Thermal Principles of Thermorresistors

Thermoresistors consist of temperature sensors with operating principle based on a property that some components that can vary the electrical resistance with change of temperature. These sensors have a calibrated resistance that can vary linearly according to their temperature, allowing continuous monitoring of the motor heating process by a controller display, with a high degree of sensitivity and return accuracy. The two-wire configuration is often satisfactory in environments where the length of the sensor cable to the instrument does not exceed 3m for 20 AWG gauge.

In the configuration of three wires, the most used by industries, there is a compensation of the electrical resistance by the third wire. In the four-wire configuration, which requires a more precise assembly, there are two connections for each terminal of the bulb, two wires for voltage and two for current, thus obtaining a total balance of resistances, usually used in cases where High precision is required. This same sensor can also operate as an alarm for operations that occur above the common working temperature.