What Is an Electronic Thermostat?
An electronic thermostat is a device that can control a load according to the measured temperature.
They are very reliable because they operate with high sensitivity and precision. Electronic thermostats are equipped with a thermistor for temperature measurement and a relay for load drive. A control circuit in the electronic thermostat measures the temperature and drives the load. By using a heater or cooler as the connected load, the temperature can be regulated, automating time-consuming temperature control and reducing electricity and other costs.
Uses of Electronic Thermostats
Electronic thermostats are used to control internal system temperatures by connecting heaters, coolers, and other heating and air conditioning equipment because they can turn connected loads on and off based on the detected temperature.
This allows for 24-hour monitoring and control while maintaining the set temperature, thus reducing power costs.
They are used in a wide range of environments where temperature control is required, such as in the fields of agriculture and air conditioning.
Principle of Electronic Thermostats
The electronic thermostat consists of a thermistor, relay, and control circuit.
The control circuit and thermistor measure the current temperature, and the control circuit and relay turn the load connected to the electronic thermostat on and off. The thermistor is an electronic component with a characteristic of resistance value changing with temperature change. The control circuit uses this relationship between temperature and resistance to measure temperature.
A relay is an electronic component formed by a coil and a switch. The magnetic force generated by passing current through the coil is used to switch the switch.
The control circuit turns the current in the coil in the relay ON/OFF by comparing the temperature measured using a thermistor with a preset temperature. The switch in the relay is turned on and off when the coil current is turned on and off. By connecting a load to the relay switch side of the electronic thermostat, it is possible to control ON/OFF according to the temperature.
How to Select an Electronic Thermostat
The points to consider when selecting an electronic thermostat are as follows.
1. Contact Capacity
The contact capacity is the current consumption of the load that the electronic thermostat can drive. The contact capacity varies from electronic thermostat to electronic thermostat, and the value depends on the relay in the electronic thermostat. The electronic thermostat should be selected so that the current consumption of the load to be controlled ON/OFF is not higher than the contact capacity rating of the electronic thermostat. The relay in the electronic thermostat may break down if the ON/OFF load exceeds the contact capacity of the electronic thermostat.
2. Measuring Range Temperature
The temperature range that can be measured differs depending on the electronic thermostat. The measuring temperature range depends on the thermistor in the electronic thermostat. The electronic thermostat should be selected according to the temperature range to be measured. Some electronic thermostats have interchangeable thermistors.
3. Load Actuation Pattern
Electronic thermostats have two load operating patterns: heating control pattern and cooling control pattern. In the heating control pattern, the load can be turned ON when the current temperature is lower than the set temperature. The cooling control pattern turns the load ON when the current temperature is higher than the set temperature. Some electronic thermostats can switch the load operation pattern with a switch.
4. Operating Temperature Indication Method
There are two methods for setting the temperature at which the load connected to the electronic thermostat is turned on or off: analog setting method and digital setting method.
In the analog setting method, the operating temperature is set by turning the jog dial on the electronic thermostat. In the digital setting method, the operating temperature is set while viewing the electronic thermostat’s display. The digital setting method is easier to use but costs more than the analog setting method.