Emerson Exchange 365

Is there a standard, industry reference or best practice to determine operator workload and staff requirement for DCS consoles?

Hello. I'm happy to be here in these forums where I've found many answers and so much help most of the time without even having to formulate questions (Someone always had the same problem or one very similar and the community always gave wonderful answers that also worked for me!).

I've been dealing with a question from our management for some time: we fear that in some scenarios we have our console operators dealing with too much going on at the same time; too much loops and variables to monitor, and everything that comes with them: alarms, trends, changing setpoints, etc, so we wonder if we have staff available for our current system size in a reasonable proportion.

I really don't know how to calculate the amount of required console operators, but I can presume that it should be based in workload criteria like number of tags, loops and control, system health (including alarm system health). I can also presume that this calculation would be probably linked to the quantity of workstations and also probably to ergonomics. Our problem is that we don't really know a standard, industry reference or best practice for process industries (We are a refinery) that would guide us through this.

Anyone sharing thoughts and/or experience around this topic?

Thanks in advance.

• system size
• Delta V management
• console operators
• Staff

DXSANCH

• 29 Jun 2018 5:37 PM
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5 Replies

• meradi

  

  • 29 Jun 2018 5:53 PM

  Thank you so much for this question.  I need the same answers as we are evaluating the same thing as we bring new equipment into our main control room.  I was Googling this the other day and saw one small mention to 200 loops with a maximum of 280.  But is this only control loops, not indication/alarm tags?  What about discrete control?  What about graphics? And I agree with the other considerations you mentioned.  Since Emerson is part of the Center for Operator Performance, perhaps there is some information developed there that can be shared?

   

  Thanks to everyone that contributes!

   

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• Rachelle McWright

  

  • 29 Jun 2018 6:40 PM

  We're so happy to hear you find the Emerson Exchange 365 community a valuable problem-solving resource, DXSANCH. Please let us know how we can continue to help you on your automation journey.

  Best Regards,

  Rachelle McWright: Business Development Manager, Dynamic Simulation: U.S. Gulf Coast

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• DeltaVFans

  

  • 17 Jul 2018 11:08 PM

  In reply to meradi:

  The Center for Operator Performance has performed some research in this area. However, this is not a simple question to answer, and likely requires operations-specific operator workload analysis. Here's some background that may help help with your evaluation.
  
  Evaluating operator workload needs to include operator tasks, operator console design, alarm management, display design, control room environment, complexity of the process and the level of process automation. It also includes the operators – how experienced are they and what operator training is provided.
  
  In the mid-2000’s, the rule of thumb used was around 200 loops. However, if there is no documentation on the basis for this 200 loops target. Here it is mentioned in this 2005 Chemical Processing article:
  “generally accepted that a console operator could handle about 200 control loops, with an upper limit of around 280 loops. Interestingly, it’s difficult to find the origin of this rule…” www.chemicalprocessing.com/.../
  
  You ask what is meant by ‘a loop’. Specifically, what is the assumption about the amount of other signals being monitored and controlled (e.g. AI’s, pumps, motors, etc.) for each loop counted. I believe that a good 'rule of thumb' is typically about 10 DST’s per loop. This varies by application, with increased DST’s per loop for monitoring-intensive applications.
  
  Well managed alarms, task-based display design and display navigation, along with improved process automation can all increase how many loops an operator can handle. However, while each aspect of the operations environment affects operator performance, it is difficult to separately quantify them. For example, well designed operator displays may have little impact on operator productivity in a control room with high rates of alarm activity or many other distractions.
  
  Determining the ‘right’ number of console operators requires a good understanding of the process, expected level of automation and knowing the operators’ role. It is important to understand the tasks operators are expected to make during normal operation, as well as those expected to bring the process back under control during upsets. For example, can a problem in one area quickly propagate throughout the plant, or escalate? In this case, there must be 'on hand' enough operators to operate the integrated units during a major problem.
  
  For less integrated plants, process upsets are likely to have less of a determining factor on number of operators required, as the process upsets are more localized. This means that it is less likely that several units will have problems simultaneously and other control room operators can help share the task of returning the process to normal.
  
  Non-automation tasks (e.g. filling reports, taking samples, running lab analysis) also need to be taken into consideration. While these tasks are in both batch and continuous applications, their impact on the operator workload can be significantly different.

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• meradi

  

  • 18 Jul 2018 2:53 PM

  Thank you for a very nice summary.  This is what I needed – the most recent ideas on the subject.  This gives me talking points for the further discussion we will have to have.  But I needed to be sure I was not missing other information out there.  I had found the 2005 Chemical Processing article and not found anything else definitive.  I figured that the Center for Operator Performance was the best way to get information.

   

  Maureen Radi

  Control/Process - Tuscola

   

  Equistar Chemicals

  625 East U.S. Highway 36

  Tuscola, IL  61953

  Office: +1 217.253.1270

  Mobile: +1 217-369-3536

   

  Maureen.Radi@lyondellbasell.com

  www.lyondellbasell.com

   

  

   

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• DXSANCH

  

  • 30 Aug 2018 5:59 PM

  In reply to DeltaVFans:

  Many thanks for your reply. As Maureen already side, it is a very nice summary and certainly provides a very useful overview about the topic.

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