html{display:none} SEL-487B Bus Differential and Breaker Failure Relay | Schweitzer Engineering Laboratories


Bus Differential and Breaker Failure Relay

The SEL-487B provides optimized, low-impedance bus differential fault detection by using high-speed, subcycle protection coupled with high-security operation for external faults. Superior protection performance is combined with integrated station automation features for seamless transition into new and retrofit applications. Optional Time-Domain Link (TiDL) technology and SEL Sampled Values (SV) technology using IEC 61850-9-2 transform the way you modernize your substation.

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Starting At

$7,070 USD

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Low-Impedance Bus Differential Protection—Provide flexible low-impedance bus differential protection for various busbar topologies and sizes. You can protect systems with up to 21 three-phase bus terminals by using three relays to provide 6 three-phase differential bus zones and 3 independent check zones. Patented open CT detection algorithms block potential misoperations due to open or shorted CT conditions.

Integrated Overcurrent Protection—Choose from ten overcurrent curves for each current input for additional protection. Each torque-controlled time-overcurrent element has two reset characteristics. There is also one level of instantaneous and definite-time elements available for each current input.

Voltage Elements—Supervise current differential tripping within the relay by using voltage elements. Three separate voltage elements consist of two levels of phase under- and overvoltage elements and two levels of negative- and zero-sequence overvoltage elements for each of the three analog voltage quantities measured.

10:1 CT Ratio Mismatch—Install the SEL-487B in a system with nondedicated CTs, with CT ratio mismatches up to 10:1. This allows the same CTs to be used in other protection applications, such as metering or backup relaying.

Dynamic Zone Configuration—Automatically reassign current inputs to different bus zones without using auxiliary relays. The SEL-487B is suited for bus topologies that include bus-tie breakers and disconnects.

Breaker Failure Detection—Mitigate circuit breaker failure with the SEL-487B Relay’s integrated circuit breaker failure detection and logic, which includes retrip capability for each terminal.

Integration and Automation—Select from an array of communications features and protocols to integrate the SEL-487B into your existing communications schemes. The relay features EIA-232 as well as optional copper or fiber Ethernet ports to fit into an array of applications. Protocol options include Mirrored Bits communications, DNP3 LAN/WAN, the Simple Network Time Protocol (SNTP), the Parallel Redundancy Protocol (PRP), the IEEE 1588 Precision Time Protocol Version 2 (PTPv2), and IEC 61850 Edition 2.

Digital Secondary System Technologies—TiDL and SEL SV technologies for digital secondary systems replace copper with fiber to increase safety, reduce costs associated with using copper, improve reliability, and limit the impact of an electromagnetic pulse. Apply the TiDL-enabled SEL-487B-1 with the SEL-2240 Axion TiDL nodes in the field to provide remote I/O and communicate digitized analog signals over fiber optics. This simple and secure solution is easy to implement, with no external time source or network engineering required. Apply the SEL-487B-2 with SV technology to receive IEC 61850-9-2 SV data from a remote merging unit.

Distributed Bus Protection—Apply the SEL-487B in a distributed bus protection scheme using TiDL technology. The system is easily scalable for the number of bays in your system, and it does not require special communications ports or network engineering. TiDL’s point-to-point architecture simplifies fiber-optic cable routing in the field and makes the commissioning process quick and easy.

SEL-487B-1 Protection, Automation, and Bay Control System

487B front visual motion

From the front panel, control and view the status of disconnects and breakers, program operator pushbuttons, and configure labels. LEDs with custom alarms help dispatchers and line crews rapidly restore power.

SEL-487B-1 Without TiDL Technology

487B back visual motion

The 21 current and 3 voltage channels accommodate different busbar configurations. Front and rear EIA-232 serial ports and a rear Ethernet port provide communications.

SEL-487B-1 With TiDL Technology

487B back tidl

Fiber-optic ports on the 4U chassis allow the relay to receive analog and digital data from remote TiDL nodes. Commissioning is easy with the press of a button. LEDs indicate a valid configuration as well as the connection status to a remote TiDL node on a per-port basis.

SEL-487B-2 Relay With IEC 61850-9-2 Sampled Values

487B back sv

Receive digitized current and voltage information from remote merging units. On this 4U chassis, you can select fiber optics, copper, or mixed Ethernet with separate ports for SV data and engineering access. The Ethernet links are self-monitoring.


