Product Description

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.



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.


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