An essential auxiliary in a gas turbine installation is?

• A. Air Heater
• B. Starting Motor
• C. Water Injection System
• D. Generator

Answer: (B)

Starting a gas turbine requires bringing the compressor up to speed before fuel can ignite. That initial rotation is provided by a starting motor, which spins the compressor through the accessory gear box until the turbine reaches the speed needed for stable combustion. Once ignition occurs and the turbine sustains itself, the starter is disengaged.

Air heaters help improve efficiency by heating incoming air, but the turbine can start without them. Water injection aids surge margin or NOx control, not basic starting. The generator is the main electrical output, not an auxiliary used to start the turbine. So the essential auxiliary is the starting motor.