“Know your enemy and know yourself, and you can fight a hundred battles without disaster.”
- Sun Tzu (Chinese general and military strategist, c. 6th Century BCE)
An
alarm that annunciates excessively, unnecessarily, or does not return to normal
after the correct response is taken.
Let’s
dig deeper to know more about these bad actors that make the job of your
operators so stressful.
Frequent
Alarms: These are alarms that
occur quite often. If there are too many frequent alarms in your system, it
means either there is something wrong with the facility or the alarm limits you
have set. Eliminating the top 10 or 20 of these alarms can help reduce the
alarm load significantly. Hence it becomes important to review the most
frequent alarms on a daily, weekly or monthly basis.
Chattering
Alarm: A typical chattering
alarm transitions repeatedly between ON (alarm) and OFF (normal) state in a
short period of time. These alarms cause a lot of noise in the system and are
the main culprits responsible for operator distraction.
Fleeting
Alarms: A fleeting alarm is a
type of nuisance alarms that appears and disappears frequently. These alarms
are of very short duration, usually too short for the operator to act upon.
Unlike a chattering alarm, fleeting alarm does not repeat immediately and this
is the main difference between these two alarms.
Standing
Alarms: These alarms remain
in active alarm state for very long durations even after being acknowledged,
sometimes lasting longer than 24 hours. Standing alarms often indicate
conditions caused by faulty alarm limits and equipment that might be offline or
out of service. These alarms clutter the alarm displays and are a source of
continuous distraction to the operator.
Consequential
or Cascading Alarms: These are the alarms
that are triggered as a result of some other alarm. Technically these alarms do
not fall under “nuisance alarms” category; however, these can contribute
significantly toward alarm overload. Consequential alarms over a very short
period of time often lead to a condition called ‘alarm flood’, which can in
turn result in a situation where the operator or engineer would not be able to
identify true root causes or problem areas.
Redundant
Alarms: Alarms that inform
about the same action. Redundant sensors, equipment or instrumentation are the
reasons behind these alarms. Alarm shelving is the commonly used alarming
technique to manage these alarms.
 |
| Get your Copy! |
An alarm system is like a silent guardian keeping a watch over your plant’s processes, equipment and personnel, and effectively alerting control room operators in case of anomalies and abnormal situations. Identifying and eliminating nuisance alarms is one of the most important aspects of effective alarm management. It can help reduce noise in the control room, improve operator efficiency and facilitate smooth run of your plant processes. Alarm management tools like Wonderware Alarm Adviser can be quite helpful here; visit www.alarmadviser.com and see yourself how this brand new alarm analysis software can help you discover the villains of your SCADA alarm system. Remember, ignorance is the most dangerous enemy. Whether it is a battlefield or a manufacturing facility, knowing the enemy is the first step toward winning.
Nuisance
alarm elimination is just one part of a much broader alarm management strategy.
Alarm rationalization and auditing are other activities that are equally
important. In the future blogs we will talk about rationalization, advanced
alarming and industry standards on alarm management.
Special thanks to Suman Singh (sumankumar.singh@schneider-electric.com) who contributed to this article.
Take a peek at the sample of The Wonderware OEM
Post and make sure
to subscribe to get regular editions delivered to your inbox.
No comments:
Post a Comment