1. Application background

Heating belt system is widely used in the science and technology industry, such as soft heating cloth bag needs to be used to maintain the temperature of vacuum tubes and gas pipelines used in various science and technology industries.  Once  the heating is out of control,  the heating belt needs  to start the  overtemperature protection function and cut off the heating power supply when it is heating up. Therefore, as a key device of overtemperature protection, the  temperature switch plays a vital role in the heating belt system.

2. protection principle

The temperature switch is a mechanical passive component, which is often set in the main circuit in the heating belt system. When the circuit failure or current exceeds the rated value, the circuit abnormal heating causes the temperature to rise, the temperature switch through the internal heat sensitive element bimetallic induction of external temperature changes, once the temperature exceeds the set threshold, the double deformation, disconnect the contact, cut off the circuit, thus playing a whole machine protection.

When the heat sensitive element operates, the contact is disconnected, and the contact resistance changes instantaneously from within 50ma to close to infinity, shutting off the main circuit current, thus playing a role in protecting the whole machine.

When the ambient temperature is reduced to the reset temperature of the temperature switch, the heat sensitive element returns to the initial state, the contact is closed again, and the resistance value signal is given to the circuit within 50ma. The actuator then operates according to the program setting.

3. The installation position

The temperature switch is installed in the heating layer of the heating belt system, and is often placed close to the heating line laying position or can feel the heating temperature quickly, so as to monitor temperature changes in time.

4. Selection factors

• Rated current and voltage: Ensure that the rated current and voltage of the selected temperature switch meet the operating current and voltage requirements of the heating belt to ensure normal operation.

• Protection temperature: Choose different temperatures according to the design and installation position, usually choose 120℃, 150℃, 200 ℃, these three temperature grades.

• Contact switch form: divided into normally closed, normally open two, normally closed for the initial state of contact closed, to the protection temperature contact disconnected. Normally open is just the opposite. Choose different switch forms according to the design.

• Size and installation mode: Select the appropriate size and installation mode of the thermal protector according to the size and installation space of the heating belt to ensure that the installation is convenient and does not affect the normal operation of the equipment.