RCS-985TS Transformer Protection

The RCS-985TS provides transformer protection for twowinding and three-winding main transformers, auxiliary transformers and startup/standby transformers in power plants with voltage level up to 220kV. It integrates protection,control and monitoring......

  • Overview
  • Functions
  • Features

The RCS-985TS provides transformer protection for two winding and three-winding main transformers, auxiliary transformers and startup/standby transformers in power plants with voltage level up to 220kV. It integrates protection, control and monitoring functions in one package, providing users with effective and reliable solutions. The RCS-985TS offers differential protection for up to three CT inputs. The RCS-985TS is fully compatible with IEC 61850 communication with an additional communication unit.

Protection and Control
  • Variable slope percent differential protection. (87T)
  • Unrestrained differential protection. (87UT)
  • Restricted earth fault protection. (REF)
  • Phase overcurrent protection. (50/51P)
  • Ground overcurrent protection. (50G/51G)
  • Zero-sequence overcurrent protection. (50/51N)
  • Gap zero-sequence overvoltage protection. (59G)
  • Zero-sequence voltage alarm function. (59G)
  • Overload alarm. (49)
  • Overload initiating cooling. (49)
  • On-load tap change (OLTC) blocking function during overload. (49)
  • CB breaking capacity blocking.
  • Voltage control element. (VCE)
  • Current control element. (CCE)
  • VT circuit failure supervision
  • CT circuit failure supervision
  • CT saturation detection
  • Inrush current detection

Monitoring and communication
  • Self diagnostic
  • DC power monitoring and alarming
  • Event Recorder including 256 statuses change of binary input reports, 64 self-supervision reports and 64 operating reports.
  • Disturbance recorder including 64 fault reports, and 8 waveforms. The maximal record time is up to 15s for single fault waveform. (The file format of disturbance recorder is compatible with international COMTRADE file.)
  • GPS clock synchronization
  • Rear communication ports: Ethernet (Optional) with IEC 61850(additional communication unit) and RS-485 with IEC 60870-5-103 protocol, 1 RS-485 with clock synchronization, 1 RS-232 or RS-485 with printer.

  • On the premise of 24 samples per cycle, all data measurement, calculation and logic discrimination can be completed within one sampling period. The event recording and protection logic calculation are completed simultaneously.
  • The fault detectors in CPU processor are used to supervise tripping outputs. The relay drives the tripping output only when the fault detectors in CPU module and MON module operate simultaneously so as to avoid maloperation caused by hardware component failures.
  • The RCS-985TS can be used as main and backup protection for transformers in power plants. Protection information such as sampled data and binary inputs are shared between all protective elements.
  • The percentage differential protection adopts variable slope restraint characteristics, and the actual unbalanced differential current effect can be simulated. The phase current waveform is identified to prevent maloperation due to CT saturation.
  • The CT current output will be corrected before calculation to eliminate the influence of different CT ratio
  • The harmonics restraint method is used to discriminate inrush current.
  • The CT saturation detecting logic can prevent mal-operation in case of external fault and improve operation performance under the condition of internal fault. For external faults, maloperation can be avoided if the transfer time from primary to secondary side of CT is no less than 5ms.
  • The independent fault detectors in the CPU processor can provide realtime supervision of tripping outputs. The relay will drive the tripping output only when the fault detectors in the CPU module and in the MON module operate simultaneously.
  • The fault detector can record the operational events of analog components, differential current and time sequence protection elements. The latest 8 fault waveforms can be recorded for up to 15s each. The format of fault reports is compatible with the international COMTRADE file.
  • Various GPS clock synchronizations are provided: second/ minute pulse via binary input or RS-485, message via communication ports and IRIG-B synchronization.