Ingersoll-Rand Xe-145M, Pocket Manual

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P6 Analog Temp Sensor Inputs
Temperature sensitive resistors called, thermistors, are
used to monitor temperature changes at various points
within the compressor package. They operate on a 5
volt DC circuit.
How a thermistor work?
As the temperature of the sensor changes the
resistance through the sensor changes by a
corresponding amount. As the output voltage varies
due to the temperature changes, the voltage signal is
processed by an analog to digital converter within the
controller. The Xe controller uses Negative
Temperature Coefficient (NTC) thermistors, meaning
that temperature and resistance are inversely
proportional. In other words, as temperature increases,
resistance decreases and vice-versa. The controller
may provide a warning of rising temperature or could
shut the compressor down if operating conditions
dictate.