Lab Thermal Resistance Sensing Core Working Principle
Oct 16, 2025
The core of the thermal resistance induction in high and low temperature test chambers also utilizes the physical property that the resistance value of platinum metal changes with temperature. The core logic of the control system is a closed-loop feedback control: measurement → comparison → regulation → stability
Firstly, the thermal resistance sensor senses the current temperature inside the chamber and converts it into a resistance value. The measurement circuit then converts the resistance value into a temperature signal and transmits it to the controller of the test chamber. The controller compares this measured temperature with the target temperature set by the user and calculates the deviation value. Subsequently, the controller outputs instructions to the actuator (such as the heater, compressor, liquid nitrogen valve, etc.) based on the magnitude and direction of the deviation. If the measured temperature is lower than the target temperature, start the heater to heat up; otherwise, start the refrigeration system to cool down. Through such continuous measurement, comparison and adjustment, the temperature inside the box is eventually stabilized at the target temperature set by the user and the required accuracy is maintained.
Due to the fact that high and low temperature test chambers need to simulate extreme and rapidly changing temperature environments (such as cycles from -70°C to +150°C), the requirements for thermal resistance sensors are much higher than those for ordinary industrial temperature measurement.
Meanwhile, there is usually more than one sensor inside the high and low temperature test chamber.
The main control sensor is usually installed in the working space of the test chamber, close to the air outlet or at a representative position. It is the core of temperature control. The controller decides on heating or cooling based on its readings to ensure that the temperature in the working area meets the requirements of the test program.
The monitoring sensors may be installed at other positions inside the box to verify with the main control sensors, thereby enhancing the reliability of the system.
Over-temperature protection is independent of the main control system. When the main control system fails and the temperature exceeds the safety upper limit (or lower limit), the monitoring sensor will trigger an independent over-temperature protection circuit, immediately cutting off the heating (or cooling) power supply to protect the test samples and equipment safety. This is a crucial safety function.
Lab thermal resistance sensor is a precision component that integrates high-precision measurement, robust packaging, and system safety monitoring. It serves as the foundation and "sensory organ" for the entire test chamber to achieve precise and reliable temperature field control.
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