OFS system time stamping

Power Operation provides the System Time Stamping method for the electrical distribution monitoring and control system.

System Time Stamping helps the user analyze the source of abnormal behaviors in an automation system.

The benefits of the system time stamping mode are:

  • No PAC programming required: All the time stamped events are managed and transferred automatically by OFS
  • Direct communication between the time stamping modules and the client: The available communication bandwidth in the PAC is preserved
  • Advanced diagnostic functions:
    • Signaling of uncertain SOE (sequence during which some events may be lost) to the client
    • Time quality information is associated with each time stamped event
  • No loss of events in normal operating conditions:
    • An event buffer stores the events in each event source module. The event buffer behavior is configurable
    • Both rising and falling edge transitions can be stored for both discrete I/O and PAC internal variables
  • Works with both a redundant hot-standby PAC and redundant SCADA

The current limitations of the system time stamping are:

  • A communication path between OFS and the time stamping sources is required, so, routing is necessary in multi-layer architectures.
  • 2 OPC servers (running for HMI and SCADA) cannot simultaneously access the same time stamping source. A reservation mechanism is implemented.
  • No detection of transition edges; the event detection is processed only on both edges.

The following table describes the main features:

Process

System Time Stamping

1. Synchronize the time clock

ERT module is synchronized by IRIG-B/DCF77 link and x80CRA and M580 CPU are synchronized by the NTP server

2. Time stamping of events generation

I/O events are stamped by x80 ERT modules and CRA

Internal variable values are stamped by the M580 CPU

3. Manage the time stamped events in PAC buffer

Events are managed and transferred to Power Operation automatically by OFS

4. Transfer time stamped events from PAC to SCADA

Events are managed and transferred to Power Operation automatically by OFS