Project Description

SEL-710-5/SEL-710 Motor Protection Relay

SEL-710-5 Motor Protection Relay

Protect asynchronous (induction) and synchronous motors with one SEL-710-5 Motor Protection Relay. New features include broken rotor bar detection and variable-frequency drive (VFD) support as well as options for arc-flash detection, differential protection, and synchronous motor protection. The synchronous option also includes, at no additional cost, a voltage divider accessory to interface with the motor excitation system.

Functional Overview

14 Speed Switch
27 Undervoltage
37 (P,C) Underpower/Undercurrent
38 Bearing Temperature
40 Loss-of-Field
46 Current Unbalance
47 Phase Reversal
49P PTC Overtemperature
49R RTD Thermal
49T Thermal Model
50 (P,G,Q) Overcurrent (Phase, Ground, Neg. Seq.)
50N AF Arc-Flash Neutral Overcurrent
50P AF Arc-Flash Phase Overcurrent
50P LR Locked Rotor
50P LJ Load Jam
50N Neutral Overcurrent
51 (P,G,Q) Time-Overcurrent (Phase, Residual, Neg. Seq.)
55 Power Factor
59P Phase Overvoltage
60 Loss-of-Potential
66 Starts-Per-Hour
78 Out-of-Step
81 (O,U) Over-/Underfrequency
87 Current Differential
90 Load Control
50/51 Adaptive Overcurrent
85 RIO SEL Mirrored Bits Communications
AFD Arc-Flash Detector
BBD Broken Rotor Bar Detection
DFR Event Reports—Motor Starts, Motor Operating Statistics
ENV Optional SEL-2600 RTD Module
HMI Operator Interface
LDP Load Data Profiling
LGC SELogic Control Equations
MET High-Accuracy Metering
RTU Remote Terminal Unit
SDTM Slip-Dependent AccuTrack Thermal Model
SER Sequential Events Recorder
SM Synchronous Motor Control and Protection
VAR Reactive Power
VFD Variable-Frequency Drive Support

* Optional


Front- and Rear-Panel Diagrams

SEL-710-5 Front Panel SEL-710-5 Rear Panel
Front Rear


Multiple Applications

The SEL-710-5 Motor Protection Relay is a full-featured, multifunctional relay that provides complete ac induction and synchronous motor protection and control, including automatic starting. The SEL-710-5 can be implemented for a wide variety of applications, such as fans, blowers, compressors, air handlers, pumps, conveyors, chippers, crushers, screeners, feeders, augers, and bucket elevators.

Standard Motor Protection

Standard features include SEL’s trusted current-, voltage-, and thermal-based motor protection with current differential. The powerful thermal model dynamically calculates motor slip to provide precise temperature tracking with less time required between restarts and more time during the start sequence.

Synchronous Motor Protection and Starting

The SEL-710-5 provides two levels of field over- and undervoltage, field over- and undercurrent, and field resistance protection as an option. It provides automatic synchronization by applying the dc field voltage to the motor field at the correct slip frequency and rotor angle to lock the motor to synchronous speed. It also includes out-of-step and loss-of-field protection.

Arc-Flash Protection

Overcurrent-supervised arc-flash protection provides secure arc-flash tripping by operating when both arc-flash and overcurrent conditions occur. This important feature improves worker safety in areas where high fault current and high incident energy arc-flash events are possible.

Broken Rotor Bar Detection

The broken rotor bar feature detects and reports signature sideband frequencies—current signature analysis (CSA)—that occur in the presence of broken rotor bars. Early detection reduces maintenance costs and helps prevent associated thermal and mechanical damage contributing to catastrophic motor failure.

Flexible Communications

Advanced protocols, such as IEC 61850, DNP3, Modbus TCP/IP, Modbus RTU, Telnet, FTP, SNTP, and ASCII, support communication with legacy and modern supervisory and control systems.

Reliable Rugged Hardware

The SEL-710-5 operates in extreme conditions, with an operating temperature range of –40° to +85°C (–40° to +185°F), and is designed and tested to exceed applicable stan-dards, including vibration, electromagnetic compatibility, and adverse environmental conditions.



749M 701 849
Induction Motor Protection
Synchronous Motor Protection +
Feeder Protection
Breaker Failure Protection f f
Equipment Thermal Monitoring + + +
27/59 Under-/Overvoltage + + +
32/37 Directional/Underpower Elements + + + +
40 Loss-of-Field +
46 Current Unbalance
47 Phase Reversal
49 Thermal
50 (P,N,G) Overcurrent (Phase, Neutral, Ground)
50Q Negative-Sequence Overcurrent
51 (N,G) Time-Overcurrent (Neutral, Ground)
51 (P,Q) Time-Overcurrent (Phase, Neg. Seq.)
55 Power Factor + +
60 Loss-of-Potential + f f +
78 Out-of-Step +
81 Over-/Underfrequency + +
87 Current Differential +
Arc-Flash Detection +
Separate Neutral Overcurrent
Broken Rotor Bar Detection +
SELogic Control Equations/Remote Control Switches
Nonvolatile Latch Control Switches
Multiple Settings Groups
Breaker Wear Monitor
Event Report (Multicycle Data)/Sequential Events Recorder
Demand Meter
Load Profile Report
RTD (Resistance Temperature Detector) Inputs + + +
Ethernet +
IEC 61850 + +
Simple Network Time Protocol (SNTP)
Modbus TCP
Modbus RTU Outstation
Synchrophasors With IEEE C37.118 Protocol
Mirrored Bits Communications
DeviceNet + +
Accepts Wye or Open-Delta Voltage Transformers + + +
Standard Feature
+ Model Option
f This function may be created using settings

Product Literature