Thermoswitches, temperature switches, thermostats, and thermal protectors can generally be divided into two types: current and temperature.
Current: This type of device senses the current passing through the bimetal, and when the current exceeds the set temperature value, the bimetal will deform and trigger the switching action. This type of equipment is mainly used for overload protection and current control, and the impact on the current will be significant.
Temperature type: This type of equipment is adjusted and controlled according to the ambient temperature, the bimetal sheet is mainly affected by the temperature change, when the ambient temperature exceeds the set temperature value, the bimetal sheet will be deformed to trigger the switch action. This type of device has a relatively small impact on the current and is mainly affected by the temperature.
The thermal protector is small and airtight, and the bimetal sheet has a large resistance value, which will produce the thermal effect of the current when it passes through. This thermal effect increases the temperature of the thermal protector and thus its operating temperature.
Therefore, when choosing the operating temperature of the thermal protector, it is indeed necessary to consider the influence of the current factor. Specifically, if the required overload protection or temperature control function requires use at higher current levels, then a thermal protector with a higher operating temperature should be selected to ensure that the protection mechanism is not triggered prematurely during the normal operation of the device.
At the same time, it is also necessary to select the appropriate thermal protector model and specification according to the actual situation and application requirements, comprehensively consider the current, temperature, environmental conditions and other factors to ensure the safety and reliability of the equipment.
The thermal effect of the current does cause the temperature of the conductor to rise, and the role of a thermal protector is to cut off the current when the temperature of the conductor exceeds a certain value, so as to protect the device from the risk of overheating. When the current reaches 45% of the nominal current of the thermal protector, the heat generated by the current may cause the conductor temperature to rise, which in turn will affect the operation of the thermal protector.
In a closed environment, the ambient temperature rises as heat is not easily dissipated, resulting in an increase in the temperature around the thermal protector. In order to ensure that the operating temperature of the thermal protector is accurate and reliable, a common practice is to increase the operating temperature of the temperature control switch, temperature switch, and thermostat by 5-7 settings accordingly. By increasing the set temperature, the rise in ambient temperature can be compensated for to ensure that the thermal protector works properly within the correct temperature range.
It is important to note that the addition of 5-7 settings mentioned here is an empirical practice and may vary in specific applications. Different equipment and environmental conditions may need to be adjusted according to the actual situation. Therefore, in the specific engineering design, it is recommended to refer to the relevant standards, specifications and equipment manufacturers' recommendations to ensure that the operating temperature setting of the thermal protector is accurate and reliable.
For high-current thermal protectors (greater than 10A), if the overload capacity is not up to the requirements of the leads, the resistance of the leads will cause the leads to heat up, which will affect the operation of the thermal protector, temperature switch, temperature switch and thermostat. Therefore, it is necessary to ensure that the overload capacity of the lead wire meets the design requirements when selecting it to avoid unnecessary movements or failures.