Line Protection

SEL products lead the industry in reliability. That’s one reason why we’re North America’s most trusted relay manufacturer and a world leader in transmission line protection.

SEL line protection solutions are ideal for improving system stability and security, allowing you to:

  • Locate faults faster and more precisely with the traveling-wave technology in select SEL transmission relays.
  • Simplify protection schemes and enable faster, more secure tripping with time-domain technology.
  • Securely apply distance protection elements and implement communications-assisted tripping.
  • Apply line differential protection to protect long transmission lines and complex systems.
  • Connect weak sources (e.g., wind farms) and inverter-based generation to the utility grid.

With feature-rich SEL relays, you can apply protection, fault-locating, and monitoring solutions with a single piece of equipment. This saves money, increases efficiency, and improves reliability by reducing wiring and configuration complexity.

Distance Protection

Apply distance protection as a primary protection solution or as a backup to line differential schemes. SEL relays can be securely applied on short lines and under heavy load conditions, with or without wide-area communications. Zero-setting out-of-step blocking functions improve system stability without time-consuming and expensive system studies.

Line Differential Protection

Use line differential protection for improved protection of your most critical transmission lines. It’s an ideal solution for long extra-high-voltage lines, for complex systems where distance protection alone is inadequate, and for primary line protection when connecting wind farms to the grid.

Fault Locating

The fault-locating functions built into SEL relays ensure that you can dispatch crews to  precise locations and repair the faulted section quickly. SEL relays can compute fault locations using multiple methods—including traveling-wave fault locating, which locates faults to within one tower span.

Time-Domain Line Protection

Deploy innovative SEL time-domain protection products to simplify protection schemes and enable faster, more secure tripping.

Engineering Services

Let us partner with you to create an SEL solution for your system. From engineering studies and system design through commissioning and training, SEL engineers bring inventiveness and a deep understanding of the fundamental principles of electric power systems to every project. No matter how complex or sophisticated the system, we can help you protect, simplify, and control it.

Products and Service You Can Rely On

SEL products are designed and manufactured for the world’s most challenging environments, exceeding all industry standards for temperature, shock, and electric stress. An optional conformal coating for circuit boards adds an extra level of protection against contaminants in extreme environments.

Every SEL product comes with a ten-year warranty—the best in the industry. If any product fails under warranty, we’ll repair or replace it for free.

Questions? Contact Us!

If you have any questions about SEL products, services, solutions, or support, please contact us. Our service and support professionals are ready to provide the answers you need.

Unbeatable Support

SEL support teams are stationed in regional offices around the world and staffed with application engineers who are experts in our products and in power system applications.

Technical support for SEL-manufactured devices is always free. No matter how often you need to call or how long your SEL products have been in service, you’ll reach an SEL expert who can provide the service and support you need.

Our cybersecurity team is always ready with the information and resources needed to keep your OT networks and critical systems secure and working effectively. Cyber services support contracts can include incident response, audits, system hardening, and more, depending on your anticipated needs.

More about SEL warranty and support