Analysis of Automation System Modernization Alternatives

Emerson’s Gordon Lawther, an automation system modernization specialist, will be presenting at this year’s Emerson Exchange. His presentation, Total Installed and Commissioned Cost Savings using Electronic Marshalling in Brownfield Modernization Projects pretty much sums up its focus.

Gordon cites a recent ARC Advisory Group study that estimates $53 billion USD in installed control systems that have been in operation for more than 20 years. If you consider the technology changes in your personal life in the last twenty years, you’ll appreciate the advancements in system capabilities.

Gordon and the modernization team performed an analysis for a specialty chemical process manufacturer seeking to replace a 20+ year old system. The objective of the analysis was to consider the total installed and commissioned cost including the control system equipment, front-end engineering design, electrical and instrumentation (E&I) design engineering, control system configuration, training, installation, cutover and commissioning, startup, freight, taxes, and contingency.

The analysis considered replacing the I/O with low-density I/O (8 channels/card), high-density I/O (32 channels/card), and electronically marshalled I/O. The plant staff wanted to reuse as much of the existing cabinets as possible, and reuse some of the existing wire marshalling infrastructure. The plant had two rack rooms 300 feet apart. The cutover would occur during a plant turnaround so the analysis did not have to consider a hot cutover case.

Gordon enumerates some assumptions. Some of these included:

  • Cabinets have commonly used dimensions with a 19″ rail
  • Power and networking connections are included in the estimations
  • DeltaV controllers and I/O won’t be mounted in existing marshalling or field termination cabinets
  • Existing wiring does not have enough slack to reach DeltaV controller I/O locations
  • Electronically marshalled I/O can be oriented to accommodate existing wiring in the same cabinet
  • No new field wiring or instrumentation is included in the scope

For each case, the team performed a project task analysis. This analysis looked at the work associated with the new controllers and the associated wire marshalling. For the base case with low-density I/O, the work steps associated with the new controller included I/O lists & controller sizing, cabinet layout, power & grounding for controller and I/O cards, and I/O wiring schematics. The marshalling tasks included cabinet layout, terminations / interposing relay design, wiring schematics, and home run cables between the two rack rooms.

For the case with electronic marshalling, the steps eliminated for the new controllers were I/O card power and grounding, I/O wiring schematics, and home run cables. Steps were added to the marshalling tasks including the CHARM I/O card assembly, power and grounding for the individual CHARMs, and network layout.

Through this project task analysis, the electronic marshalling case estimated 63% lower installation costs, and 38% lower E&I design costs. The cost of the control system hardware was higher for the electronic marshalling case. Overall total installed and commissioned cost was 26% lower for the electronic marshalling case. With the high-density I/O case, the cost differential was reduced to 8%. Gordon notes the electronic marshalling case also provided single channel integrity, redundancy down to the individual I/O channel, design and installation flexibility, and the ability to bind each I/O channel to any controller up to 4 controllers per CHARM I/O card.

Gordon sums up his findings that the electronic marshalling approach reduces DCS cabinet design and complexity of the drawings, reduces wiring terminations and multi-core home run cables, reduces rack room footprint with the amount depending on whether the CHARMS are located in the rack room or out in the field junction boxes with a network connection back to the rack room.

If you’re among the ARC Advisory Group’s $53B club and at the Emerson Exchange, you may want to attend one of Gordon’s two workshops. His presentation is loaded with visual builds to better convey the alternatives in this analysis.

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