Differential Relay eliminates need for settings.

Press Release Summary:




Microprocessor-based SEL-387L Line Current Relay suits applications with identical-ratio CTs at both ends of line, with digital communications channel interface between relays. Restraint technology provides secure, high-speed ground fault differential and sensitive phase protection, uncompromised by communication asymmetry, CT saturation, or different in-feeds. Negative- and zero-sequence differential elements detect high-resistance ground faults while remaining secure for external faults.



Original Press Release:



New 'Zero Settings' Relay From SEL Reduces Costs, Effort, and Errors for Two-Terminal Line Applications



With zero settings plus major savings on hardware and installation costs, the new SEL-387L Line Current Differential Relay is a breakthrough solution for many applications with identical ratio CTs at both ends of a transmission line.

(Pullman, WA) Schweitzer Engineering Laboratories, Inc. (SEL) has eliminated the time-consuming and costly tasks of calculating and testing protective relay settings from two-terminal line applications with the introduction of the SEL-387L Line Current Differential Relay. Requiring no settings, the SEL-387L Relay also eliminates the problems of misoperation due to erroneous settings and provides considerable savings on relay hardware costs.

The SEL-387L Relay is ideal for industrial applications where it is used to protect a line going to a plant that owns the substation. Many such users would like to avoid spending the time and money required for setting a relay. With this new, economical relay, installers simply assign the transmit and receive addresses, and the relay is ready to protect transmission lines and cables of any voltage.

"Applying the SEL-387L Relay for line differential protection means zero settings, zero settings errors, zero settings labor, and significant material and engineering cost savings," says Roy Moxley, SEL Senior Marketing Engineer.

The microprocessor-based SEL-387L Relay is designed for applications with identical-ratio CTs at both ends of a line, with a digital communications channel interface (direct or multiplexed) between the relays. While these conditions are not met by every transmission line, there are abundant suitable applications throughout the world.

"There are a lot of activities that go along with setting a relay," Moxley explains. "By eliminating settings, the SEL-387L Relay eliminates engineering effort and the need to test and maintain settings and the corresponding database, saving 10 to 20 hours per relay. Because this relay eliminates incorrect and complex settings, protection security is also improved."

Using the proven restraint technology of the SEL-311L Relay, the new SEL-387L Relay provides secure, high-speed ground fault differential and sensitive phase protection that is not compromised by communication asymmetry, CT saturation, or different in-feeds. Negative- and zero-sequence differential elements detect high-resistance ground faults while remaining secure for external faults. The SEL-387L Relay's comprehensive operating principle, validated by thousands of SEL-311L Relays in use today, ensures that the relay is not susceptible to power swings or overload conditions, such as those that contributed to the August 2003 blackout (as reported by NERC).

Although SEL-387L Relays are designed to protect transmission lines with no taps, one or two SEL-387L Relays may be used with an SEL-311L Relay as an economical solution for tapped load and three-terminal applications.

Complete details on the SEL-387L Relay and applications are available at http://www.selinc.com/SEL-387L.

For more information about this and other SEL products or the location of the SEL representative nearest to you please visit our website at www.selindustrial.com, or contact the SEL Industrial Solutions Group by phone (615) 507-2184; fax (615) 507-2188; e-mail Marketing@selindustrialcom; or mail to 130 Seaboard Lane, Suite A7, Franklin, TN 37067.

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