The following tip is from the ISA book by Greg McMillan and Hunter Vegas titled 101 Tips for a Successful Automation Career, inspired by the ISA Mentor Program. This is Tip #29, and was written by Hunter.
Project management is really just risk management, and a large source of risk to an automation project is the control panels. If these panels and the software can been fully tested before the team arrives on site, the only remaining unknown will be the field wiring. Here are some tricks to make sure your panels are ready to go.
Concept: A poorly designed or fabricated control panel can bring a retrofit project schedule to its knees during a start-up. Take the time to ensure that the panels are thoroughly tested and ready to go in advance.
Details: Most system integrators push the client to let them design and fabricate the panels at their shop so they know they can be thoroughly tested before arriving on site. A client is wise to agree to this arrangement, provided they are allowed to take part in the panel checkout and that the checkout occurs PRIOR to shipping the panels on site. This timing is important because if any problems are encountered during the checkout (wrong type or missing panel components, design problems, etc.), the client can get them resolved BEFORE the panels arrive on site. If the client does not get to review the panels in advance and problems are discovered after the panels are shipped, the client does not have much time to fix them and his negotiating position will be considerably weaker.
Here are some tips to consider when doing a panel test:
Watch-Outs: Do not make the mistake of shipping a panel to the plant site with the fuses still in it. The electricians will hook up the power and will want to “smoke test” the system to make sure it works. If the power is hooked up incorrectly, they WILL smoke test the system, destroy several components, and then deny it ever happened. Or they will power up the system and proceed to blow every single I/O fuse as they pull and connect wires in the field. As a minimum, pull the fuses that feed the main power supplies and I/O power. If power is put on the system, it cannot get far enough to do much damage.
Exceptions: In some retrofit projects, there are existing cabinets that must be gutted and have the internals refitted with the new system. In this case, prefab the panels as much as possible, and size them to fit inside the existing cabinets. This will still allow the team to test the panels thoroughly and the change over at start-up should proceed faster because the team is just “ripping and replacing” the internals rather than trying to install panel components during the shutdown. Be sure to measure the internal dimensions carefully, including the size of the doors. Many replacement panels have been fabricated to the wrong dimensions and would not fit in the cabinet. Still others have been fabricated to the correct dimensions, but the team failed to realize that the DOOR OPENING was smaller so they could not get the new panel through the door!
Insight: In a retrofit project, the cabinet design and the logistics of changing it out will have a huge impact on the length of shutdown required. While there is a great desire to re-use cabinet designs, realize that one size rarely fits all in system retrofits. In many cases, the cabinets and/or panels must be specially designed to accommodate the shutdown schedule dictated by the plant.
Rule of Thumb: Always take the time to thoroughly test control panels prior to shipment from the fabricator. A checkout should include pulling on each wire, performing “real world” tests of the I/O, and load testing the power supplies to make sure that everything is ready for installation. Then remove the major fuses and ship the units to the installation team.
About the Author
Gregory K. McMillan, CAP, is a retired Senior Fellow from Solutia/Monsanto where he worked in engineering technology on process control improvement. Greg was also an affiliate professor for Washington University in Saint Louis. Greg is an ISA Fellow and received the ISA Kermit Fischer Environmental Award for pH control in 1991, the Control magazine Engineer of the Year award for the process industry in 1994, was inducted into the Control magazine Process Automation Hall of Fame in 2001, was honored by InTech magazine in 2003 as one of the most influential innovators in automation, and received the ISA Life Achievement Award in 2010. Greg is the author of numerous books on process control, including Advances in Reactor Measurement and Control and Essentials of Modern Measurements and Final Elements in the Process Industry. Greg has been the monthly "Control Talk" columnist for Control magazine since 2002. Presently, Greg is a part time modeling and control consultant in Technology for Process Simulation for Emerson Automation Solutions specializing in the use of the virtual plant for exploring new opportunities. He spends most of his time writing, teaching and leading the ISA Mentor Program he founded in 2011.
Hunter Vegas, P.E., holds a B.S.E.E. degree from Tulane University and an M.B.A. from Wake Forest University. His job titles have included instrument engineer, production engineer, instrumentation group leader, principal automation engineer, and unit production manager. In 2001, he joined Avid Solutions, Inc., as an engineering manager and lead project engineer, where he works today. Hunter has executed nearly 2,000 instrumentation and control projects over his career, with budgets ranging from a few thousand to millions of dollars. He is proficient in field instrumentation sizing and selection, safety interlock design, electrical design, advanced control strategy, and numerous control system hardware and software platforms.