How to Commission a Distributed Bus System With TiDL™-Enabled SEL-487B and SEL-2240 Axion®

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How to Commission a Distributed Bus System With TiDL™-Enabled SEL-487B and SEL-2240 Axion®

Provide flexible, subcycle, low-impedance bus differential protection for various busbar topologies and sizes with the SEL-487B. You can protect systems that have up to 21 three-phase bus terminals by using three relays to provide 6 three-phase differential bus zones and 3 independent check zones. To optimize protection security, the check zones supervise the system on a per-phase basis and a patented open-CT detection algorithm blocks potential misoperations during open- or shorted-CT conditions. Directional and low-impedance differential current elements provide increased security and fast fault detection. Built-in breaker failure protection reduces protection costs.

Apply the same CT for differential protection, metering, backup relaying, or other functions. The SEL-487B Relay can use nondedicated CTs with ratio mismatches up to 10:1.

Automation and Control
Reduce project costs and simplify interconnect wiring using multiple communications protocols. Configurable operator controls and simplified variable naming provide added power to SELogic control equations.

Monitoring and Metering
Provide accurate, timely monitoring and metering of busbar, feeder, and substation signals. Terminal currents, breaker and disconnect positions, station dc power levels, and three-phase voltage are continuously monitored and updated. You can eliminate external recorder and metering requirements with oscillographic and binary COMTRADE event reports and Sequential Events Recorder (SER) reporting.

acSELerator QuickSet SEL-5030 Software
Develop relay settings offline, program SELogic control equations, and analyze post-fault event reports.

Three Independent Check Zones
Improve power system availability and reliability by reducing unintentional relay operations due to failed or misaligned disconnect auxiliary contacts, and provide redundant verification of in-zone faults. Independent check zone settings offer additional flexibility for adjusting the check zone differential element.

Advanced Open CT Detection
Improve the security of the current differential element with patented open CT detection logic. It assures current differential bus zones will not misoperate due to terminals that can’t be properly measured.

Enhanced Front-Panel HMI
Improve efficiency and simplify installation with more target LEDs and operator pushbuttons. The 7U and 9U chassis have options for an additional 8 target LEDs and 4 operator pushbuttons, providing 24 target LEDs and 12 operator pushbuttons on the front-panel HMI.

Time-Domain Link Technology
Apply a TiDL solution, where Axion TiDL nodes are placed in the yard close to the primary equipment to digitize discrete I/O signals and analog data and then transport them over a fiber-optic cable to the SEL-487B in the control house. This innovative technology uses point-to-point connections and a nonroutable protocol, providing a simple and secure solution. Because it does not need an external time source or Ethernet switches, it is easy to implement with no network engineering required. TiDL combines the proven protection of the SEL-400 series relays with the modularity of the Axion, reducing training requirements and providing a scalable and flexible solution. It also provides built-in time synchronization and synchronous sampling, ensuring protection is available in the relay regardless of whether an external time signal is available.

SEL Sampled Values Technology
Implement an SEL SV solution, where the merging unit (publisher) digitizes analog signals from primary equipment and then transmits them to an SEL-487B-2 Relay (subscriber) in the control house via a fiber-based Ethernet network. The system uses precise time synchronization via IRIG-B or PTP. The SEL-487B-2 Relay offers the traditional protection available in the SEL-487B-1 and can also receive SV data from devices such as the SEL-401 Protection, Automation, and Control Merging Unit or the SEL-421-7 Protection, Automation, and Control System Merging Unit. Because all SEL SV devices are compliant with IEC 61850-9-2 and the UCA 61850-9-2LE guideline, the SEL-487B-2 can be used with other manufacturers’ SV-compliant units.

  • Digital secondary system solutions
    • SEL-487B-1 Relay with TiDL technology
    • SEL-487B-2 Relay (subscriber) with IEC 61850-9-2 Sampled Values
  • 1 A or 5 A CT inputs.
  • Ethernet connection options for primary and standby connections:
    • 10/100BASE-T
    • 100BASE-FX
  • IEC 61850 Edition 2 communications and IEEE 1588 Precision Time Protocol Version 2 (PTPv2).
  • Add up to four expansion I/O cards with options for standard or high-speed contact outputs.
  • Rack- or panel-mount hardware packages.
  • Relay configurations:
    • One relay for up to 7 terminals and 2 three-phase zones.
    • Two relays for up to 10 terminals and 3 three-phase zones.
    • Three relays for up to 21 terminals and 6 three-phase zones.
    • Contact your local SEL sales representative for techniques on covering even larger systems.
  • Enhanced HMI with 24 target LEDs, 12 operator pushbuttons, and tricolor LEDs.
  • Connectorized hardware configuration.
  • Conformal Coating: Protect equipment from harsh environments and airborne contaminants, such as hydrogen sulfide, chlorine, salt, and moisture.


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Minimum QuickSet Version

Product Revision Z Number Minimum Software Version
SEL-487B-1 R313-V0 013
SEL-487B-1 R311-V1 012

Product Certifications