RCS-901 Line Directional Comparison Relay

The RCS-901 relay is a pilot directional protection used as the main and backup protection for transmission lines with stepped distance elements,overcurrent elements, single-pole trip, three-pole trip and auto-reclosing functions. The relay can be......

  • Overview
  • Functions
  • Features

The RCS-901 relay is a pilot directional protection used as the main and backup protection for transmission lines with stepped distance elements, overcurrent elements, single-pole trip, three-pole trip and auto-reclosing functions. The relay can be used to protect the overhead lines and underground cables of all voltage levels, including series compensated lines, double-circuit lines, weak infeed (WI), short lines, extremely long lines, three-terminal lines. It fully supports IEC 61850 communication protocol.


Protection and Control
  • Pilot DPFC (Deviation Power Frequency Variation Component) directional comparison line protection. (85)
  • Pilot zero sequence directional comparison protection. (DEF)
  • DPFC distance protection. (21D)
  • Phase-to-phase distance protection. (21P)
  • Phase-to-ground distance protection. (21G)
  • Directional phase overcurrent protection. (67P)
  • Phase overcurrent protection. (50/51P)
  • Directional zero sequence overcurrent protection. (67N)
  • Zero sequence overcurrent protection. (50/51N)
  • Under/Over voltage protection. (27/59)
  • Time overcurrent protection during VT failure. (51P VT)
  • Time zero sequence protection during VT failure. (51N VT)
  • Switch-onto-fault (SOTF) logic.
  • Power swing blocking (68)
  • Fault detection element under pole discrepancy condition
  • Overload alarm function.
  • Synchronism check. (25)
  • Auto-reclosing (single-pole and three-pole). (79)
  • Voltage and current drift auto adjustment.
  • Self diagnostict.
Monitoring and Metering
  • CT failure supervision.
  • VT failure supervision.
  • Synchro-check voltage failure supervision.
  • Tripping circuit supervision.
  • Fault Recorder.
  • Fault Locator.
  • 64 tripping reports, 64 alarm reports and 64 binary input status change reports.
  • High resolution oscillography of last 24 oscillograms. (Compatible with COMTRADE format)

Communications
  • Pilot communication schemes (PUTT, POTT, WI) with fiber, carrier or other channels.
  • 2 optional Ethernet ports with IEC 61850 or IEC 60870-5- 103 over TCP/IP
  • 2 RS-485 communication rear ports conform to IEC 60870- 5-103 protocol
  • 1 RS-485 communication rear ports for clock synchronization
  • 1 RS-232 communication rear ports or RS-485 for printer
  • 1 RS-232 communication faceplate port for testing and setting
  • GPS clock.
  • The typical operating time is 10 ms for a close-in fault, 15 ms for a fault in the middle of the line, 25 ms for a remote fault.
  • The protection principles of DPFC directional comparison element and DPFC distance element are applied in the relay. It can significantly reduce the pickup time and clear the fault fast. The DPFC directional pilot scheme is sensitive which makes the system reliable. The system adopting this pilot scheme is not affected by series compensated capacitors and doesn’t need a power swing blocking logic.
  • The patented adaptive floating threshold method is adopted, which is insensitive to system unbalance and disturbance. The measuring element can get both high security and high speed simultaneously.
  • The built-in reliable power swing blocking logic can properly supervise the distance elements during a power swing. The power swing blocking logic can make the relay untrip for an external fault and pickup for an internal fault during a power swing.
  • Definite time and inverse time characteristics are both provided of zero sequence overcurrent protection.
  • The relay can receive and transmit the remote tripping commands from and to the opposite terminal via channel.
  • The relay can select the faulty phase and make a phase trip correctly, even for a high resistance fault.
  • The built-in reliable power swing blocking logic can properly supervise the distance elements during a power swing. The power swing blocking logic can make the relay untrip for an external fault and pickup for an internal fault during a power swing.
  • The relay can select the faulty phase and make a phase trip correctly, even for a high resistance fault.
  • Innovative technology to prevent any undesired trip caused by any component failure is adopted. The relay has two independent data acquisition paths, one for a fault detector and the other for protection and its logic. Tripping outputs are supervised by the fault detector to prevent a mal-operation.
  • The relay provides GPS clock synchronization, including message, second pulse, minute pulse, and IRIG-B synchronization.
  • The relay is compatible with multiple protocols- IEC61850 and IEC 60870-5-103. The RCS-901 provides networking interface such as RS485, RS232 and Ethernet port.