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Bus Differential and Breaker Failure Relay

Powerful Solution for Busbar Differential Protection

Select the SEL-487B for the differential protection of busbar systems with up to 18 terminals.

Features and Benefits

I Protection

Protect bus systems with up to 18 terminals (54 CTs), 6 protection zones, and 1 additional independent check zone. To optimize protection security, the check zone supervises up to 6 zones, and a patented open CT detection algorithm blocks potential misoperations during open or shorted CT conditions. Differential and directional current elements provide increased security and fast fault detection. Reduce protection costs with built-in breaker failure protection.

I Flexibility

Implement different ratio CTs and nondedicated CTs with the SEL-487B. Eliminate complex wiring by using CT ratios that differ by up to a factor of 10:1. Take advantage of the same CTs for differential protection, metering, backup relaying, and other functions.

I Automation and Control

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

I Monitoring and Metering

Provide accurate, timely monitoring and metering of busbar, feeder, and substation signals. Terminal currents, breaker and disconnect positions, station dc voltage levels, and threephase voltage are continuously monitored and updated.

Making Electric Power Safer, More Reliable, and More Economical ®

Functional Overview

SEL-487B Relay

Protect up to 18 terminals using SEL-487B Relays.

· · · · · · · · · · · · · Phase-Segregated Measurement Up to 10:1 CT Ratio Mismatch Stability Against CT Saturation CT Supervision Advanced Open CT Detection Logic Single-Relay Application: 2 zones for up to 6 terminals Double-Relay Application: 3 zones for up to 9 terminals Three-Relay Application: 6 zones for up to 18 terminals and three-phase check zone (A, B, C) Dynamic Zone Selection Monitor Logic for 48 Disconnects Breaker Failure Protection for Each Terminal Instantaneous and Time-Overcurrent Elements for Each Terminal Voltage Inputs for Phase, Negative-, and Zero-Sequence Elements

52 T



52 F1 52 F2 52 F3 52 F4 52 F5








SEL-487B Three-Phase Differential Connection

27/59 50 50/BF 51 87

Application uses a single SEL-487B Relay with three-phase differential connection on six or fewer terminals.

52 T


· I/O (Fully Equipped: 1 Main, Up to 4 Optional I/0 Boards)

- Standard Main Board: 7 inputs, 8 outputs - Optional I/O Board: 2 groups of 9 common inputs 6 independent inputs 6 high-speed, high-current outputs 2 standard outputs


52 F1 52 F2 52 F3 52 F4 52 F5 52 F6 52 F17

· · · ·

Expanded SELOGIC® Control Equations Station Battery Monitor Oscillography of 24 Samples Per Cycle 1000 Sequential Events Recorder (SER) Entries, 250 Monitoring Points

- DNP3 LAN/WAN - IEC 61850

7 to 18 Terminals

A-Phase Currents

B-Phase Currents

C-Phase Currents

· Ethernet Options

· Differential Current, Phase Current, and Voltage Metering · Disconnect Status and Travel Monitoring · Four EIA-232 Serial Ports

- DNP3 Level 2 Outstation Protocol - SEL MIRRORED BITS® Communications

SEL-487B A-Phase Differential Connection

SEL-487B B-Phase Differential Connection

SEL-487B C-Phase Differential Connection

Application uses three SEL-487B Relays with single-phase differential connection per relay for 18 terminals.


Differential Protection

The SEL-487B includes six independent current differential elements. Operating time for internal faults is less than one cycle, including highspeed output contact closure. Each SEL-487B differential element provides: · Fast operate times for all busbar faults · Security for external faults with heavy CT saturation · Security with subsidence current present · High sensitivity to busbar faults · Minimum delay for faults evolving from external to internal

20 15 10 Current (Amps) 5 0 5 0 ­5 0 Internal Fault Detection


External faults are detected by directional elements within the relay. When an external fault is detected, the relay enters a high-security mode. In this mode, the relay dynamically selects a higher slope for the differential elements, making them more secure for external faults.

