IEEE PC37.109/D3.5, August 2023 is a draft guide focused on the protection of shunt reactors in power systems. It addresses the technical considerations involved in protecting reactor equipment that supports voltage control and reactive power management in energy networks. For engineers and specifiers working in power, energy, and industry applications, this document can help clarify expected protection practices, coordination issues, and design choices relevant to reliable reactor operation.

About IEEE PC37.109/D3.5, August 2023

This draft guide is part of the IEEE PC37.109 series and is centered on protection methods for shunt reactors used in electrical power systems. IEEE PC37.109/D3.5, August 2023 is intended to provide technical direction on how these devices may be protected against faults, abnormal operating conditions, and damage risks. It is most useful where system stability, equipment longevity, and protection coordination need to be considered together during engineering and specification work.

Where is IEEE PC37.109/D3.5, August 2023 used?

This standard is typically relevant in substations, transmission networks, and other high-voltage installations where shunt reactors are used to manage line charging and voltage rise. IEEE PC37.109/D3.5, August 2023 may be applied by protection engineers, utility designers, and equipment specifiers working on reactor bays, relay settings, and associated switching arrangements. It is also useful in procurement and project documentation when shunt reactor protection requirements need to be defined clearly for power system installations.

Importance in practice

Proper protection guidance matters because shunt reactors operate in critical network roles and can be exposed to faults, overloading, and switching stresses. IEEE PC37.109/D3.5, August 2023 supports more consistent engineering decisions for protection design, testing, and coordination, which can reduce the risk of equipment damage and service interruptions. For organizations responsible for specification or compliance, it helps provide a more stable basis for design review, relay application, and acceptance checks.

• Shunt reactor protection guidance
• Fault and abnormal condition considerations
• Protection coordination and relay application
• Substation and transmission use cases
• Engineering and procurement reference