PCS-931 Line Differential Relay
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Protection Automation Control PCS-931 Line Differential Relay The PCS-931 relay provides full-scheme current differential and distance protection solutions for transmission lines with highspeed sub-cycle distance element. As well, the pilot scheme of distance protection and earth fault protection are integrated to provide a complete protection solution for the transmission line. The PCS-931 is intended for application on overhead lines and underground cables with diverse voltage levels, including series compensated, double-circuit, heavily loaded, weak infeed (WI), short and long lines. The relay provides dual pilot channels used for redundant tele-communication or three-terminal line application. It can meet the requirements of single-pole or threepole tripping, it also provides single- and/or three-pole autoreclosing functions. The PCS-931 is suitable for single- and dual-breaker applications, providing optional dual CT inputs, dual breaker failure protections, dual breaker auto-reclosing and dual synchro-checks. Additionally, the relay provides the remote/ local control of circuit breaker, disconnector and earth switch. The PCS-931 employs a wide range of innovative patented technologies, such as adaptive restraint threshold, dynamic capacitive current compensation, DPFC (Deviation Power Frequency Component) differential protection and unique power swing blocking releasing logic, guaranteeing accurate and reliable operations. The PCS-931 is compatible with IEC 61850 station bus and process bus applications. It supports IEC 61850-8-1 MMS, GOOSE and IEC 61850-9-2 Sampled Value. The front panel RJ45 port is provided for testing and setting, allowing for easier commissioning and maintenance. Figure 1 PCS-931 Functional Block Diagram 12

Functions Protection and Control • Phase-segregated DPFC differential protection (87L) DPFC (Deviation of Power Frequency Component) percentage differential protection reflects superimposed quantities which can recognize the sensitive protection for high impedance faults. The relay provides dynamic charging current compensation, adaptive restraint threshold and CT saturation detection to improve the reliability of DPFC differential protection. • Phase-segregated current differential protection (87L) Dynamic charging current compensation, adaptive restraint threshold and CT saturation...

Protection Automation Control enabled to substitute the phase-to-ground distance protection which is blocked during VT failure. • Switch-onto-fault (SOTF) logic Switch-onto-fault logic is used to clear the faults during manual closing and auto-reclosing • Unique power swing blocking releasing logic (PSBR) The power swing blocking releasing logic prevents mal-operations during external faults in power swing and quickly clears the internal faults in power swing. • Out-of-step protection (78) • Broken conductor protection (46BC) The ratio of negative to positive phase sequence current (12/ II)...

• Provide some function shortcuts key, which can be configured by PCS-Explorer and be fulfilled by combination key of devices' keypad, to execute some operation quickly. • One front RJ-45 port for testing and setting • One RS-232 or RS-485 rear port for printer • Language selection - English + selected language • Assistant software - PCS-Explorer Features • Innovative dynamic capacitive current compensation is introduced to the relay, in order to compensate both steady-state capacitive current and transient capacitive current, which can increases the sensitivity to high-impedance faults in...