GPS Time-Sync Protocols
Several protocols are used to distribute a precise time reference to intelligent electronic devices (IEDs) in automation and power system networks for 1ms accuracy or better:
- PTP (IEEE 1588)—Precision Time Protocol (PTP), defined by IEEE Std 1588-2008, is used for hi-res time sync over an Ethernet network. [ More ]
- IRIG-B—Time codes originally developed by the US military and widely used by electric utilities and others.
[ More ]
- DCF77—Time-sync standard distributed at 24Vdc well-suited for distribution over longer distances and to large numbers of devices. [ More ]
GPS Time Synchronization
Reliable Power Starts with Precision Timing. What good are embedded clocks in power system devices if they don't know the correct time? Precision timing is required for monitoring and control of electrical power systems where power reliability is important. Circuit breaker control schemes require precise timing to ensure proper operation, and Sequence of Events Recording (SER) systems report events with one-millisecond time-stamps to aid diagnostics and troubleshooting.
For More Info:
IntroductionPoster: Time Sync via PTP (IEEE 1588)
DataSheet: Time Sync via PTP (IEEE 1588)
Presentation: PTP-Enabled SER
Tech Notes (White Papers)Tech Note: Hi-Res Time-Sync via PTP (1588)
Tech Note: SER System Architectures
Tech Note: IRIG-B Overview
Tech Note: DCF77 Overview
Tech Note: 1per10 Overview
Tech Note: STRs Can Share a GPS Antenna
Related LinksLink: GPS Time Sync Blog
GPS Time Sync Article (EC&M)
Global Positioning Systems (GPS) are used to provide a precise time reference for power system devices in an electrical network, ensuring time synchronization even across great distances. Typical “critical power” examples include electric utility networks, data centers, hospitals, water treatment plants, refineries, and other process industries.
A GPS antenna receives a time signal from a system of satellites orbiting the Earth, and a receiver converts it to one or more time protocols. Each power system device accepts a sync pulse, usually via a dedicated, high-speed digital input. The device then sets its internal clock by decoding the supported time protocol.
GPS time sync is especially useful when power system devices are located in different locations, such as buildings in a campus arrangement or multiple substations separated by great distances.