PCS-924 Stub Differential Relay

The PCS-924 numerical relay provides current differential protection, sum overcurrent protection and feeder end fault protection for the T-zone in breaker-and-a-half arrangement and ring breaker arrangement. It integrates the three groups of CT......

  • Overview
  • Functions
  • Features

The PCS-924 numerical relay provides current differential protection, sum overcurrent protection and feeder end fault protection for the T-zone in breaker-and-a-half arrangement and ring breaker arrangement. It integrates the three groups of CT input and provides both 3-terminal and 2-terminal current differential protections for T-zone according to the binary input of feeder breaker auxiliary contact. The feeder end fault protection based on the feeder CT is adopted to avoid the trip of local breakers and send transfer trip command to the remote end when the feeder isolator is open. In addition, the overcurrent protection based on the sum of two breaker CTs is used as the feeder backup protection or energizing protection.

The PCS-924 relay employs the programmable logic, configurable I/O and definable 3-color LEDs to provide the flexibility for the specific application.Frequency tracking is used to minimize the sampling error due to system frequency fluctuation. The PCS-924 relay adopts the advanced UAPC multi-processor platform which is fully complied with IEC 61850. It provides the interfaces for station bus and process bus respectively and supports IEC 61850-8-1 MMS, GOOSE, IEC 61850-9-2 Sampling Value. And it provides the RJ-45 faceplate port for testing and setting to make commissioning and maintenance easier.

Protection and Control
  • Current differential protection (87S)
    3-terminal and 2-terminal current differential protection can be automatically switched according to the binary input of feeder isolator status. If the feeder is open by the isolator, the feeder CT will automatically quit from the current differential protection.
  • Feeder end fault protection (50FLE)
    This element will be valid when the feeder isolator is open. Due to the fault between isolator and feeder CT, the fault current only flows through the feeder CT and no fault current passes the two breaker CTs. Thus the relay will send the transfer trip command to the remote end and keep the local breakers closed.
  • Sum overcurrent protection (50P)
    The overcurrent protection adopts the sum of phase currents from two breaker CTs. It can be used as the energizing protection or feeder backup protection.
  • Current drift auto adjustment
    The relay continually and automatically traces the current drifts and adjusts the zero point.
  • Frequency tracking
    Frequency tracking is provided to accommodate the frequency shift in power system.

Monitoring and Measurement
  • CT circuit supervision (CTS)
  • Self diagnostic.
  • Auxiliary power supervision
  • Event recorder including 1024 disturbance records, 1024 binary events, 1024 supervision events and 1024 operating logs.
  • Disturbance recorder including 64 disturbance records with waveforms (The file format of disturbance recorder is compatible with international COMTRADE file.).
  • Counter of circuit breaker operation (single-pole tripping, three-pole tripping and reclosing).

Communication
  • Two 10Base-T/100Base-TX (RJ45) ports and two optional 100Base-FX ports with IEC 61850-8-1 MMS and GOOSE for non-time-critical message, IEC 60870-5-103 over TCP/IP or DNP 3.0
  • Two RS-485 rear ports with IEC 60870-5-103
  • Six or Eight 100Base-FX ports with IEC 61850-9-2 Sampling Value and GOOSE for time-critical message
  • One RS-485 rear port for clock synchronization
  • One RS-232 rear port for printer
  • One faceplate RJ45 port for testing and setting
  • Clock synchronization via Pulse-Per-Second, IRIG-B and SNTP

  • The relay is designed based on NR’s well established and proven UAPC hardware platform with multi-processor architecture. The multi CPU technology supports parallel operating simultaneously.
  • The two independent data acquisition paths can prevent any undesired trip caused by component failure. One works as a fault detector and the other is designed for protection and its logic. Tripping outputs are supervised by the fault detector to prevent a mal-operation.
  • The fault detector element consists of the pickup of differential current and the pickup of the sum current from two breaker CTs.
  • The differential current is monitored continuously. If the differential current exists for a long time, an alarm will be issued to awake the operators.
  • The connector type is optional, one is the plug in/out terminal connector and the other is the screw terminal connector. The unique plug in/out terminal connectors are used to connect the rear panel to the terminal blocks on the rack or cabinet, making on-site commissioning and replacement much easier than using traditional screw terminals.
  • The relay is compatible with IEC 61850-8-1 MMS, GOOSE and IEC 61850-9-2 Sampling Value and provides the independent interfaces for station bus and process bus respectively.