The design, installation, and monitoring of time synchronization systems in power utility substations is covered. This includes time sources such as Global Positioning Satellite (GPS) and time distribution systems such as Inter-Range Instrumentation Group Format B (IRIG-B), Network Time Protocol (NTP) or Simple Network Time Protocol (SNTP), and IEEE Std C37.238™. The time source and the intelligent electronic device (IED) are assumed to have accurate clocks.