to_______________? A. slow making and breaking of load circuit contacts B. foreign matter on the contact surface C. too low contact pressureD. all of the above
Shunt capacitance is neglected while considering______________? A. short transmission line B. medium transmission line C. long transmission line D. medium and long transmission lines
Ionization in circuit breaker is facilitated by___________? A. high temperature B. increase of mean free path C. increasing field strengthD. all of the above
A transmission line is protected by_____________? A. inrush protection B. distance protection C. time graded and current graded over current protectionD. both (B) and (C) E. none of the above
When a transmission line is energized, the wave that propagates on it is____________? A. current wave only B. voltage wave onlyC. Both (A) and (B) D. power factor wave only
Burden of a protective relay is the power______________? A. required to operate the circuit breakerB. absorbed by the circuit of relay C. developed by the relay circuit D. none of the above
The current zero interruption, in oil and air blast circuit breakers, is achieved by____________? A. lengthening of the gap B. cooling and blast effectC. both (A) and (B) D. deionizing the oil with forced air E. none of the above
The current zero interruption, in oil and air blast circuit breakers, is achieved by_______________? A. lengthening of the gap B. cooling and blast effectC. both A. and B D. deionizing the oil with forced air E. none of the above
The relay operating speed depends upon_________________? A. the spring tension B. the rate of flux built up C. armature core air gapD. all of the above
Relays can be designed to respond to changes in________________? A. resistance, reactance or impedance B. voltage and current C. light intensity D. temperatureE. all above