Write down specification and applications of Air blast C. B. and Vacuum C. B.

Write down specification and applications of Air blast C. B. and Vacuum C. B.
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1 Answer

Answer :

Specifications of Circuit Breaker: i) Service type: Indoor / Outdoor ii) No. of Poles: 1 or 3 iii) Nominal System Voltage: iv) Highest System Voltage: v) Rated normal current; vi) Rated short-circuit breaking current (rms): vii) Rated short-circuit making current (rms): viii) Rated short-time current withstand capability for 3 sec: ix) Rated insulation level: x) S. C. Rating: xi) No. of breaks per phase: xii) Operating air / gas pressure: xiii) Nominal frequency

Applications: 

Air Blast Circuit Breaker: Air blast circuit breakers are used in electrical systems operating at 132kV and above upto 400kV. 

Vacuum Circuit Breaker: Vacuum circuit breakers are used in electrical systems operating at 11kV, 25kV and 33kV.

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Out of the following fuels used in a furnace exhausting flue gas at a temperature of 600°C, the percentage stack loss will be maximum in case ofcomplete combustion of(A) Furnace oil with air(B) Furnace oil with oxygen(C) Blast furnace gas with air(D) Blast furnace gas with oxygen

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Explosion limit of blast furnace gas is 37 to 71% gas in gas-air mixture. It means that the blast furnace gas will explode when burnt in a confined space, if its concentration in the gas-air mixture is __________ percent. (A) < 37% (B) > 71% (C) In between 37 & 71% (D) None of these

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Which of the following fuel gases is heavier than air? (A) Blast furnace gas (B) Coke oven gas (C) Natural gas (D) Water gas

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Last Answer : Answer: A

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Air blast circuit breakers for 400 kV power system are designed to operate in (a) 100 microsecond (b) 50 millisecond (c) 0.5 sec (d) 0.1 sec

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For large power transformers, self oil cooled type or air blast type which of the following values of current density may be used ? (a) 1.0 to 1.2 A/mm2 (b) 1.5 to 2.0 A/mm2 (c) 2.2 to 3.2 A/mm2 (d) 3.2 to 4.2 A/mm2

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