What role does the centrifugal speed switch play in the APU?

The centrifugal speed switch is a crucial component in the Auxiliary Power Unit (APU) as it plays a significant role in controlling the sequence of electrical components based on turbine speed. When the APU starts up, the centrifugal speed switch monitors the rotational speed of the turbine. As the turbine reaches predetermined speeds, the switch activates or deactivates certain electrical components to ensure optimal operation of the APU.

This control mechanism is essential for maintaining the correct functioning of the APU, as it allows for precise timing of when specific systems, such as fuel valves, ignition, or generator output, should be engaged or disengaged. This ensures that the APU operates efficiently and safely, decreasing the risk of mechanical failure and enhancing performance during its operation.

In terms of the other options, regulating air intake pressure, monitoring oil temperature conditions, and operating the fuel pump assembly are all vital functions of various components in the APU, but they do not fall under the direct responsibility of the centrifugal speed switch. Its primary function is specifically tied to managing the relationship between the turbine speed and the electrical systems, making option B the correct choice.