Question 14Steam Plants - 1st Asst/Chief

The correct answer is A) limit controls. Limit controls are safety devices that are interlocked with the burner circuit to prevent start-up or cause a safety shutdown under unsafe firing conditions in a large automatic auxiliary boiler. These limit controls monitor parameters such as pressure, temperature, and fuel flow, and will interrupt the burner circuit if these parameters exceed safe limits. The other answer choices are incorrect because: B) Flame safeguard controls monitor the burner flame and shut down the burner if the flame is extinguished. C) Combustion controls regulate the air-fuel ratio for efficient combustion, but do not directly provide safety shutdown. D) Programming controls are the logic circuits that sequence the boiler's operation, but do not necessarily include the safety limit controls.