Not all alarms carry same weight, and not everyone should receive alarms.

By: Allan Evora & Adam Baker
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Unfortunately, SCADA alarm handling systems don’t always get the design attention they deserve. It’s imperative that both control systems integrators and SCADA end users both understand the importance of proper alarm management. With today’s shrinking O&M budgets, managing by exception makes alarm handling one of the most important functions in a SCADA system. If it is designed properly, it can make your life easier. If done poorly or left to chance, you can put your facility at risk and even decrease employee morale.

In part 1, we talked about the difference between events and alarms. In part 2, we’ll be discussing the importance of prioritizing alarms and using alarm groups.

 

Alarm Priority

All actionable conditions warrant attention, but some carry more weight than others. To efficiently manage alarms, your SCADA system needs an alarm priority scheme.

All prioritized alarms should first be based on safety, and then on potential economic impact. For example, if you know the generator starter battery is low at a medical campus central energy plant, that’s a high priority item. Why? If you need to rely on emergency power and can’t start the generator, that’s a gigantic safety issue for patients depending on electrically powered equipment to survive.

But it’s not as black and white as high vs. low priority. Based on the number of critical alarms at any given time, one alarm could be considered a higher priority than another high-level alarm. At a solar energy plant, for example, a substation trip is a higher priority alarm than a malfunctioning inverter. However, a malfunctioning inverter is a higher priority than one tracker actuator not moving.

To keep more important alarms top-of-mind, higher priority alarms should always be the most visible alarm conditions in your HMI. By developing an alarm priority scheme aligned with the expected service levels, operators are not required to decide what is most important. The SCADA system will do it for them.

 

Coordination of Alarms

Two main problems occur when a SCADA system is designed without coordinating alarms: 1) excessive alarms and 2) increased O&M costs.

Some alarms or conditions in a system will trigger multiple alarms. A circuit breaker that trips or a power supply that fails may trigger a series of alarms related to a loss of power, such as device communication failure. If the system is configured to automatically notify support personnel via a CMMS or alarm notification system, multiple support personnel may be dispatched simultaneously.

Under the prior scenario, dispatching a network technician would be a waste of time since the communication failure had nothing to do with the network or communication equipment. Most modern SCADA systems have advanced alarm handling capabilities that allow sophisticated logic to be applied to evaluating alarm conditions. By coordinating alarms, O&M costs are reduced and excessive alarm conditions are avoided that can lead to operator alarm apathy.

 

Use Alarm Suppression to Remove the Noise

Alarm suppression is a very powerful but underutilized tool in many SCADA systems. Common scenarios where alarm suppression can come in handy include:

  • An instrument out of calibration
  • Maintenance or testing conducted on equipment
  • A change in operating conditions

All these conditions could result in alarms that an operator has no ability to fix. Not only that, these conditions could lead to equipment going into and out of alarms repeatedly.

The ability to suppress alarms either proactively or in reaction to a specific condition can greatly reduce the amount of nuisance alarms in a system. This means less operator frustration and minimized risk of missing “real” alarms.

Exercise caution with alarm suppression. An audit trail should be developed in which every suppressed alarm should log the operator who placed the alarm into suppression. Time limits should be set for the duration an alarm is allowed to be suppressed. If alarms are allowed to be suppressed indefinitely, I recommend an automatic daily report distributed to facility managers.

 

Only Send Alarms to Pertinent People/Groups

Because your staff isn’t trained across all the systems in your environment, it doesn’t make sense to notify all of them for each alarm. Alerts should only be sent to the group of individuals that can provide the corrective action to fix the condition that created the alarm.

For example, in an energy plant, you might want to create three alarm groups:

  1. Chiller plant
  2. Boiler plant
  3. Emergency power supply system

If an alarm goes off for the emergency power system group, it will be sent to electricians (not mechanics). And vice versa for chiller and boiler plants.

Today’s alarm handling systems have the ability to send alarms via text message, email and phone call. Not only can internal personnel be notified of alarm conditions, but third-party service providers can also be notified to respond.

Alarm handling systems can be set up to develop the appropriate sequence and associated escalation routine for notification of support personnel. For example, if a generator fails to start, the system will note the day and time and determine if it needs to notify the electrician on duty. If it’s after hours, built in intelligence can tell the system to send a text to the on-call technician. If there is no response or acknowledgement of the alarm after a period of time, the system can then send a notification to the generator service provider.

An alarm management system that implements priorities, coordination, and groups provides owners and operators with an effective tool to keep facilities and assets running effectively, reliably, and safely.

Stay tuned for Smart SCADA Alarm Management Part 3: Best Practices