Which sequence best describes a typical safe gas turbine start?

Which sequence best describes a typical safe gas turbine start?

• A. Light off fuel, ignite, purge lines, accelerate to idle.
• B. Purge combustor and lines, light off fuel, start igniters, accelerate to idle.
• C. Engage control interlocks, purge combustor and lines, precharge lubrication, start igniters, light off fuel, accelerate to idle, monitor sensors and ramp to full speed.
• D. Purge lines, ignite fuel, start combustor, ramp to full speed.

Answer: (C)

A safe start relies on a controlled sequence that clears any flammable mixture and preps all systems before bringing the turbine to operating speed. Begin by engaging the control interlocks to enforce safety logic and allow an orderly abort if something goes wrong. Next, purge the combustor and lines to remove any residual fuel vapors or air that could ignite unintentionally. Precharging the lubrication system ensures oil pressure is available to protect bearings as soon as rotation begins. With ignition hardware ready, start the igniters and then light off the fuel once ignition is confirmed. Finally, accelerate to idle and monitor key sensors, ramping to full speed only if all readings stay within safe limits. This combination of safeguards—interlocks, purge, lubrication precharge, ignition readiness, controlled light-off, and monitored ramp—is what makes the sequence safe. Other sequences skip one or more of these steps or put them in unsafe order (for example, igniting fuel before purge or before ignition readiness, or omitting lubrication precharge), which increases the risk of an unsafe start.

A safe start relies on a controlled sequence that clears any flammable mixture and preps all systems before bringing the turbine to operating speed. Begin by engaging the control interlocks to enforce safety logic and allow an orderly abort if something goes wrong. Next, purge the combustor and lines to remove any residual fuel vapors or air that could ignite unintentionally. Precharging the lubrication system ensures oil pressure is available to protect bearings as soon as rotation begins. With ignition hardware ready, start the igniters and then light off the fuel once ignition is confirmed. Finally, accelerate to idle and monitor key sensors, ramping to full speed only if all readings stay within safe limits. This combination of safeguards—interlocks, purge, lubrication precharge, ignition readiness, controlled light-off, and monitored ramp—is what makes the sequence safe. Other sequences skip one or more of these steps or put them in unsafe order (for example, igniting fuel before purge or before ignition readiness, or omitting lubrication precharge), which increases the risk of an unsafe start.