They’re specified to switch at a given temperature set point, such as 30°C in the case of our example part. A common misconception with these devices is the notion that this switching temperature is the ambient temperature, or the system temperature. This is not the case.
Cantherm thermostats switch when the thermostat itself reaches its specified temperature, which can be long after the system they are controlling has met and exceeded the temperature set point. In temperature-sensitive systems which do not have time for the thermostat to heat up, you may want to consider using a thermostat with a lower switching temperature to offset this unavoidable delta between system temperature and thermostat temperature,