Smarter SCADA Alarming
Practical Ideas for Effective Alarm Management
One afternoon at a waste water treatment facility, an alarm goes off when the water pressure gets too high in one of the tanks. The alarm is set at priority level 4, which means "critical," but it doesn't stand out because almost every other alarm at the facility is set at that level. Besides, the operator can't acknowledge it right away because he's dealing with several other alarms that went off a few minutes earlier – which he doesn't yet realize are just "nuisance alarms."
What's Wrong With My Alarm System?
To answer the question above, let's review some basics about alarms. There are three main events in the life cycle of an alarm: becoming active, becoming clear and being acknowledged. An alarm becomes active when the value it's attached to goes outside of its normal range, which is defined by high and low setpoints. An alarm becomes clear when a value returns to its normal range, at which point it drops out of the alarm system.