FAA Powerplant Written Practice Test

Which detection system operates without needing a power supply for detection?

1. Spot detection system

2. Thermocouple

3. Continuous loop system

4. Optical fire detection system

The correct answer is: Spot detection system

The spot detection system operates without needing an external power supply for detection because it relies on a physical sensor mechanism to detect heat or flame. In this type of system, when a predetermined temperature is reached, the sensor activates a switch that indicates the presence of fire. This activation is typically based on a direct thermal response rather than requiring continual power to monitor the environment. In contrast, other systems like the continuous loop system actively need a power source to continuously monitor temperature along various points in the loop. Thermocouples convert thermal energy into electric voltage, relying on power to relay information about temperature, while optical fire detection systems often depend on electronic components to interpret light signals indicative of a fire. Therefore, when evaluating the capability of different fire detection systems to function without a power supply, the spot detection system stands out as the one that can accomplish this task effectively.