183. The dielectric strength of air at 25?C and 76 cm of mercury is
A. 2.11 kV rms/cm
B. 21.1 kV rms/cm
C. 211 kV rms/cm
D. 2110 kV rms/cm

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184. Which of thermal protection switch is provided in power line system to protect against?
A. overload
B. temperature rise
C. short circuit
D. over voltage

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185. The following circuit breaker does not use pneumatic operating mechanism
A. air break circuit breaker
B. air blast circuit breaker
C. bulk oil circuit breaker
D. SF6 circuit breaker

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186. Fault diverters are basically
A. circuit breakers
B. fast switches
C. relays
D. fuse

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187. In a power system, the rate of rise of restriking voltage depends upon
A. switching condition only
B. circuit power factor only
C. both (a) and (b) above
D. none of these

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188. The voltage across the circuit breaker pole after final current zero is
A. restriking voltage
B. recovery voltage
C. supply voltage
D. none of these

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189. Bulk oil circuit breaker is suitable for voltage upto
A. 4 kV
B. 10 kV
C. 25 kV
D. 36 kV

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