Which type of oil temperature sensor is used that is supplied with electrical current by the aircraft DC power system?

Which type of oil temperature sensor is used that is supplied with electrical current by the aircraft DC power system?

• A. Thermocouple Based Oil Sensor
• B. Electrical Resistance Type Oil Thermometer
• C. Infrared Oil Thermometer
• D. Capacitance Oil Temperature Probe

Answer: (B)

The main concept is that oil temperature sensing in aircraft often uses an electrical resistance sensor fed by the DC power system. An electrical resistance type oil thermometer uses a metal element whose resistance changes predictably with temperature. The system biases the sensor with a small, known DC current (chosen to minimize self-heating), and the instrument reads the resulting voltage drop (or a bridge output). Because resistance vs. temperature is well-characterized, that voltage change maps directly to oil temperature. This arrangement is robust, accurate, and well-suited to the harsh engine environment, making it a common choice for continuous, electrical power–fed measurements from the aircraft DC system. Other sensor types either generate a signal without requiring a DC current to power the sensor element (thermocouples produce a voltage from temperature differences and need appropriate compensation), measure something other than the actual oil bulk temperature (infrared sensors read surface radiation and aren’t suitable for sealed oil in an engine), or rely on capacitance changes that typically use different excitation schemes (like AC) rather than a simple DC-powered resistance measurement.

The main concept is that oil temperature sensing in aircraft often uses an electrical resistance sensor fed by the DC power system. An electrical resistance type oil thermometer uses a metal element whose resistance changes predictably with temperature. The system biases the sensor with a small, known DC current (chosen to minimize self-heating), and the instrument reads the resulting voltage drop (or a bridge output). Because resistance vs. temperature is well-characterized, that voltage change maps directly to oil temperature. This arrangement is robust, accurate, and well-suited to the harsh engine environment, making it a common choice for continuous, electrical power–fed measurements from the aircraft DC system.

Other sensor types either generate a signal without requiring a DC current to power the sensor element (thermocouples produce a voltage from temperature differences and need appropriate compensation), measure something other than the actual oil bulk temperature (infrared sensors read surface radiation and aren’t suitable for sealed oil in an engine), or rely on capacitance changes that typically use different excitation schemes (like AC) rather than a simple DC-powered resistance measurement.