PCS-902 Line Distance Relay

The PCS-902 relay provides numerical line protection with pilot distance protection, stepped distance protection, current protection, voltage protection, single and/or threepole tripping and auto -reclosing functions. As a full-scheme device......

  • Overview
  • Functions
  • Features

The PCS-902 relay provides numerical line protection with pilot distance protection, stepped distance protection, current protection, voltage protection, single and/or threepole tripping and auto-reclosing functions. As a full-schemedevice, it integrates frequency protection, breaker failure protection and stub protection.

The PCS-902 introduces an extensive functional library, programmable LED, programable logic and configurable I/O, intended for applications on overhead lines and underground cables of all voltage levels, including series compensated lines, double-circuit lines, heavily loaded lines, weak infeed (WI), short lines and extremely long lines.

The PCS-902 adopts a wide range of innovative patented echnologies, such as DPFC (Deviation Power Frequency Component) distance protection and unique power swing blocking logic, to guarantee its accurate and reliable operation.Mho and quadrilateral characteristics are provided for both phase and ground distance protections. 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. It provides the RJ-45 faceplate port for testing and setting to make commissioning and maintenance easier.


Protection and Control
  • Pilot distance protection. (85/21)
    It integrates independent distance zone with PUTT, POTT, Blocking, DTT & Zone Extension.
  • Pilot directional earth-fault protection. (DEF)
    The relay includes directional zero sequence comparison element for earth fault.
  • DPFC distance protection. (21D)
    Innovative Deviation of Power Frequency Component distance protection can quickly clear faults and is immune to the load current, weak-infeed and power swing.
  • Four zones of phase-to-phase distance protection. (21P)
    Four zones of phase-to-phase distance protection integrates the memorized positive sequence voltage polarization, direction characteristic, load blinder and unique low-voltage distance element. The fourth zone can be set as the reverse directional protection.
  • Four zones of phase-to-ground distance protection. (21G)
    Four zones of phase-to-ground distance protection integrates the memorized positive sequence voltage polarization,reactance characteristic, direction characteristic, load blinder and unique low-voltage distance element. The fourth zone is the reverse directional protection.
  • Four stages of directional phase overcurrent protection. (67P,50/51P)
    Overcurrent protection can be supervised by voltage element and directional element. IDMT curves complied with IEC and ANSI standard are available for selection.
  • Breaker failure protection for one or two breakers (50BF)
    Breaker failure protection can be applied to one breaker and two breakers applications.
  • Two stages of under voltage protection and two stages of overvoltage protection (27/59)
    Under/over phase voltage protection and negative/zero sequence overvoltage protection are provided.
  • Four stages of underfrequency protection and four stages of over frequency protection. (81)
    Frequency is calculated reference to the positive sequence voltage. The protection can be supervised by the df/dt element and the undervoltage element.
  • Stub protection for T-Zone in a 1½ breaker arrangements.(50S)
    Stub protection is introduced to protect T-zone in a one-anda- half breaker arrangement or a ring breaker arrangement.
  • Time phase overcurrent protection during VT failure. (51P VT)
    Time phase overcurrent protection will be enabled if the phase-to-phase distance is blocked by VT failure.
  • Time zero sequence overcurrent protection during VT failure. (51N VT)
    Time zero sequence overcurrent protection will be enabled if the phase-to-ground distance protection is blocked by VT failure.
  • Switch-onto-fault (SOTF) logic.
    Switch-onto-fault logic is used to clear fault during manuallyclosing and auto-reclosing.
  • Unique power swing blocking logic. (68)
    The power swing blocking logic can prevent mal-operation during external fault in power swing and clear the internal fault quickly in power swing.
  • Out-of-step tripping (78)
    The out-of-step status is detected in the relay and it can be used to trip the transmission line.
  • Broken conductor protection (46BC)
    The ratio of negative to positive phase sequence current (Ι2/ Ι1) is adopted to detect the broken conduct.
  • Dead zone protection (50DZ)
    It is provided to clear the dead zone fault between CT and breaker.
  • Thermal overload protection. (49)
    The output of thermal overload protection can be set to tripping or alarm.
  • Synchronism check. (25)
    Synchronism check and dead bus or dead line check are both provided for auto-reclosing.
  • Auto-reclosing (single and/or three-pole for one or two breakers). (79)
    Single/three pole auto-reclosing is applicable to one or two breakers. Priority logic is integrated for use on one-and-ahalf breaker arrangement and ring breaker arrangement.
  • Voltage and current drift auto adjustment. The relay continually and automatically traces the voltage and current drifts and adjusts the zero point to the normal value.
  • Frequency tracking. Frequency tracking is provided to accommodate the frequency shift in power system.

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

    Communications
  • Pilot communication schemes (PUTT, POTT, Blocking, DTT, WI).
  • 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 RJ45 front port for testing and setting
  • Clock synchronization via Pulse-Per-Second, IRIG-B and SNTP
  • The typical pickup time is 10 ms for a close-in fault, 15 ms for a fault in the middle of a line, 25 ms for a remote fault.
  • The relay is based on NR’s well established and proven UAPC hardware platform with multi-processor architecture. The multi CPU technology supports parallel operating simultaneously.
  • The binary output can be used to initiate the power line carrier transceiver or other signal channel, and the optical fiber is optional instead of carriers to realize the pilot scheme.
  • The sensitive DPFC distance protection is integrated to target on the quick clearance of internal fault without being affected by power swing.
  • Phase-ground distance protection is provided with zerosequence compensation.
  • The patented adaptive floating threshold is insensitive to system imbalance and disturbance. The measuring element can achieve high security and high speed simultaneously.
  • The unique built-in power swing blocking logic can properly supervise the distance protection during a power swing. The power swing blocking logic can prevent mal-operation for an external fault and quickly clear the internal fault during a power swing.
  • Up to four shots single and/or three pole auto-reclosing with synchro-check and dead line/bus check are provided for multi-breaker configuration. The priority logic of multi-breaker auto-reclosing is integrated.
  • The relay is insensitive to the power source change and can be applied to the weak infeed condition.
  • Instantaneous, definite time and inverse time (IDMT) characteristics are available in phase overcurrent protection and the zero sequence overcurrent protection which can be controlled by directional protection and/or under voltage protection through logic setting.
  • Independent distance protection is designed for pilot scheme to realize PUTT, POTT, Blocking and DTT application. Additional three zones of forward distance protection and one zone of reverse distance protection are provided.
  • Users can select either Mho or quadrilateral characteristics for distance protection. The load blinder function is also integrated.
  • The independent phase selection element can select the faulty phase and make a phase trip correctly.
  • 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 mal-operation.
  • 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.