Project Description

SEL-587Z High-Impedance Differential Relay

SEL-587Z High-Impedance Differential Relay
The SEL-587Z Relay is a flexible high-impedance differential relay that combines time-proven high-impedance analog technology with the advantages of microprocessor technology. Use event reports and Sequential Event Recorder (SER) for quick post-event analysis.

Functional Overview

50 (P,G,Q) Overcurrent (Phase, Ground, Neg. Seq.)
51 (P,G,Q) Time-Overcurrent (Phase, Ground, Neg. Seq.)
87 Three-Phase Current Differential
DFR Event Reports
HMI Operator Interface
LGC Expanded SELogic Control Equations
MET High-Accuracy Metering
SER Sequential Events Recorder

* Optional


Front- and Rear-Panel Diagrams

SEL-587Z Front Panel SEL-587Z Rear Panel
Front Rear



Use high-impedance differential elements for fast tripping for in-zone faults, while providing security during heavy through faults and CT saturation. Reduce panel design cost and space requirements by using a single relay that includes three-phase protection, resistors, and metal oxide varistors (MOVs).


Use front-panel pushbuttons to save the expense of separately mounted control switches. Serial port communication provides for remote control of circuit breakers or other user-defined functions.

Reporting, Monitoring, and Metering

Simplify fault analysis with event reports and Sequential Events Recorder (SER). Validate CT connections using the metered voltagedifferential quantities.


Integrate the relay with SCADA, local HMI, or modems using Modbus®, SEL ASCII, and SEL Fast Messaging protocols through the rear-panel isolated communications port. Use the front-panel communications port for relay settings and event report retrieval


487B 587Z
Breaker Failure Protection f
Bus Differential
High-Impedance Bus Differential
Low-Impedance Bus Differential
Three-Phase Current Inputs 7/10
Three-Phase Voltage Inputs 1
27/59 Under-/Overvoltage
46 Current Unbalance f
50 (N,G) Overcurrent (Neutral, Ground)
50P Phase Overcurrent
50Q Negative-Sequence Overcurrent
51 (N,G) Time-Overcurrent (Neutral, Ground)
51P Phase Time-Overcurrent
51Q Negative-Sequence Time-Overcurrent
87 Current Differential
87Z High-Impedance Differential
Single-Pole Trip/Close
Three-Phase Differential Bus Zones 2/3/6 1
Check Zones 3
79 Automatic Reclosing f
Dynamic Zone Selection
SELogic Control Equations
Nonvolatile Latch Control Switches
SELogic Remote/Local Control Switches
Display Points
Multiple Settings Groups
Substation Battery Monitor
Event Report (Multicycle Data)
Sequential Events Recorder
Instantaneous Meter
Demand Meter
IEC 61850 +
Built-In Web Server
Simple Network Time Protocol (SNTP)
Mirrored Bits Communications
Parallel Redundancy Protocol (PRP)
Connectorized (Quick Disconnect) Available +
Standard Feature
+ Model Option
f This function may be created using settings

Product Literature