How does the temperature sensor PTC of the EC 60 work?
The used PTC (Positive Temperature Coefficient) thermistor is a resistor which depends on temperature in a nonlinear way. As soon as the temperature exceeds a certain value the resistance increase is very steep. Hence a PTC can be used to monitor the temperature.
In the EC 60 the PTC is glued onto the winding and measures the winding temperature. If a typical value is exceeded (about 115°C) the resistance of the PTC increases strongly. This increase in resistance can be used in an electronic circuit e.g. to switch off the motor current to protect the motor from overheating.