Measurement Specialties' PTC Motor Protection Sensors are designed to provide economic and reliable overtemperature protection for three-phase motors. This assembly utilizes a small PTC disk that has a low base resistance. Once the motor winding temperature reaches the trip temperature of the PTC thermistor, its resistance increases several orders of magnitude for a small increase in temperature. This sharp increase in resistance is easily recognized buy the motor protection module or other electronics and can be used to shut down the system before any damage occurs.
Because the PTC assemblies are very small and rugged, they can be located in compact locations where protection is needed, such as directly inside the motor windings and can withstand standard varnish dip and bake operations and other handling.
A number of sensors can be connected in series to cover a larger area. If any of the assemblies see an overtemperature condition, it will increase in resistance and indicate a fault condition.
PTC Motor Protection Sensor Datasheet (142K)
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