Relay hardware - Arc protection - Auto synchronization - Bay control and measurement - Merging unit - Transformer protection - 2 winding - Feeder protection - Voltage regulation - Capacitor bank protection - Petersen Coil control - Grid automation - Busbar differential protection (high impedance) - Back-up protection - Motor protection - Busbar protection (voltage and frequency) - Transformer protection - 3 winding - Interconnection protection - Generator protection - Power management/Load shedding - Operation Manual - REX640 Protection and control - Relion Protection and Control - PCL4 - IEC - ANSI - 16.02.2023

REX640 Operation Manual

The relay includes a Ready LED on the power supply module that indicates the relay's status. In normal situations, the Ready LED has a steady green light. Any other situation that requires the operator’s attention is indicated with a flashing light.

Figure 1. Hardware module slot overview of the REX640 relay
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Slot markings in enclosure (top and bottom)
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Ready LED

The relay has a nonvolatile memory which does not need any periodical maintenance. The nonvolatile memory stores all events, recordings and logs to a memory which retains data if the relay loses its auxiliary supply.