Since the current flowing through the bimetal of thermal switch would generate heat, the action temperature selection should consider the working current.
In our factory, we normally use a testing curve to identify the suitable temperature. The following curve is only an example for 17AME series thermal switch.
Because every thermal switch could use bimetal with different resistance, the curve would be different also.
For example, if you want to control the temperature of your application to be 85C, and the current is 10A, the actual action temperature of thermal switch under no load should be 130C, the correct model is 17AME033A5. It is only an example and different thermal switch models would have different curves. The end users only need to tell us the exact temperature of your application to be controlled. We can help you to select the correct temperature and model.