IEEE C37.105-2024

IEEE C37.105-2024 is the standard for qualifying Class 1E protective relays and auxiliaries used in nuclear power generating stations and nuclear facilities. It addresses the technical basis for determining whether these safety-related devices can perform as intended in demanding nuclear service conditions. For engineers, procurement teams, and compliance reviewers, it helps define a consistent path for evaluating relay and auxiliary equipment where dependable protection and controlled response are critical to plant safety and operational continuity.

Overview of IEEE C37.105-2024

This technical document focuses on the qualification of Class 1E protective relays and auxiliary equipment within nuclear engineering applications. IEEE C37.105-2024 is relevant where electrical protection devices must support safety functions and remain reliable under the environmental and operational conditions associated with nuclear facilities. The standard is useful when assessing design, testing, and acceptance criteria for equipment intended to serve in safety-related power and control systems, helping align technical expectations across vendors, operators, and reviewers.

Typical use cases

IEEE C37.105-2024 is typically referenced for protective relay qualification in nuclear power generating stations, balance-of-plant safety circuits, and related auxiliary equipment assemblies. It may be used when specifying or reviewing devices that participate in Class 1E electrical protection schemes, including relays tied to shutdown logic, trip functions, or other safety-significant control paths. The standard can also support procurement and qualification planning for new equipment, replacements, or upgrades in nuclear facilities.

Why it matters

In nuclear applications, protective relays and auxiliaries must be evaluated with care because their performance can affect safety, equipment protection, and regulatory confidence. IEEE C37.105-2024 helps provide a common framework for qualification, reducing ambiguity during design review and testing. Using a recognized standard can improve consistency across projects, support compliance documentation, and lower the risk of selecting devices that are not suited to the intended Class 1E service environment.

• Class 1E protective relay qualification
• Nuclear power and nuclear facility applications
• Auxiliary equipment for safety-related circuits
• Design, testing, and acceptance planning