This standard specifies an extended profile for the use of IEEE Std 1588-20081 in power system protection, control, automation, and data communication applications utilizing an Ethernet communications architecture. The profile specifies a well-defined subset of IEEE 1588 mechanisms and settings aimed at enabling device interoperability, robust response to network failures, and deterministic control of delivered time quality. It is compliant with IEC/IEEE 61850-9-3:2016, which specifies the preferred physical layer, Ethernet; the higher level protocol used for message exchange, Precision Time Protocol (PTP); and the PTP protocol configuration parameters. Special attention is given to ensuring consistent and reliable time distribution within substations, between substations, and across wide geographic areas. As such, this profile extends IEC/IEEE 61850-9-3:2016 with continuous monitoring of time inaccuracy, and optionally local time based on Coordinated Universal Time (UTC).