1, the working principle
Its working principle is through the temperature sensor to automatically check the ambient temperature, real-time monitoring, when the ambient temperature is higher than the control set value when the control circuit starts, you can set the control hysteresis. If the temperature is still rising, when rising to the set limit alarm temperature point, start the alarm function. When the controlled temperature can not be effectively controlled, in order to prevent the destruction of equipment can also be through the trip function to stop the device to continue running. Mainly used in the power sector to use a variety of high and low voltage switchgear, dry-type transformers, box-type substation and other related temperature use.
2, buy thermostat precautions
(1) thermostat input, output voltage selection
First of all to ensure that the input voltage in line with the actual situation, there is no excessive demand for AC power supply, mainly with DC power supply must pay attention to positive and negative wiring is correct, can not be reversed, otherwise it will burn out the thermostat. So we recommend the use of AC power supply thermostat. It is also worth noting that some of the thermostat does not support the DC off, or can be off the DC voltage is small, the purchase of the thermostat when the business must be clear with the consultation, so as to avoid unnecessary trouble The
(2) thermostat output control power
Thermostat output control power is the first choice to choose the thermostat problem, which relates to the use of security and stability, if improper choice may cause a fire. Thermostat are marked with the output control voltage and current, the output control voltage and current multiplication can be output control power. The operating power of the controlled device must be less than the output control power of the thermostat. Otherwise there is the possibility of security risks.
Example: Thermostat marked 220V, 10A, the thermostat output control power of 2200W, under normal circumstances, the equipment should be controlled power should not be greater than 2000W.
Warm Tip: the general control of the power of the device should not be greater than the thermostat output control power of 90%, leaving 10% of the margin can ensure the stable operation of the thermostat.
3, how to examine the quality of a thermostat
(1) to see the thermostat selected output control core – relay. Relay as the core components of the output control, its performance determines the stability of the quality of the temperature controller is good or bad. The choice of the relay brand to a large extent affect the manufacturing cost of the thermostat, so the general manufacturers are mainly used in domestic relays, such as loose music, Hongfa. Better manufacturers choose Taiwan’s relays, such as Matsukawa. Good manufacturers choose to import well-known brands of relays, such as Omron, Panasonic. Different grades of relay quality gap is great, the price gap is also great. So only a good manufacturer will use Omron, Panasonic and other big brands of relays, to ensure that their products of good products
quality. Customers can choose this as a reference factor when choosing a thermostat.
(2) thermostat CPU is the thermostat of the brain, it is good or bad affect the accuracy of the thermostat, stability and so on. There are two main types of data acquisition core present on the market: one is the core of the combination of microcontrollers and ADC chips, and the other is a powerful CPU integrated ADC acquisition core. In general
, The integration of the core stability is better, because the links are more prone to problems. At present the market also appeared in some businesses in order to attract customers, the microcontroller and ADC said “dual-core”, because from the appearance of look like. This is purely Huyou customers, please customers should pay attention to this point friends. Currently on the market of the thermostat ADC mainly to 10, 12-bit, high-end use of 14 or 16-bit. The higher the number of bits, the smaller the temperature change can be resolved, that is, higher precision, so buy a thermostat to try to buy a high number of ADC thermostat.
(3) the manufacturer’s software programming is also an aspect of the accuracy of the thermostat. General thermostat temperature sensors are NTC temperature sensor, its resistance with the temperature curve is not linear, in different temperature range, the slope of the curve is different. So when the manufacturers should be programmed according to this feature, the program is divided into multiple sections so that the display temperature and the actual temperature closer. But the program is the customer can not see things, the general business will not take the initiative to tell the customer, so pay attention to this more difficult to achieve.
(4) to see the thermostat power supply. There are two main types of thermostat power supply on the market: switching power supply, transformer power supply. Switching power supply because it is high-frequency power supply, the power part of the higher requirements, it is prone to EMI interference, affecting the stability of the thermostat. General customers do not know the power supply part of the thermostat is good or bad, it is recommended to use the transformer power supply thermostat. Transformers are divided into two kinds, one is more common open-type transformers, the other is potting transformer, that is, there is a plastic shell. Potting transformer has a good moisture resistance, the effect of electrical isolation is also better, it is recommended to use the use of potting transformer power supply thermostat.
(5) try to buy digital thermostat. There are two main forms of temperature control on the market: mechanical, electronic. Electronic thermostat with user interface user-friendly, intuitive and simple operation, so the purchase of thermostat should try to use electronic.
4, thermostat accuracy requirements
The optional thermostat must also take into account the accuracy requirements of the thermostat. For example, we need to control the temperature accuracy of 0.1 degrees, and some thermostat accuracy of 1 degree, which does not meet the practical application requirements.
How to choose a Temperature controller
1, the working principle