RCS-921 Breaker Failure Protection

The RCS-921 relay is a breaker failure relay with automatic reclosing used for the protection of circuit breakers in all kinds of busbar arrangement. It integrates breaker failure protection, overcurrent protection, pole discrepancy protection and......

  • Overview
  • Functions
  • Features

The RCS-921 relay is a breaker failure relay with automatic reclosing used for the protection of circuit breakers in all kinds of busbar arrangement. It integrates breaker failure protection, overcurrent protection, pole discrepancy protection and automatic reclosing function.

  • Breaker failure protection (50)
  • Pole discrepancy protection (52)
  • Two stages overcurrent protection (67P)
  • Two stages zero-sequence overcurrent protection (67G)
  • Automatic reclosure (AR) function (79)
  • Synchronism check (25)
  • Frequency tracking
  • VT circuit supervision
  • CT circuit supervision
  • Self diagnostic
  • DC power supply supervision
  • Event recorder, including 256 binary input change reports, 256 self-supervision reports and 256 control reports.
  • Disturbance recorder, including 256 fault reports and 6 fault waveforms
  • GPS clock synchronization – PPS (pulse per second), PPM (pulse per minute) and IRIG-B signal
  • 2 RS-485 communication rear ports conform to IEC 60870- 5-103 protocol
  • 1 RS-485 communication rear ports for clock synchronization
  • 2 or 4 optional Ethernet ports, IEC 61850, or IEC 60870-5- 103 over TCP/IP
  • 1 RS-232 communication faceplate port for testing and setting
  • 1 RS-232 communication rear ports for printer

  • High-performance hardware platform and modularized design(MCU+DSP). MCU manages general fault detector element and DSP manages protection and metering. The data acquisition system is completely independent of electronic circuit. The DC power supply of output relay is switched on only if the general fault detector element operates so as to avoid maloperation resulting from damage of any apparatus.
  • Up to 0.01Hz accurate frequency metering, wide range of frequency tracing. Frequency can be accurately traced within the range of 40Hz~65Hz.
  • The self-adaptive floating threshold only reflects the deviation of power frequency component, thus is immune to system imbalance and system disturbance.
  • 24 samples per cycle, all task including data measurement, protection calculation, logic discrimination, event recording and protection logic calculation can be completed within one sampling period.
  • Flexible automatic reclosure mode supporting multiple initiation mode and check mode.
  • Overcurrent protection is provided in the relay for energizing a faulty bus or energizing a faulty line.
  • The connector type can be selected as plug in/out terminal connector or crimp terminal connector. The unique plug in/ out terminal connectors from the relay rear panel to the terminal blocks on the rack or cabinet makes the on-site commissioning and replacement much easier than the traditional screw terminals when you do the commissioning.