Monday, April 2, 2012

Operator Rounds vs. SCADA -The Cost of Adding Points to SCADA System

Plant operations professionals are routinely faced with the decision of whether to add a data point to the plant monitoring system (SCADA, BAS, etc) or add it to the Operator Rounds. For example, a manufacturing plant has been having trouble with a cooling tower pump periodically losing prime. To help troubleshoot the problem, they decide to start tracking the suction pressure of the pump. They can either add the pressure to the Operator Rounds, or add instrumentation to add it as a point to the plant SCADA system.

There are a number of factors to consider in each of these decisions. These include:

How critical is the data point?
What are the consequences if this data point goes out of spec?
Is continuous monitoring with out of spec alarming required?
Or is it a data point that if it goes out of spec for a few days will not cause costly damage?

These are very important questions and are the basis of processes like Reliability Centered Maintenance (RCM). This article does not address these questions.

This article addresses determining the cost of the SCADA vs Operator Rounds options. These decisions should always be business decisions, where a cost / benefit analysis is performed  of each option then used to help select the option that is best for the plant.

It is our opinion that the costs of both of these options are routinely under-estimated. I hope this article helps you make accurate cost estimates that are useful in making the right decision.
What Goes Into the Cost of Adding a New Point to SCADA System

For this example we will be adding a pressure sensor to the suction side of the cooling tower pump. Our plant uses a SCADA system to monitor critical system. Field devices send their signals back to the SCADA server using a plant Ethernet system. The following are items that may go into the cost of installing a new data point to a SCADA system:
  1. Cost of the measurement device. In this example we are adding an pressure transmitter ($350 - $3,000 depending on your plants requirements).
  2. Wire and conduit to get the signal from the measuring device to the sending device ($200 to $500).
  3. Power wiring for the measuring device (if needed) ($200 - $500)
  4. Cost of the sending device (if needed). If we have a PLC nearby with an available I/O then we are in luck. If not we will need to add either a PLC ($1500) or Remote I/O module with Ethernet connection($300).
  5. Wire and conduit to get from sending device to Ethernet drop (if needed). ($800 - $1500)
  6. Power wiring for the measuring device (if needed) ($200 - $500)
  7. Configure new data point in SCADA system. Assume it will take in house person 1 hour (if you have one) to add the point and configure the low and high limits ($50), contractor ($250).
  8. Add new data point to graphic screen in SCADA system. Again in house ($50), contractor ($250).
  9. Miscellaneous engineering costs. Include 4-6 hours for selecting and procuring  the correct measurement device, selecting and procuring the correct sending device, routing power and communication wiring, establishing high and low limits and implementing response protocols. ($300)
The costs quoted above are very rough estimates. Actual costs will vary at each plant. But at the very least, each of those items listed should be considered when calculating your costs for adding a point to a SCADA system.

What Goes Into the Cost of Adding a New Point to Operator Rounds

There are costs associated with adding a data point to Operators Rounds. This is true whether your operators use a clipboard and pencil or handheld data collection software like FDPMobile(http://tinyurl.com/3qykyvb) to record their readings.

 These costs include:

  1. Add new data point to paper log sheet or to handheld data collection software like FDPMobile. Assume it will take an in house person 1 hour to setup the new point and, if using paper log sheets, publish the new log sheet ($50).
  2. Operator labor time required to collect the data. This cost can vary greatly depending on frequency of data collection and location. If you can add the reading to an established set of Operator Rounds and the new point is along the route then you may consider the costs to be negligible. If this new data point can not be added to an existing set of Operator Rounds then you need to quantify the labor hours required to collect this data. In an extreme example, if the pressure gauge is in a confined space that requires 1.5 labor hours to do a confined space entry each time you read it, it could cost thousands of dollars per year to get this data.
Just like with the SCADA system, the cost of adding a data point to Operators Readings varies greatly depending on the application and the specific plant.

Conclusion

When plant operations professionals are deciding whether to add a data point to a SCADA system or to plant Operator Rounds installation and on-going costs should be considered.

Adding a point to a SCADA system can cost from just over $1000 to over $10,000, but with continuous monitoring and alarming capability can greatly improve the reliability of the system.

Adding a point to Operator Rounds can range in cost from $50 to several thousand dollars per year. When added to a well designed Operator Rounds program, the new data point can add to the plant operator's knowledge base and improve his or her ability to identify and correct potential problems.

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Our software solution, which includes mobile data collection software FDPMobile and web application FDP Plant, was designed by plant operators to solve some of the challenges faced daily by operators. It is designed to be complementary to any SCADA system. If you would like more information please visit us at http://www.fielddatapro.com/ or email info@fielddatapro.com .

5 comments:

  1. Hey! I will be looking forward to visit your page again and for your other posts as well. Thank you for sharing your thoughts about rcm or reliability centered maintenance. I am glad to stop by your site and know more about rcm or reliability centered maintenance. Keep it up! This is a good read. You have such an interesting and informative page.
    Reliability Centered Maintenance can be used to create a cost-effective maintenance strategy to address dominant causes of equipment failure. It is a systematic approach to defining a routine maintenance program composed of cost-effective tasks that preserve important functions.
    RCM Blitz™ founder and facilitator, Doug Plucknette, is the author of Reliability Centered Maintenance using...RCM Blitz™ as well as his latest book Clean, Green and Reliable: The Role of Maintenance in Sustainability.

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    ReplyDelete
  2. DCS networks have their limitations. They cannot cover large territories. This is where SCADA comes in handy. However the communication systems are not as reliable as a LAN, and therefore it is not viable to implement closed-loop control. Right now, the size and scope is what mark SCADA.
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  3. This is very good information.i think it's useful advice. really nice blog. keep it up!!!
    Reliability Centered Maintenance

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  4. Thank you for sharing. RCM Software allows users to identify and quantify root causes within their facilities.

    ReplyDelete