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Connection circuit diagram |
Characteristic |
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The temperature sensor is a positive temperature coefficient thermistor (PTC) which offers comprehensive protection against thermal motor overload. The temperature of the winding can be accurately monitored thanks to its low thermal capacity and the excellent thermal contact with the winding. The PTC thermistor exhibits a sudden change in resistance when its rated response temperature is reached.
A tripping unit is used to evaluate the change in resistance and open auxiliary circuits via auxiliary contacts.
The switching hysteresis of the PTC thermistor is low, which facilitates fast restarting of the drive. Motors with this type of protection are recommended for heavy duty starting, intermittent duty, extreme changes in load, high ambient temperatures, or fluctuating supply systems.
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See also "Motor protection"
