NT539 Temperature Controller

The NT539 temperature controller is designed for dry and cast resin transformers with more than 3 windings, commonly used for plant level DC/AC transformers, however it may also be used to monitor the temperature of medium and low voltage three phase transformers.  The NT539 is microprocessor based with 9 PT100 inputs and 3 relays for ALARM, 3 relays for TRIP, and 3 for the FAN cooling system.  Additionally it comes with a self monitoring circuit and output that will signal if it detects a sensor fault or other internal problem on the PC board.

On request a protective coating can be applied to the electronics board for tropical climates.


  • Temperature monitoring from 0°C to 200°C (32° – 392°F)
  • 24-240VAC input power
  • VDC with reversible polarities
  • Rated for use in ambient temperatures from -20° to +60°C (-4° to 140°F)
  • 9 inputs RTD Pt100 3 wires
  • All potential free output relays rated for up to 6A @ 250VAC
  • 3 alarm relays (Alarm)
  • 3 trip relays (TRIP)
  • 3 Fan relays
  • 1 alarm relay for sensor fault