High-Security Operate Slope Standard Operate Slope Restraint Zone CT Supervision Current Input I01 IOP Differential Element

2 pe Slo e 1 Slop

Fault Inception

Trip Output


Current Input I18


IRT External Fault

(<1 cycle)

Fault Detection Logic

Internal Fault

Differential element operation in less than one cycle for internal faults.

100 50 0 ­50 IO1

Current (Amps)

50 0 ­50 IO2

CT Supervision For each zone, sensitive current differential elements detect differential current resulting from a differential element that is not well balanced (i.e., wrong CT ratios). If the conditions persist for longer than a user-specified delay, the element alarms and can be used to generate an external alarm and/or block the zone. Voltage Element Supervise current differential tripping within the relay 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.

­100 ­150 0 Internal Fault Detection (No Differential Element Operation)


Differential element remains secure for external faults with CT saturation.


Breaker Failure Detection

The SEL-487B includes complete breaker failure protection, including retrip, for each terminal. Internal breaker failure is determined by predefined protection schemes that allow different types of trip signals and current flow conditions. External breaker failure device inputs can be substituted for the internal breaker failure schemes, while providing individual or identical responses to each breaker failure condition.

Open-Phase Detection

Open-Phase Detection

IEC 61850 Functionality

IEC 61850 is an international communications protocol standard for self-describing intelligent electronic devices. Streamline design and commissioning by sending standard files to the SEL-487B to easily configure the IEC 61850 messages exchanged with devices from other suppliers. SEL supports IEC 61850 protocol with primary and backup optical-fiber and copper options to perform automation, control, and protection communications.

High-speed, open-pole detection logic detects open-pole conditions in less than 0.75 cycle to reduce breaker failure coordination times.

Overcurrent Elements

Choose from ten overcurrent curves for each current input. Each torque-controlled, time-overcurrent element has two reset characteristics. One choice resets the element if the current drops below pickup for one cycle, while the other choice emulates the reset characteristic of an electromechanical induction disk relay. In addition to the time-overcurrent elements available from the curves, one level of instantaneous and definite-time elements is available for each current input.

Dynamic Zone Configuration

The SEL-487B dynamically assigns the input currents to the correct differential elements without the need for additional auxiliary relays. Connect the digital inputs from the busbar disconnect and breaker auxiliary contacts directly to the relay. SELogic control equations and zone selection logic will correctly assign the currents to the differential elements, even for complex bus arrangements as shown (right). Note that the SEL-487B automatically includes the Zone 4 currents in Zone 3 when Disconnect Switch DS3 is closed (lower right).


Advanced Open CT Detection Logic

The patented open CT detection logic improves the security of the current differential element. It assures current differential bus zones will not misoperate due to terminals that cannot be properly measured. This advanced logic, when implemented, will block differential element misoperations that occur under open or shorted CT conditions. The CT detection logic monitors the CT terminals in every bus zone to detect when a contributing CT has failed.

Independent Bus Check Zone Supervises Up to Six Differential Zones

In complex busbar layouts, the SEL-487B Relay uses disconnect auxiliary contact status to define current differential bus zones. When disconnect auxiliary contacts fail or become misaligned, the relay could misoperate, tripping a zone that has no fault. To avoid this misoperation, supervise your bus zone differential protection with the independent "check zone" in every relay. Bus Check Zone Key Features · Provides secure supervision for bus zones · Supervises bus zones independent of terminal auxiliary disconnect status · Processes its logic independent of all differential bus zones · Independent pickup and slope settings allow check zone to be set for a wide variety of applications and protection philosophies

Check Zone Zone 1 52 Zone 2

52 52


52 52





Zone 1

Zone 2

Check Zone

This is a basic example of a check zone supervising only two three-phase zones, with one SEL-487B per phase. These three SEL-487B Relays can supervise up to six three-phase differential zones.

Three-Relay Bus Protection Application--For Up to 18 Terminals A check zone is provided in every relay, allowing a single-phase check zone per relay. A three-phase (A,B,C) check zone will require three relays. Configure a check zone for every phase, encompassing all terminals at the station (except bus coupler and sectionalizing breakers), independent of disconnect auxiliary contact status.





