The Thermistor Trip Relay , when used in conjunction with positive temperature co-efficient thermistors, will help protect against
  • Sustained overload
  • Single phasing
  • Locked rotor
  • Blocked ventilation
  • High ambient temperature
  • LED trip indication
  • 2 pole relay contacts
  • Energize/De-energize function swapping
  • Auto / Manual Reset
Priciple of operation
The protector comprises a voltage level detector which detects the voltage across the thermistor. At normal temperature, when the thermistor resistance is low, a command signal energises a change - over relay and a green LED showing ‘safe’ condition.
At a pre - determined temperature, the thermistor resistance increases rapidly, which de - energises the relay. The actual trip temperature is governed by the thermistor characteristic, which can be obtained from the manufactuer’s data.
Failure of the supply to the unit or open circuit in thermistor winding will cause the relay to de-energise, thereby providing a failsafe facility.