Scada system records detailed sequences

New "momentary change detection" or MCD processing in iPower Scada allows detailed analysis of sequences of events.

The electric utility's problem: high wind makes a tree branch briefly force two power lines together, causing a relay to "trip" open.

As designed, the relay immediately automatically closes, in case the trip was caused by just this type of temporary problem.

The power is restored, avoiding a significant outage.

But this close-open-close sequence can happen very quickly.

If it happens between successive polls from the central Scada, then as far as the Scada is concerned, the relay never tripped.

Scada operators running the electricity network have no idea there has been a problem.

The solution: some RTUs, especially those used in the electric power industry, can generate and store their own event records.

Called "sequence of event" (SOEs), these events have the advantage of being precisely time-stamped, usually to 1ms resolution.

Importantly events captured by an RTU include all these momentary changes that can otherwise be missed by the Scada master station.

iPower already recovers SOEs and reports them to iPower users within the iPower events list.

New "momentary change detection" or MCD processing in iPower completes the solution: MCD logic derives the occurrence of brief digital changes by examining discrepancies between SOEs and regular Scada events.

MCDs are reported in the iPower events list as a distinct "MCD" class, making it easy Scada operators to identify and report these transient changes.

In addition to MCD event recording, iPower also provides MCD alarm notification.

Standard IFix DA blocks may be configured as MCD alarms, delivering all standard alarm processing and display options.

What does it mean for the electric utility operators? That depends on the scenario, but in each case the operator gets a clearer picture of what has happened in their network.

MCD was formally released in iPower 2.40 in December 2004.

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