Intro to Relays #3 – What does SEL stand for?

Protective relays represent a sophisticated aspect of electrical engineering and contracting, often perceived as daunting. However, they don’t need to be intimidating! This series of three articles aims to introduce the basics of relaying to those outside the engineering field, particularly in the solar and energy storage sectors. --- **Intro to Relays #1 – What Are Relays, CTs, & PTs?** **Intro to Relays #2 – ANSI/IEEE Relay Device Numbers** **Intro to Relays #3 – What Does SEL Stand For? (Below on This Page)** --- **What Does SEL Stand For?** If you find yourself in a conversation about protective relaying, chances are you’ll hear the term “SEL” crop up frequently—almost every third sentence. **The Company Name** SEL stands for Schweitzer Engineering Laboratories. As the leading manufacturer of utility-grade relays and other protection, monitoring, and control devices, SEL is a household name within the electrical industry. If you’re working on a solar or energy storage project involving relays, there’s a good chance you’re dealing with a Schweitzer product.  Other popular relay manufacturers in the solar space include GE, Basler, and Beckwith. While these brands are well-regarded, we encounter and utilize SEL products far more often than any of the others combined. --- **Model Numbers** The term "SEL" also appears in their model numbers, making it easy to identify both the manufacturer and the specific model in a concise format. All of Schweitzer's relays begin with "SEL-" followed by three digits and occasionally a letter. Here are some common models: - **SEL-751**: Feeder protection relay (the most frequently used by Pure Power), though it serves purposes beyond just feeder protection. - **SEL-351**: Protection system relay. - **SEL-551**: Overcurrent relay. - **SEL-587**: Overcurrent differential relay. - **SEL-651R**: Recloser control. ---  Schweitzer Engineering Laboratories offers more than just protective relays. Their product lineup includes: - **SEL-735**: Power quality and revenue meter (perfect when you need a top-tier meter paired with your relay). - **SEL-3530**: Real-Time Automation Controller (RTAC). Pure Power uses this RTAC for dynamic control and curtailment of solar systems. --- **Conclusion** At its core, understanding relay device numbers is straightforward. Yet, as you dive deeper into the subject, complexity grows rapidly. Developers and project managers don’t need to become relay experts—they just need Pure Power on the job. Our seasoned team of engineers ensures that your relays are designed, fabricated, programmed, and commissioned efficiently and cost-effectively. If you require assistance with the relays on your project, click [here](#) to learn more or contact us today at [your-email@example.com]. --- **Attention Engineers!** If you’re passionate about technical topics like this one, you might be a great fit for Pure Power! Our team of 80 engineers designs over 2,000 commercial and industrial (C&I) and utility-scale solar projects annually. Surrounding yourself with such expertise can significantly elevate your career trajectory. Explore our open positions [here](#). --- This introduction should provide a solid foundation for understanding protective relays, CTs, PTs, and the role of SEL in the industry. Stay tuned for further insights in upcoming articles!

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