IEEE C37.105-1987

IEEE C37.105-1987 is a technical standard for qualifying Class 1E protective relays and auxiliaries used in nuclear power generating stations. It addresses the performance and qualification expectations for equipment that supports protective functions in safety-related power systems. This standard matters because dependable relay operation can help maintain consistent protection, support plant safety objectives, and reduce uncertainty during procurement, testing, and design review in nuclear applications.

IEEE C37.105-1987 overview

This standard focuses on qualifying protective relays and auxiliary devices intended for Class 1E service, where equipment reliability and suitability are especially important. IEEE C37.105-1987 provides a framework for evaluating whether these components can perform as required in the demanding conditions associated with nuclear power generating stations. For engineers, purchasers, and reviewers, it offers a clearer basis for assessing compliance, technical acceptability, and qualification evidence for safety-related control and protection equipment.

Typical use cases

This document is commonly referenced when specifying or reviewing protective relays, relay auxiliaries, and related Class 1E equipment for nuclear plant electrical systems. It may be used during design qualification, vendor evaluation, acceptance testing, or documentation checks for safety-related protection schemes. Typical applications include station protection panels, auxiliary relay assemblies, and systems where qualified performance is needed to support reliable trip, control, or isolation functions in nuclear power generating stations.

Why this standard matters

In practice, IEEE C37.105-1987 helps organizations apply consistent qualification criteria to components that play a critical role in protection and safety. Using a recognized standard can improve design control, support more reliable procurement decisions, and reduce risk tied to unverified equipment performance. It also gives buyers and engineering teams a common technical reference for testing and documentation, which is especially important when protective relays and auxiliaries must meet stringent expectations in nuclear service.

• Class 1E protective relays
• Auxiliary relay qualification
• Nuclear plant electrical protection
• Testing and acceptance criteria
• Safety-related equipment review