Auxiliary, trip and supervision relays

1L710 700 Series Liquid Level Relay



The 1L710 Series relays are solid state liquid level detecting relays with electromechanical output contacts. Designed for application on auxiliary mains voltages the 1L710 provides an isolated low voltage to the liquid immersion probes. Due to the low voltage AC signals applied between electrodes, the effects of damaging electrolytic action is eliminated. The unit is ideally suited for measuring high and/or low levels of conductive liquids in storage tanks wherever high accuracy and reliable, maintenance free operation is essential.

The 700 Series range of electronic measuring relays are manufactured as a modular approach to electrical system protection & control. Designed to meet rigid Australian & international specifications the 700 Series provide a flexible, cost effective & extremely reliable solution for a multitude of applications under electrically hostile conditions.


The 1L710 monitors the resistance across two conductive probes to determine if there is liquid present between them. A HIGH & LOW PROBE plus common should be inserted as shown in the diagram. The sensitivity of the unit is set such that the relay will pick up when the fluid level falls below the end of the LOW probe. When this occurs the 1L710 automatically switches to monitor the HIGH probe and will cause the output relay to drop out when the liquid reaches this level. A typical application of the 1L710 would be to start a replenishing pump when a low liquid level is detected in the tank. The pump would be switched off when the high level probe was reached.


  • Ten year factory warranty
  • Plug in measuring module
  • Double insulated high impact polystyrol case
  • Termination socket included for surface mounting enabling front or rear connection with optional DIN rail mounting
  • Proven circuit designs based on over 15 years of field service in hundreds of varied & demanding applications
  • Easy to set calibration scales
  • Tolerance to shock & vibration for generator, compressor & mobile applications

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