The action temperature selection of a thermostat should be based on the application:
Measure the temperature of the position where the thermostat would be mounted;
Setting the temperature range of application;
Select the temperature of a thermostat.
The current flowing through thermostat need to be considered when selecting this temperature.
If this thermostat is used for heat protection, the action value should be above the normal working temperature, but lower than the temperature limit of other components to be damaged.