QuickSet® SEL-5030 Develop SEL-487B settings and busbar configurations offline with acSELErator QuickSet. The system automatically checks interrelated settings and highlights out-of-range settings. Settings created offline can be transferred by using a PC communications link with the SEL-487B. Graphical Logic Editor (GLE) Simplify the process of configuring your SEL-487B using the GLE in acSELErator QuickSet Designer. The GLE allows you to view your SELogic equations graphically, so your settings files can be documented for easier validation and commissioning. Convert existing SELogic control equations to easy-to-read diagrams, and save diagrams with your QuickSet settings. With the GLE capability in acSELErator QuickSet Designer® SEL-5031 Software, design new SELogic control equations using the convenient diagram navigation tool, drag-and-drop interface, function block diagrams, and the automatic layout function. Manage your control diagrams with a full element palette. The GLE will aid in reducing design errors as well as time and expense in commissioning relays.


graphical logic editor (GLE).


Automation and Control

The SEL-487B control logic can replace the following: · Traditional panel control switches · RTU-to-relay wiring · Traditional latching relays · Traditional indicating panel lights · Panel meters Eliminate traditional panel control switches with 32 local control points. Set, clear, or pulse local control points with the programmable front-panel pushbuttons and display. Program the local control points to implement your control scheme via SELogic control equations. Eliminate RTU-to-relay wiring with 32 remote control points. Set, clear, or pulse remote control points via serial port commands. Incorporate the remote control points into your control scheme via SELogic control equations. Apply remote control points for SCADA-type control operations, such as trip and group selection.

Advanced Display and Controls for Next-Generation Substation Automation and Integration

Rotating display automatically scrolls between custom metering displays, alarms, event summaries, and preconfigured fundamental line quantity displays. SEL provides a worldwide, ten-year product warranty and --40° to +85°C operating temperature range--the best in the industry. Easy-to-use keypad aids simple navigation and set-point adjustment. Detailed, programmable target LEDs, with user-configurable labels, give fast and simple information to assist dispatchers and line crews in rapidly restoring power. Optionally, add eight tricolored target LEDs.

Breaker status indication.

Enhanced Front-Panel HMI Improve efficiency and simplify installation with more target LEDs and operator buttons. The 7U and 9U chassis have options for an additional eight target LEDs and four operator control buttons.

The front-panel LCD shows the latest 200 of the 1,000 events time-stamped in the Sequential Events Recorder (SER).

Programmable operator pushbuttons and configurable labels provide local switches to replace traditional panel switches. Optionally, add four tricolored operator pushbuttons to control even more circuit breakers.

· Indicate relay state and various

Service control switch. trip conditions with 24 target LEDs, or configure them for specific applications.

· Meet operator control needs by

modifying the 12 operator buttons to replace traditional panel switches, and control more circuit breakers.


Monitoring and Metering

Access a wide range of useful information in the relay with the metering function. · Metering quantities include primary and secondary voltage and current magnitudes, and angles for each terminal. · Zone information displays primary or secondary current and voltage for each terminal. The polarity of each CT and the bus zones in each of the protective zones at the station are also included. · Differential metering shows the operating and restraint currents for each zone as well as the reference current. · Battery monitoring provides warning and alarm thresholds that can be monitored with the SEL-2032/2030/2020 Communications Processor. Trigger messages via local display, telephone, pager, or other devices. Event Reporting and Sequential Events Recorder (SER) Simplify system testing and post-fault analysis with the SEL-487B event reporting capabilities to help improve understanding of even the most complex protective scheme operations. Coordinated event reports with acSELErator Analytic Assistant ® SEL-5601 Software. Oscillography and Event Reporting User-selected internal or external triggers can be used to generate oscillographic event reports that include voltage, current, and element status information. The SEL-487B stores up to 480 cycles (8 seconds), in either 15-, 30-, 60-, or 120-cycle event reports, at 24 samples per cycle in nonvolatile memory. Relay settings are appended to the end of each report. Analytic Assistant® SEL-5601 Software helps you compare event reports from multiple relays, enhancing this powerful tool's analytic capabilities. Event Summary Each time the relay generates a standard event report, it also generates a corresponding event summary. The event summary is a concise report of the event, containing pertinent information about the time, type, and ac signal magnitudes as well as the terminals and zones affected by the event. With an appropriate setting, the relay will automatically send an event summary in ASCII text to one or more serial ports each time an event report is triggered. SER Gain a broad perspective of relay element operation with the SER in the SEL-487B. Items that trigger an SER entry are selectable and can include as many as 250 monitoring points, such as input/output, change of state, element pickup/dropout, and more. The relay SER stores the latest 1,000 events, which are available through the SER command. The latest 200 events are also viewable via the frontpanel LCD. Ethernet Communications Retrieve oscillographic event report data, transfer SCADA information, manage settings, and more through optional Ethernet communications. Supports FTP, Telnet, DNP3 LAN/WAN, and IEC 61850.


