a) The contact material only. b) The contact material and its vapour pressure. c) The circuit parameters only. d) The combination of (b) and (c). Ans: (d)
a) Increases in case of ABCD but decreases in OCB. b) Decreases in case of ABCD but decreases in OCB. c) Decreases in both the cases. d) Increases in both the cases. Ans: (b)
a) 35 kA b) 49 kA c) 70 kA d) 89 kA Ans: (d)
a) 5 to 40 b) 40 to 45 c) 45 to 20 d) None of the above Ans: (a)
a) Impedance relay b) Reactance relay c) Mho relay d) None of the above Ans: (d)
a) There is insulation between contacts. b) The oil between the breaker contacts has greater strength. c) Solid insulation is provided for insulating the contacts from earth. d) None of the above Ans: (c)
a) Increase in current, frequency and p.f. b) Increases in current reduction in frequency and p.f. c) Increase in current and frequency but reduction in p.f. d) None of the above. Ans: (b)
a) HV transmission lines only. b) HV cables only. c) HV transmission and cables. d) None of the above. Ans: (a)
a) Air blast C.B. b) Oil C.B. c) Vacuum C.B. d) Any one of the above. Ans: (c)
a) High vapour pressure and low conductivity properties. b) High vapour pressure and high conductivity properties. c) Low vapour pressure and high conductivity properties. d) Low vapour pressure and low conductivity properties. Ans: (a)