IEEE 1588v2

A Time Protocol for Industrial Ethernet Networks

• NTP, GPS, and IRIGB are capable technologies that simply aren’t suited for the requirements of industrial Ethernet networks. Fortunately, the IEEE 1588v2 Precision Time Protocol (PTP) is designed specifically for industrial networked measurement and control systems. In a network based on IEEE 1588v2, the grandmaster clock determines the reference time for the entire substation automation system. The Ethernet switch acts as the boundary or transparent clock, and additional devices (such as merging units, IEDs, and protection devices) are designated as ordinary clocks. All of these devices are organized into a master-slave synchronization hierarchy with the grandmaster clock at the top. As illustrated in the figure below, exchanging PTP packets between master and slave devices, and automatically adjusting the ordinary clocks, effectively synchronizes the entire network. Only the grandmaster clock needs a connection to GPS timekeeping; that data can be accurately distributed to the rest of the devices on the network.

  

  An Ethernet switch that supports IEEE 1588v2 can guarantee time-stamping accuracy to within 1 µs, and be configured for master, boundary, or transparent clock functionality. IEEE 1588v2's advantages have led to its incorporation in the IEC 61850-2 standard for electrical substation communications, which specifies communications requirements for power automation networks. The IEC incorporated IEEE 1588v2 because more precise time synchronization allows electrical substations and power automation networks to achieve the following benefits:

  Blackout prevention through early detection of grid problems,

• early location of disturbances, and real-time power islands.

  More efficient use of assets through congestion relief and equipment condition monitoring.

  The smart grid uses time-of-use billing, virtual power generators, and outage management to respond to demand. When combined with the advantage of of IEEE 1588v2's nanosecond-level accuracy, substations and other power utility networks gain a competitive edge just as formidable as the one Britain's chronometer equipped navy had over its peers.

  Benefits

  Moxa's PT-7728-PTP IEC 61850-3 Fast Ethernet switches support the latest version of IEEE 1588v2 technology to deliver precise time synchronization for electric power protection and control applications. The PT-7728-PTP offers:

  • • Up to 14 100BaseFO (Multi-mode ST connector) or 100BaseTX, ports and 1 BNC connector, support for IEEE1588 v1 and v2 hardware time stamping on each port, and pulse outputs (pps) on one BNC port.
  • • 1 and 2-step for both transparent and boundary clock operation with accuracy under 1 μs in End to End mode.
  • • 2-step for both transparent and boundary clock operation with accuracy under 1 μs in Peer to Peer mode.
  • • Network clock synchronization accuracy in the nanosecond range.
  • • Clock synchronization to support large and distributed substation networks.
  • • Low-cost implementation in multicast messaging networks such as Ethernet.
  • • Fast re-synchronization when system changes occur.
  • • Simple installation and maintenance.

• A Time Protocol for Industrial Computing Networks

  For industrial computing networks, IEEE 1588v2-compliant computers can work as ordinary clocks that connect to Ethernet switches and receive and synchronize the time. The time can even be detected at the nanosecond-level, and works well with devices on the same network, considerably enhancing the reliability requirements for power substation systems. IEEE 1588v2-compliant computers provide the following benefits.

  

  Benefits

  1. Power blackout prevention, fault recordings and event loggers.
  In power substations where time precision is crucial, computers with IEEE 1588v2 compliance are essential. This type of computer can analyze fault recordings and event loggers in a few nanoseconds, and help determine the root causes of power blackouts.

  2. Complete power automation network with IEEE 1588 protocol
  To qualify as a complete IEEE 1588v2-compliant network, the Ethernet switches, end devices, and industrial computers must all support IEEE 1588v2. In the current market, end-users who use IEEE 1588-compliant computers have a big advantage over the competition since the computers can be used with switches and IEDs for the power automation network, and can also provide accurate time synchronization.

  The Moxa Advantage

  Moxa's DA-683-LX embedded computers support the

• IEEE 1588v2 protocol to deliver precise time synchronization for substation networks and related applications. The DA-683-LX computers offer the following advantages:

  1. Low power consumption

  Moxa's DA-683 embedded computers consume only 40 watts, which is a common industrial-grade requirement. In addition, Moxa's computers use a fanless/cable-less design (i.e., an all-in-one on board) to guarantee stable system operation, but will not generate a lot of heat.

  1. IEC 61850-3 certified

  IEC 61850-3 certified products meet industrial-grade requirements for power automation by ensuring stable and reliable operation in substation networks.

  1. Modular design with great flexibility

  Moxa’s DA-683 embedded computers come with two independent slots for flexible system integration and expansion. Users have the option to add a variety of different communications modules, including an 8-port RS-232/422/485 module, 8-port RS-422/485 module, 4-port 10/100 Mbps LAN module, 8-port 10/100 Mbps switch module, and a universal PCI expansion, making the computers particularly cost-effective for system integration and expansion.

  1. User-friendly interface for IEEE 1588 configuration

  DA-683 embedded computers running the Linux operating system offer an easy-to-use user interface for IEEE 1588 configuration. IEEE 1588 time synchronization can be set up easily in only a few steps, saving time and money for system configuration and maintenance.
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