Security during external fault with CT saturation.

Relay remains secure during MOV arrester conduction.


SEL-487B Bus Differential and Breaker Failure Relay

General Specifications

AC Current Inputs (secondary circuits) 5 A nominal 15 A continuous, linear to 100 A symmetrical, 500 A for 1 second, 1250 A for 1 cycle Burden 0.27 VA @ 5 A; 2.51 VA @ 15 A 1 A nominal 3 A continuous, linear to 20 A symmetrical, 100 A for 1 second, 250 A for 1 cycle Burden 0.13 VA @ 1 A; 1.31 VA @ 3 A AC Voltage Inputs 300 VL-N continuous (connect any voltage up to 300 Vac) 600 Vac for 10 seconds Burden 0.03 VA @ 67 V; 0.06 VA @ 120 V; 0.8 VA @ 300 V Power Supply 125/250 Vdc or 120/240 Vac Range 85--300 Vdc <35 W or 85--264 Vac (30--120 Hz) Burden <120 VA 48/125 Vdc or 120 Vac Range 38--140 Vdc <35 W or 85--140 Vac (30--120 Hz) Burden <120 VA 24/48 Vdc Range 18--60 Vdc Burden <35 W Station DC Battery System Monitor Specifications Operating Range 0--350 Vdc Input Sampling Rate 24 samples per cycle Processing Rate 1/6 cycle Maximum Operating Time ±1.5 cycles (all elements but DC1R) ±1.5 seconds (element DC1R) Setting Range DC Settings OFF, 15--300 Vdc, 1 Vdc steps AC Ripple Setting 1--300 Vac, 1 Vac steps Accuracy Pickup Accuracy ±3%, plus ±2 Vdc (all elements but DC1RP) ±10%, plus ±2 Vdc (DC1RP) Serial Communications Ports Three rear-panel and one front-panel EIA-232 ports SEL ASCII Commands, SEL Fast Messages, DNP3 Serial Data Speed 300--57600 bps Ethernet Communications Options Provides IEC 61850, DNP3 LAN/WAN, FTP, and Telnet protocols. Ethernet connection media options: 10/100BASE-T Twisted-Pair Network 10/100BASE-FX Fiber-Optic Network1 Metering Accuracy All metering accuracies are based on an ambient temperature of 20°C and nominal frequency. Instantaneous Differential Metering Per Zone ±5.0%, ±0.02 · INOM IOP, IRT Per-Phase Instantaneous Metering and V01, V02, and V03 I01, I02, . . ., I18 ±3% ±0.004 · INOM , ±2.0° Conformal Coating Option Protect equipment from harsh environments and airborne contaminants, such as hydrogen sulfide, chlorine, salt, and moisture. Chassis Options 9U chassis supports up to 4 optional I/O boards 7U chassis supports up to 2 optional I/O boards

Relay provides many I/O port options (9U version shown).


Eye-safe, Class 1 LED device per EN 60825-1

Pullman, Washington USA Tel: +1.509.332.1890 · Fax: +1.509.332.7990 · · [email protected]

© 2005--2010 by Schweitzer Engineering Laboratories, Inc. PF00063 · 20100416



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