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Elmec Pty Ltd
Licensed Electrical Contractor QLD 73897
PO Box 70
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QLD, 4521
Australia
Alarm Management... What are you going to tell the Coroner?
Sunday, October 14, 2018
We've all seen it... alarm after alarm on the HMI and SCADA systems in almost every plant that ever existed.  The trouble is, once you've seen it you can't ignore it without having just assumed some responsibility for an incident or accident later on down the track that could have been prevented if you'd done something about those annoying alarms.  You think it doesn't happen?  Well think again - here's just two instances of what goes wrong:

- On May 13 2002, pilot lights on the flare system at a chemical plant were extinguished. This occurred because there were fluctuations in the gas supply to the flare. A large gas cloud formed but fortunately did not ignite. The flare gas came from an installation which was being restarted. The restart process normally produced 3,700 alarms so not surprisingly, the operators failed to detect the alarm for the flare.

- On March 28, 1979 Unit 2 of the Three Mile Island Nuclear Plant in the United States of America an incident would lead to a partial reactor core meltdown. Many blamed the operators for stopping the reactor cooling system but the real root causes showed a known flaw in the design and alarm flooding had blinded the operators to what was actually happening. Operators could not understand the exact fault due to a "lit-up" panel and took corrective actions that actually led to the incident.

Accepted standards (EEMUA191 and ISA 18.2) state that 1 alarm every 5 munites is acceptable for an operator to deal with... 'Peak' alarm rates kick in at 1 alarm per minute over a 10 minute period.  How many plants can say that their alarm performance falls in line with this? 

What we've seen in the real world is Systems Integrators / EPCM contractors leaving project after project commissioned and handed over to the client with in some cases well over 80,000 alarms per day.  This sort of thing seems to be the norm, but coming back from something like that to an acceotable level is possible.  It requires a dedicated effort from operations, maintenance, and control systems personnel and is achievable.  To not do something about an alarm(ing) situation is at best negligent.

SCADA and HMI Graphics... Why Bother?
SCADA and HMI Graphics... Why Bother?
Thursday, September 20, 2018
Here we are in 2018 and still process plant operators, maintainers, owners, and even the PLC & SCADA people who put the operator interfaces together argue... Green = running, Red = Running... and on it goes.  Nobody can agree. 

There's an ISA Standard (ISA101) which deals with the whole lifecycle of control systems but the one thing that has come out of all of this is that our HMI & SCADA Graphics standards have for years been... well, rubbish.  One of the key goals of ISA101 is to deliver a system that results in safer, more effective, and more efficient control of a process, under all operating conditions and which will improve the user’s abilities to detect, diagnose, and properly respond to abnormal situations... doesn't sound too hard does it?

One of the outcomes of the whole process is graphics standards which on the surface look boring and disinteresting (can you say greyscale?)... and that's the whole point up until there's a problem in the process.  That's when the correct use of colour makes a difference with studies showing that operators are less likely to miss a problem with a well thought out greyscale HMI as opposed to the traditional HMI which looked like a mad piece of modern art. 

Operators do 'miss stuff' when they're busy or just plain fatigued..  A quick story... about 18 years ago a process plant bogged their tailings thickener on nightshift... 23:45pm to be exact.  If you don't know processing, bogging a tails thickener is a big deal.  The operators blamed the SCADA and the PLC techs and 'the system' which gave no warnings (it did), and swore that the tails thickener page was always displayed and they always watched it.  To prove a point the PLC techs put a shark (we'll call him Bruce) in the thickener... Bruce did laps from 23:00 to midnight and then disappeared.  It took 3 months for the control room operators to notice Bruce so I guess you could say that the operators weren't doing what they said they did (watching the thickener at all times).  In reality, they shouldn't have to sit with their eyes glued to something, - if there's a problem it should stick out like a sore thumb, and that is what the whole ISA101 / greyscale thing is about...

Mine Site Recommissioning
Wednesday, August 01, 2018
This last week we've looked at another processing plant for a client with a view to recommissioning.. it's an old one and it has had more than a few 're-starts' over the years. 

The interesting thing is that it's one where we've  been many years ago and you can't help but look around at the changes..  The township, concentrator, power station, and most buildings are mostly all demolished and removed and the bush has taken over.  The plant itself has been left to it's own devices for over a decade but despite that  it's looking like a fair percentage of the hardware has survived due (mostly) to the low humidity of the location. 

There's still plenty of work that will need doing in order to make things work again, but in this case Mother Nature has been kind.  This isn't always the case and the best thing that any owner of a plant that's closing down can do is to prepare it properly for closure... chances are it's going to be re-started by someone one day or sold on, and the time and effort put in to a decent closure strategy will be repaid many times over.  Here's a decent article on what needs doing:

https://www.reliableplant.com/Read/28796/do-before-plant-closure

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