Product Description

Generator Protection Relay

The SEL-700G is the right solution for utility and industrial generator protection, with an autosynchronizer, flexible I/O, and advanced communications. It provides a complete protection and synchronization solution for synchronous generators, so you can eliminate the complexity and cost of standalone synchronizer packages. Integrating the synchronization capability into the generator protection relay provides the most cost-effective and reliable solution.


The 5-inch, 800 x 480 color touchscreen display option allows you to directly set, monitor, and control your system, including up to five two- or three-position disconnect switches. A small form factor and multiple mounting adapters make it easy to upgrade protection without cutting or drilling existing cutouts. You can quickly integrate the SEL-700G into serial- or Ethernet-based communications with IEC 61850 Edition 2, EtherNet/IP, the IEEE 1588 Precision Time Protocol (PTP), IEC 60870-5-103, the IEC 62439 Parallel Redundancy Protocol (PRP), Mirrored Bits communications, Modbus, DNP3, and other protocols.



Comprehensive Generator Protection—Connect the SEL-700G across small, medium, or large generators for complete primary and backup protection. The SEL-700GT provides an IEEE 1547-compliant intertie protection solution for distributed generation. Adding the optional neutral voltage connection to the SEL-700G provides 100 percent stator ground protection, based on third-harmonic voltage measurements. You can connect the neutral current input to protect solidly grounded or resistance-grounded machines.

Autosynchronizer—Replace external generator control and synchronizer relays with the built-in automatic synchronizer function. You can also visualize and synchronize system parameters on the device using the available color touchscreen display. The SEL-700G automatically synchronizes frequency, voltage, and phase control and connects the generator to the power system. A PC-based synchroscope and generator start reports allow you to monitor the generator synchronization process.

Current Differential Protection—Apply sensitive percentage-restrained current differential elements and an unrestrained element, along with synchronism check and volts-per-hertz elements, to protect both the generator and the step-up transformer. Optional current differential elements detect stator faults using a secure, sensitive current differential function. Power transformer and CT connection compensation allows the unit step-up transformer to be included in the generator differential zone.

Breaker Wear Monitoring—Record accumulated breaker contact wear with the breaker monitor function, which uses the manufacturer’s specifications for defining breaker operation limits. The internal monitor tracks the total number of close/open operations and integrates the interrupted current per phase. You can set an alarm to alert operators when measured and accumulated quantities approach maintenance thresholds. This information facilitates proactive breaker maintenance and replacement without underutilizing resources.

Easy Communications—Choose from single or dual ports, copper or fiber-optic Ethernet or serial communications, and several protocols, including IEC 61850 Edition 2, EtherNet/IP, IEC 60870-5-103, IEEE 1588 PTP, IEC 62439 PRP, Mirrored Bits communications, Modbus, DNP3 serial, and DNP3 LAN/WAN. Multiple Modbus TCP or Modbus serial sessions are available for custom configuration of your application.

Islanding Detection—The optional vector-shift function (78VS) and rate-of-change-of-frequency protection (81RF) support islanding detection.

Reliable Protection in Harsh Environments—The SEL-700G operates in extreme conditions, with an operating temperature of –40° to +85°C (–40° to +185°F), and it is designed and tested to exceed applicable standards, including vibration, electromagnetic compatibility, and adverse environmental conditions. In addition, the SEL-700G is ATEX-certified and Underwriters Laboratories (UL) Class I, Division 2-certified for use in hazardous and potentially explosive environments.


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