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  • PCS-921 Breaker Failure Relay

  • The PCS-921 numerical relay provides protection for circuit breakers, which includes breaker failure protection, pole discrepancy protection, dead zone protection, phase/ negative sequence overcurrent protection, earth-fault protection, overvoltage protection, undervoltage protection, frequency protection, single and/or three-pole auto-reclosing and synchronism check functions. The PCS-921 relay employs the programmable logic, configurable I/Os and definable 3-color LEDs to provide flexibility for specific applications. Frequency tracking is used to minimize the sampling error caused by system frequency fluctuation. The PCS-921 relay adopts the advanced multi-processor platform, providing the interfaces to station bus and process bus respectively and supporting IEC 61850-8-1 MMS, GOOSE and IEC 61850-9-2 Sampling Value. In addition, the RJ-45 faceplate port serves for testing and setting in effort to make commissioning and maintenance easier.

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Protection and Control
  • Breaker failure protection (50BF)
  • Pole discrepancy protection (62PD)
  • Dead zone protection (50DZ)
  • Four stages of phase overcurrent protection (50/51P)
  • Four stages of neutral overcurrent protection (50/51G)
  • Four-stage negative sequence overcurrent protection (50/51Q)
  • Three-stage undervoltage protection and overvoltage protection (27/59)
  • One-stage negative sequence overvoltage protection (59Q)
  • Four-stage underfrequency protection and overfrequency protection (81)
  • Synchronism check (25)
  • Single and/or three-pole auto-reclosing (79)
  • Voltage and current drift auto adjustment
  • Frequency tracking

Monitoring and Measurement
  • VT circuit supervision (VTS)
  • CT circuit supervision (CTS)
  • Self diagnostic
  • Event recorder including 1024 disturbance records, 1024 binary events, 1024 supervision events and 1024 operating logs
  • Disturbance recorder including 32 disturbance records with waveforms (The file format of disturbance recorder is compatible with international COMTRADE file.)
  • Clock synchronization using IRIG-B, SNTP, PPS (Pulse-Per- Second) and PPM (Pulse-Per-Minute)

  • Up to four 10Base-T/100Base-TX copper Ethernet ports using IEC 61850, DNP3.0 or IEC 60870-5-103 over TCP/IP
  • Up to two 100Base-FX optical Ethernet ports using IEC 61850, DNP3.0 or IEC 60870-5-103 over TCP/IP (Sharing two copper Ethernet ports)
  • Two RS-485 serial ports using IEC 60870-5-103
  • One RS-485 serial port for clock synchronization
  • Optional Sampling value and GOOSE communication module with six/eight optical Ethernet ports using IEC 61850- 9-2 and IEC 61850-8-1 GOOSE

User Interface
  • HMI interface with large-size LCD and 9-button keypad on the front panel
  • One front RJ-45 port for testing and setting
  • One RS-232 or RS-485 rear port for printer
  • Language selection – English + selected language
  • Assistant software - PCS-Explorer

  • A unique two-out-two logic is adopted in hardware design to improve security. Coordinating with the redundant scheme, this solution improves both security and dependability of protection system. The two independent data acquisition paths are provided to prevent mal-operation caused by component failure. One works as a fault detector and the other is designed for protection logic. Tripping outputs are supervised by both data acquisition paths.
  • Comprehensive flexibility is provided via the modular hardware design, scalable function library, programmable logics, configurable I/Os and definable LEDs. This allows users to create customized schemes for specific projects. Two fixed LEDs and 18 definable 3-color LEDs (Green/ Yellow/Red) are provided.
  • The relay is designed based on NR Electric’s well-established and proven hardware platform with multi- processor architecture. The multi-CPU technology supports parallel operation of CPU modules.
  • The relay is fully compatible with IEC 61850, it includes station bus communication and process bus communication. The relay provides up to 6 Ethernet ports for process bus with IEC 61850-9-2 Sampling Value and IEC 61850-8-1 GOOSE, as well as up to 4 Ethernet ports for station bus with IEC 61850-8-1 MMS.