SEL SEL-421 Protection, Automation, and Control System

SEL-421

Protection, Automation, and Control System

Apply the SEL-421 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 capacitor voltage transformer (CCVT) 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.

Transform the way you modernize your substation with optional Time-Domain Link (TiDL) technology or Sampled Values (SV)-based technology using IEC 61850-9-2 or IEC 61869-9.

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.

You can invert individual or grouped CT or PT polarities to account for field wiring or protection zone changes.

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 separately available for monitoring and station integration applications.

Thermal Overload Protection—Use the three independent IEC 60255-149 thermal elements to activate a control action, issue an alarm, or trip when equipment overheats as a result of adverse operating conditions.

The SEL-2600 RTD Module can provide ambient temperature measurements.

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.

Digital Secondary System Technologies—SEL TiDL and SV-based solutions replace copper with fiber to increase safety, improve reliability, and limit the impact of an electromagnetic pulse.

Apply the SEL-421-7 TiDL relay with the SEL-TMU TiDL Merging Unit in the field to provide remote I/O and digitize analog signals.

This simple point-to-point solution with a strong cybersecurity posture is easy to implement.

Apply the IEC-compliant SEL-421-7 SV relay to receive SV data from a remote merging unit via a network, or apply it as an SV merging unit to publish data to SV relays in the control house.

Improve system availability in SV applications with the Parallel Redundancy Protocol (PRP), the High-availability Seamless Redundancy Protocol (HSR), or seamless failover using a five-port Ethernet card.

Flexible Communications Options—Use small form-factor pluggable (SFP) transceivers on designated process bus, station bus, and engineering access ports in the five-port Ethernet card.

Choose between single- and multimode communications options for increased flexibility. All ports support 100 Mbps SFP transceivers, and process bus ports also support 1 Gbps SFP transceivers.

Product    Revision    Firmware ID

SEL-421-0    R204-V0    SEL-421-R204-V0-Z007007-D20090105

SEL-421-1    R204-V0    SEL-421-1-R204-V0-Z007007-D20090105

SEL-421-2    R131    SEL-421-2-R131-V0-Z100011-D20130627

SEL-421-3    R131    SEL-421-3-R131-V0-Z100011-D20130627

SEL-421-4    R334-V2    SEL-421-4-R334-V2-Z034015-D20251103

SEL-421-5    R334-V2    SEL-421-5-R334-V2-Z034015-D20251103

SEL-421-7    R413-V1    SEL-421-7-R413-V1-Z111004-D20251103