Question 205Electricity & Electronics - Assistant Engineer

The correct answer is D) self-powered thermocouples. A pyrometer is a type of temperature-measuring device that uses thermocouple technology to measure high temperatures, such as those found in diesel engine exhaust systems. Thermocouples are self-powered, meaning they generate a small electric voltage in response to temperature changes, rather than requiring an external power source like resistance temperature detectors (RTDs). The other options are incorrect because externally powered thermocouples (A) and externally powered RTDs (B) require a separate power source, while self-powered RTDs (C) do not use the thermocouple principle to generate the voltage signal for temperature measurement.