Question

When does master controller comes into action?

(a) When there is variation in steam flow rate

(b) When there is variation in fuel supply

(c) When there is variation in steam pressure

(d) When there is variation in draught fans

The question was asked in an interview for job.

Question is from Principle of Automatic Control of Combustion topic in division Steam Power Plant of Energy Engineering

Answer 1

The correct answer is (c) When there is variation in steam pressure

To explain I would say: The master controller comes into action when there is variation in steam pressure and it goes down below the required level. This activates the servo motor coupled to the vanes of induced draught fan which opens the air damper slightly. Simultaneously the secondary fan air damper also opens proportionately.