PCS-924 Stub Differential Relay

Model: PCS-924

In one-and-a-half breaker and ring breaker arrangements, the T-zone exists between two breakers and line/transformer feeders.


  • In one-and-a-half breaker and ring breaker arrangements, the T-zone exists between two breakers and line/transformer feeders. The PCS-924 is designed to provide current differential protection, sum-of-current protection and feeder end fault protection for the T-zone.
  • It provides three groups of CT input for direct connections to three terminal CTs. The disconnector is always installed in the feeder to facilitate the maintenance.
  • The relay considers the different operating scenarios for the feeder with the disconnector. 3-terminal and 2-terminal current differential protections are automatically enabled/ disabled to meet different scenarios with closed or opened disconnector. The feeder end fault protection is enabled when the disconnector is opened.
  • It is used to clear faults between CT and disconnector while keeping continuous operation of local breakers. The phase overcurrent protection employs the calculated sum current of two CTs. It can be applied for feeder energization and feeder backup protection.
  • The PCS-924 is compatible with IEC 61850 station bus and process bus applications. It supports IEC 61850-8-1 MMS, GOOSE and IEC 61850-9-2 Sampling Value. The RJ-45 faceplate port is provided for testing and setting, allowing for easier commissioning and maintenance.
  • Current differential protection (87S) The switchover of 3-terminal and 2-terminal current differential protection can be automatically implemented according to the open/close state of feeder disconnector. Two stage feeder end fault protection (50FLE)
  • This protection is only valid when the feeder disconnector is opened. It is used to clear the faults between CT and the opened disconnector.
  • It will send a transfer trip command to remote end and keep the local breakers in service. Sum overcurrent protection (50P) Phase overcurrent protection is based on the summed current of two CTs.
  • It can be used as the energizing protection or feeder backup protection.
  • Current drift auto adjustment The relay continually and automatically traces the voltage and current drifts and adjusts the zero point to acquire accurate measurements.

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