Thermostat is devided into mechanical and electronic type, Mechanical type is using two different thermal expansion coefficients of metal pressed together, the temperature change, he will change the curvature when bent to a certain degree, is turned on (or off) the circuit, so that the cooling (or heating) equipment jobs. Electronic type is thermocouple, platinum resistance temperature sensing devices, etc., the temperature signal is converted into an electrical signal by the microcontroller, PLC and other circuit control relay so that the heating (or cooling) the device to work (or stop). There mercury thermometer type, temperature will have to contact and mercury ON.
Divided by Manufacturing principles,the thermostat is divided into: A sudden jump thermostat: a variety of sudden jump thermostat models collectively KSD, such as the common KSD301, KSD302, etc., the thermostat is bimetallic thermostat of new products, primarily as a variety of electric When a thermal protection product, usually used in series with a thermal fuse, the sudden jump thermostat as primary protection. Thermal fuse in the sudden jump thermostat Lou loss or failure causes a heating element over temperature, as a secondary protection since, effectively prevent burn out the heating element and the consequent fire. Second, the liquid up thermostat: to make material thermostat temperature portion of the object to be controlled when the temperature changes (usually liquid) to produce the corresponding thermal expansion and contraction of the physical phenomena (volume change), and a sense of Temperature bellows portion communicating together produce expansion or contraction. With leverage, driven by switching-off operation, to achieve the purpose of constant temperature liquid expansion type thermostat with temperature control accurate, reliable, small-OFF temperature, temperature control large adjustment range, and large overload current performance characteristics. Liquid up thermostat is mainly used for household appliances, electric equipment, refrigeration industries with temperature control applications. Third, the pressure thermostat, change the thermostat filled by the sealing temperature of the working fluid temperature and capillary, the alleged change in temperature or pressure change into a space volume, to a temperature set point, by elastic element and fast transient mechanism, automatically closes the contact, in order to achieve automatic control of temperature. It sets the body part by the temperature unit, temperature, perform the opening and closing of the micro-switch or automatic damper composed of three parts. Pressure type thermostat is suitable for refrigeration appliances (such as refrigerators freezers, etc.) and heating and other occasions. Fourth, electronic thermostat, electronic temperature controller (resistance) is the use of resistance temperature sensing methods to measure, the general platinum wire, copper, tungsten, etc., as well as thermistor temperature resistance, these resistors each has its advantages indeed point. Most home air conditioners generally use thermistor.