What is the role of the centrifugal switch in the APU ignition system?

The role of the centrifugal switch in the APU ignition system is to disconnect the ignition when certain RPMs are reached. This functionality is vital for ensuring safe and efficient operation of the Auxiliary Power Unit (APU). As the APU reaches a predetermined speed, the centrifugal switch activates, cutting off the ignition system. This prevents the APU from continuing to ignite fuel unnecessarily at high speeds, which could lead to engine damage or inefficiencies.

Understanding the centrifugal switch’s function helps emphasize the importance of effective ignition control in turbine engines, ensuring that they operate within safe parameters and utilize fuel efficiently once the desired operational speed is attained. By disconnecting the ignition at higher RPMs, the system minimizes the risk of unburned fuel reaching the exhaust, thereby increasing overall engine performance and safety.