The RJT-1 and RJT-3 relays are meant for use in the automation and protection circuits as a current monitoring elements with a programmable time delay and depth of hysteresis (absolute value of a difference between pickup and drop out current). The RJT-type relay has three isolated measuring inputs, and monitors up to three independent values of effective sinusoidal current 50Hz, with possibility to deactivate any of the inputs. The RJT-1 relay has one isolated measuring input, and monitors values of direct current by measuring drop of voltage on a measuring shunt. For each of the relays the following operating modes are available.

  • POD-PRD – operation after identifying decrease of monitored current below set value (Time-delay under-current protection),
  • NAD-NPRD – operation after identifying increase of monitored current over set value (Time-delay over-current protection),
  • KPW – operation when monitored current is within a set range (Time-delay within-range protection),
  • KPZ – operation when monitored current is beyond a set range (Time-delay out of-range protection).

For all of the given operating modes of the RJT-1 it is possible to choose operation with current direction control. Having input the transformiation ratio of current transformers into the RJT-3 relay, it is possible to preview values of primary currents.