Smart Touch Temperature control switch ——— Thermostat

Synonyms Temperature control switch generally refers to thermostat

Thermostat refers to a series of automatic control components that produce some special effects and produce turn-on or turn-off actions according to the physical deformation inside the switch according to the temperature change of the working environment. It is also called temperature control switch and temperature protector. , Temperature controller, referred to as thermostat. Or the temperature is transmitted to the temperature controller through the temperature protector, and the temperature controller issues a switch command to control the operation of the equipment to achieve the desired temperature and energy saving effect.

The application range of thermostats is very wide. According to different types of thermostats, they are used in many products such as household appliances, motors, refrigeration or heating.

working principle

Its working principle is to automatically sample and monitor the ambient temperature through the temperature sensor. When the ambient temperature is higher than the control set value, the control circuit starts, and the control hysteresis can be set. If the temperature is still rising, when it reaches the set over-limit alarm temperature point, the over-limit alarm function will be activated. When the controlled temperature cannot be effectively controlled, in order to prevent the destruction of the equipment, the tripping function can also be used to stop the equipment from continuing to operate. Mainly used in various high and low voltage switch cabinets, dry-type transformers, box-type substations and other related temperature applications used in the power sector.

Wiring method

Look carefully at the three feet on the thermostat. They are all replaced by English letters and numbers, which are H (6), L (3), and C (4).

H(6) is connected to the brown wire, which is the live wire of the power supply;

L(3) is connected to the gray wire, which is the live wire of the lamp;

C(4) is connected to the white wire, which is the hot wire of the compressor.

Control Method

There are generally two control methods; one is controlled by the temperature change of the object to be cooled, mostly using a vapor pressure temperature controller, and the other is controlled by the temperature difference of the object being cooled, mostly using electronic temperature Controller.

It adopts fuzzy control technology such as PID control, P (Proportional) proportional + I (Integral) integral + D (Differential) differential control.

Sudden jump thermostat


The bimetallic snap-type thermostat is a kind of bimetallic strip after a fixed temperature as a heat-sensitive reaction component. When the temperature of the main part of the product rises, the heat generated is transferred to the bimetallic disc and reaches the action temperature setting. Quick action, the function of the mechanism is to open or close the contact; when the temperature drops to the reset temperature setting, the bimetallic strip quickly returns to its original state, making the contact close or open, achieving the purpose of connecting or disconnecting the circuit, thereby Control circuit.

The models of various sudden jump thermostats are collectively referred to as KSD, such as KSD301, KSD302, etc. The thermostat is a new type of bimetallic thermostat. It is mainly used for various electric heating products with overheat protection. The fuse is connected in series, and the sudden jump thermostat is used as the primary protection. The thermal fuse acts as a secondary protection when the sudden jump thermostat fails or fails to cause the heating element to overheat, effectively preventing the burning of the heating element and the resulting fire accident.

Liquid expansion thermostat


It is a physical phenomenon (volume change) that causes the substance (usually liquid) in the temperature sensing part of the thermostat to expand and contract when the temperature of the controlled object changes, and the bellows connected with the temperature sensing part expands Or shrink. Based on the principle of lever, the switch can be turned on and off to achieve the purpose of constant temperature. The liquid-expandable thermostat has the performance characteristics of accurate temperature control, stability and reliability, small temperature difference between on and off, large temperature control adjustment range, and large overload current. Liquid expansion thermostats are mainly used in temperature control occasions such as household appliances industry, electric heating equipment, refrigeration industry and so on.

Pressure thermostat


The thermostat converts the change of the controlled temperature into a change of the space pressure or volume through a closed temperature bulb and capillary filled with a temperature-sensitive working fluid. When the temperature setting value is reached, through the elastic element and the fast transient mechanism, The contacts are automatically closed to achieve the purpose of automatic temperature control. It is composed of a temperature sensing part, a temperature setting main body, a micro switch or an automatic damper for opening and closing. Pressure thermostats are suitable for refrigeration appliances (such as refrigerators and freezers, etc.) and heaters.

Electronic thermostat


The electronic temperature controller (resistance type) is measured by resistance temperature sensing method. Generally, platinum wire, copper wire, tungsten wire and thermistor are used as temperature measuring resistors. Each of these resistors has its own advantages. General household air conditioners mostly use thermistor type. Electronic temperature controllers have the advantages of stability and small size, and are used in more and more fields.

Digital thermostat


Digital electronic temperature controller is an accurate temperature detection controller,

Thermostat (Picture 8)

The temperature can be digitally controlled. Thermostats generally use NTC thermal sensors or thermocouples as temperature detection elements. Its principle is: the NTC thermal sensors or thermocouples are designed into the corresponding circuits. The NTC thermal sensors or thermocouples change with the temperature. Corresponding voltage and current changes will be generated, and then the changed voltage and current will be detected and quantified by the microcontroller, and corresponding control will be done. The digital temperature controller has the characteristics of high accuracy, good sensitivity, intuitiveness and convenient operation.

main effect

In most cases in Europe, the thermostat is a necessary accessory for the wall-hung boiler, and the two are delivered to the user at the same time, and most of the thermostats equipped are smart thermostats. In China, nearly 95% of wall-hung boilers that have been installed in operation and are being installed and debugged and are ready to be put into use are not equipped with any form of simple or intelligent thermostat in advance. The room heating system equipped with thermostats, especially smart thermostats, is an extremely prominent and most important link in the comprehensive energy-saving heating system.

Convenience: Automatically adjust the wall-hung boiler in advance or delay every day, eliminating manual operation, which is most necessary for office workers’ families;

Comfortable: The room temperature is automatically adjusted at each time of day, morning, night and night, eliminating the embarrassment of getting up in the morning and waiting for the room to heat up after returning home from get off work.

Gas-saving: the extensive water temperature control is changed to advanced and accurate room temperature control, and the room temperature is set at different intervals to run on demand, without the need for open day and night gas heating;

Don’t worry: when the room temperature is too low, the wall-hung boiler is forced to start, and the room can be safely protected against freezing with very little gas.

Service life

Thermostats are widely used in various home appliances, such as refrigerators, water dispensers, water heaters, coffee makers, etc. The quality of the thermostat directly affects the safety, performance and life of the whole machine, and is a very critical component. Among the many technical indicators of thermostats, life is one of the most important technical indicators to measure thermostat products. The home appliance standard stipulates that the life of the thermostat is at least 10,000 times. Some home appliances, such as the thermostat that controls the motor-compressor in refrigerator products, and some thermostats in the liquid-filled radiator require at least 100,000 times.