The snap-action thermostat, also known as a temperature switch and thermal protector, can be divided into two types: current type and temperature type. It is usually small in size and enclosed, due to the relatively high resistance of the bimetallic strip.

In the current type snap-action thermostat, there is a current thermal effect when current passes through it, which means that the action temperature is greatly influenced by the current. When selecting the action temperature of the snap-action thermostat, the influence of the current factor must be considered.

Firstly, when the current reaches 40% of the rated current of the snap-action thermostat, the influence of the current thermal effect on the thermostat becomes significant. In a sealed environment, the action temperature should be increased by 5℃; in an open environment, the action temperature should be increased by 8℃.

Secondly, when the action temperature of the snap-action thermostat is below 70℃, the influence of the current thermal effect on its action also becomes apparent.

For the temperature type thermostat, since the current does not pass through the bimetallic strip, the influence of the current thermal effect on its action is relatively small. However, for high-current thermostats (greater than 10A), if lead wires with inadequate overload capacity are chosen, it may cause the thermostat to act prematurely.