SEL-421的具体参数与选择资料

　　SEL-421的具体参数与选择资料

　　Protection, Automation, and Control System
　　Apply the SEL-421 Protection, Automation, and Control System for high-speed distance and directional protection and complete control of a two-breaker bay.
　　Protect any transmission line using a combination of five zones of phase- and ground-distance and directional overcurrent elements. A graphical user interface system provides logic and application templates for typical line protection schemes. Patented Coupling Capacitance Voltage Transformer (CVT) transient overreach logic enhances the security of Zone 1 distance elements. Best Choice Ground Directional Element logic optimizes directional element performance and eliminates many directional settings. Optional additional logic prevents Zone 1 overreach on series-compensated lines. Optional incremental components provide subcycle operation for application on critical lines requiring high-speed fault clearing.
　　BUDGETARY RETAIL
　　$6,930
　　FEATURED APPLICATIONS
　　Subcycle Distance Protection—Protect critical transmission lines with high-speed quadrilateral, mho distance, and directional elements. Optional subcycle distance elements and series compensation logic reduce operating times to improve system stability.
　　Single- or Three-Pole Operation—Incorporate programmable single- and three-pole tripping and reclosing of one or two circuit breakers into an integrated substation control system. Provide complete bay control with synchronism and voltage checks from multiple sources.
　　Series-Compensated Transmission Lines—Detect faults beyond a series capacitor and prevent Zone 1 overreach on series-compensated lines using the optional logic in the SEL-421-5 Protection, Automation, and Control System.
　　Communications-Assisted Tripping Schemes—Configure protection for transmission lines without any need for external coordination devices. The SEL-421 includes settings for permissive overreaching transfer trip (POTT), two-channel permissive overreaching transfer trip (POTT2), phase-segregated permissive overreaching transfer trip (POTT3), directional comparison unblocking (DCUB), and directional comparison blocking (DCB) schemes.
　　Out-of-Step Blocking and Tripping—Select from either out-of-step blocking of distance elements or out-of-step tripping during power swings. The relay includes multizone elements and logic for detection of an out-of-step condition.

　　Dual CT Applications—Apply the SEL-421 with ring-bus, breaker-and-a-half, or other two-breaker schemes. Combine currents within the relay from two sets of CTs for protection functions, but keep them separay available for monitoring and station integration applications.
　　Underfrequency Load Shedding—Operate six levels of frequency elements as either an underfrequency or an overfrequency element. The frequency elements are suited for applications such as underfrequency load shedding and restoration control systems.
　　Bay Control, Reclosing, and Breaker Failure Protection—Apply complete bay control, reclosing, and breaker failure protection for two breakers. Monitor circuit breaker performance, including average and last tripping time, compressor run time, and contact-interrupting duty.　　

SEL-421的具体参数与选择资料