html{display:none} Quality Philosophy | Schweitzer Engineering Laboratories

Quality Philosophy

Quality Philosophy

Integrating simplicity and innovation into every process.

Manufacturing 201906

Dr. Edmund O. Schweitzer, III, the founder of SEL, taught his first employees that they all “owned quality.” Today, we continue to embrace this principle—that quality assurance is a collective responsibility and every employee plays a critical role.

We recognize that quality isn’t determined by any one department—it’s the result of diligent efforts and continuous innovation throughout the entire company. Guided by the principles of World Class Manufacturing and our company values, our employees continually strive to simplify and improve our processes at every level—from design and manufacturing to testing and customer support.

Quality Highlights

"SEL designs, tests, and builds products to the highest quality standards. We empower our employees to take ownership of quality, find the root cause of every problem, and continuously improve processes."
Adrian P. C. Genz, Quality Director


"All of our work in Research & Development is based on the first principles of engineering. Everything we do should be solving a problem for our customers. We’re constantly asking ourselves, 'How can we improve our designs to add value for our customers?'”
—Ryan Bradetich, Senior Vice President of Research & Development

The SEL design process is best summarized by our quality policy: “Understand. Create. Simplify.” The process always begins with our customers as we work to understand their needs and challenges. Driven by these considerations, we create effective solutions using the simplest designs possible—because we believe simplicity is the key to producing efficient, reliable technology.

All our products are designed to operate reliably for over 20 years, even in the most challenging environments. Using robust, type-tested designs, we create devices that can withstand extreme temperatures, corrosive agents, electrical surges, and other harsh conditions—consistently exceeding the highest industry standards for durability and performance.


“We manage and maintain a robust supply chain, put every product through rigorous testing, and strive to shorten feedback loops so that mistakes are caught and fixed quickly. That’s how we ensure quality in Manufacturing.”
—Leith Sorenson, Senior Vice President of Manufacturing

SEL carefully manages every aspect of manufacturing to ensure consistent quality across all our products. We manufacture all electronics at advanced facilities in the USA, which are certified to the most recent ISO 9001 standard for quality management systems. In addition, our assemblers are trained to meet the strict requirements of IPC-A-610 Class 3—the performance standard required for critical military, aerospace, and medical electronics.

We also manufacture an increasing number of our own components, including plastics, transformers, metal cabinets, and test switches. This vertical integration allows us to have greater control over the cost, lead time, and quality of our products. Meanwhile, we ensure the quality of our other materials by carefully evaluating every supplier, auditing their facilities and processes, and continuously testing the integrity of their components.


“We test to see where the devices will actually break down, so that we don’t only meet the specifications, but we exceed them. That’s why people choose an SEL relay over any of the others—the peace of mind that comes with it.”
—Normann Fischer, Vice President of Research and Development

Throughout the design and manufacturing processes, SEL conducts several rounds of testing to guarantee the reliability of every product. We perform these tests at our onsite R&D and compliance test laboratories, which are accredited to the latest ISO/IEC 17025 standard. By operating our own facilities, we’re able to test our devices more often and more rigorously—ensuring that they meet not only the industry regulations but also the stringent standards we set for ourselves.

During type testing, new products are subjected to a range of high-stress conditions to establish and confirm their operating limits. These products also undergo extensive hardware-in-the-loop testing at our Real-Time Digital Simulator (RTDS) facility, which allows us to assess their performance in hundreds of real-world scenarios. After products are qualified for manufacturing, we continue to verify their quality every day by performing functional and environmental tests on each individual unit.

Ongoing Support

"At SEL, we provide unmatched quality through our technical support and customer service. In the rare event that an SEL product fails, we work with customers to not only fix the problem fast, but also learn from the incident so we can continue to improve our products year after year."
—David Costello, Chief Sales and Services Officer

We demonstrate our confidence in the quality of our products with a worldwide, ten-year warranty—the most comprehensive in the industry. This warranty offers assurance to our customers and encourages them to return their products for free repairs—giving us the valuable opportunity to learn from each product malfunction and failure.

Returned products are examined and repaired by technicians at the SEL Product Hospital, typically within 72 hours of arrival. During this process, our technicians perform thorough analyses to determine the root cause of each failure so they can track recurring issues and develop comprehensive solutions.

We use the data from these analyses to continuously improve product designs, refine manufacturing processes, and calculate meaningful reliability metrics. Rather than relying on predictive models, we base our metrics on actual field performance—providing a more accurate insight into the quality and reliability of each product.

SEL System and Product Certifications

The quality, safety, information security, and environmental management systems that underpin SEL research, development, manufacturing, laboratory, and corporate environments are certified to internationally recognized standards by the British Standards Institution (BSI) and the American Association for Laboratory Accreditation (A2LA).

SEL also works with accredited certification bodies to obtain the product certifications that are necessary for our customers, who operate in a variety of industries and regulatory environments around the world.