Maintenance Technology July 2017 - 29

AUTOMATION STRATEGIES

By avoiding alarming on events, an HMI's screen should
clear up considerably.

A properly designed SCADA
system can be a valuable,

Declutter the alarming functionality.
Operators may love SCADA, but most of them are challenged
when it comes to managing alarms. The amount and/or
frequency of alarms can create stress and ultimately result in
critical conditions being missed due to excessive alarm noise.
An effective way to minimize the alarms that an HMI
displays is to differentiate between them and events:
■ Alarms indicate an abnormal condition, e.g., leak detected,
fuel-level low. They signal a call to action for the operator.
Alarms should never confirm a normally running process.
■ Events are situations that need to be logged for future
reference, but most likely may not require operator action,
e.g., chiller started, motor running. Events should still be
logged for future analysis, but never alarmed on.
By avoiding alarming on events, an HMI should clear up
considerably. This approach also helps avoid operator apathy
(a common situation among those who have experienced too
much noise in the system for alarms to be meaningful.)
In larger systems, another effective way to reduce alarm
clutter is to use conditional alarming. Most SCADA systems
allow logic to be applied to the alarm configuration. Alarm
logic can be used to suppress children alarms when a parent
alarm occurs. For example, if putting a piece of equipment
into bypass/maintenance mode triggers certain related conditions, a decision can be made to only configure the bypass
condition as an alarm, and configure the other resulting
conditions as events.
The International Society of Automation (ISA), Research
Triangle Park, NC, has published Standard 18.2 that discusses
best practices as it relates to understanding and applying
alarm-management systems.
JULY 2017

productivity-enhancing tool.
Crafting HMIs to be intelligently obvious
Displaying data from a SCADA system on an HMI
is light-years away from past methods of monitoring critical plant systems. Instead of frantically
running around recording values on a clipboard,
personnel can calmly view an entire facility's
performance on a single screen.
In Evora's view, the effective operation and
maintenance of a site and/or process will only be
as good as the tools provided to its operators. "A
SCADA system can be a highly valuable, productivity-enhancing tool," he said, "but it must be
designed properly." Clearly, the less time operators
spend analyzing data, the more time they have to
fix the actual problems that an HMI identifies.
Evora noted that it's up to the owner/operator
to stress the importance of data efficiency to the
system integrators. "Owners should place great
emphasis on turning a screen full of data into
actionable information that's easily readable at a
glance," he concluded. "Otherwise, data efficiency
may not be a design priority." MT
A Certified Measurement & Verification Professional
(CMVP), Allan Evora has more than 20 years of
industry experience working in every capacity of
the power-automation-project lifecycle. Charlotte,
NC-based Affinity Energy (affinityenergy.com) is
a partner of AutomationDirect (automationdirect.
com, Cumming, GA).
MAINTENANCETECHNOLOGY.COM | 29

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Table of Contents for the Digital Edition of Maintenance Technology July 2017