IEEE PC37.110/D4, June 2022 is a draft guide for applying current transformers used in protective relaying purposes, with attention to how CT characteristics support accurate sensing and dependable relay operation. This standard is relevant where current transformer selection, burden, accuracy, and transient behavior affect protection performance in power systems. For engineers and purchasers, IEEE PC37.110/D4, June 2022 helps define a technical basis for evaluating CT suitability in relaying applications and reducing avoidable measurement errors.

About IEEE PC37.110/D4, June 2022

This draft guide addresses the practical application of current transformers in protective relaying circuits, where correct CT performance is critical to system protection. It provides a focused technical framework for understanding how CT ratings and operating conditions can influence relay inputs, especially under fault conditions. IEEE PC37.110/D4, June 2022 is useful when reviewing design choices, comparing equipment, or checking whether a CT is appropriate for a specific relaying duty in electrical power applications.

Where is IEEE PC37.110/D4, June 2022 used?

This guide is typically used in power-system protection work involving substations, switchgear, and other installations that rely on current transformers to feed protective relays. It is most relevant in utility, industrial power, and energy distribution settings where CTs must perform reliably during normal load and fault events. IEEE PC37.110/D4, June 2022 supports engineers, specifiers, and test personnel who need to align CT application with relay requirements and expected operating conditions.

Importance in practice

In practice, the value of IEEE PC37.110/D4, June 2022 lies in helping reduce protection errors caused by inappropriate CT application. A well-matched current transformer supports consistent relay response, better fault detection, and fewer nuisance trips or missed operations. The guide can also improve procurement and design review by giving teams a common technical reference for CT selection, accuracy considerations, and application limits. That makes it useful for quality control and risk reduction in protection schemes.

• Current transformer application for protective relaying
• CT burden and accuracy considerations
• Fault-condition performance review
• Substation and switchgear protection use
• Design and procurement reference for relaying systems