Traditional marshalling aims to provide reliable interconnections between field instruments and a central control system. It may include provision for intrinsic safety, signal conditioning, relay interfaces, surge protection and loop disconnect.
While the task seems simple in principle, in reality it is complicated and time-consuming. A typical cabinet will have 20 different marshalling components and may require up to eight interconnections on each loop. That means eight opportunities for a wiring error. A single change will affect design drawings, the Bill of Materials (BOM) and cabinet layout.
Once a system is live, marshalling changes become even more complicated. Failure in a wiring connection has the potential to cause immediate and severe incidents, potentially triggering a plant shutdown costing millions of dollars. Smart Universal Marshalling (SUM) systems – such as Eaton’s MTL SUM5 – offer both practical and financial benefits over traditional marshalling while reducing risks – all of which contributes to an improved Total Cost of Ownership (TCO).
SUM Approach
1. Standardisation
Smart universal marshalling solves the problem of complexity by reducing the number of components. Traditional marshalling considers each function as a separate entity, whereas SUM allows for the integration of these functions. For example, one MTL SUM5 universal ADIO isolator module can replace 20 different MTL4500 single-channel modules. Standardised modules reduce the number of items on a BOM, so ordering parts and keeping track of design changes becomes easier for purchasing teams. Standardisation comes into its own when design changes occur during detailed engineering. Replacing modules or adding functionality after the conceptual phase adds uncertainty to a project. This can result in overruns and loss of credibility. Using standardised modules allows engineers to make design changes without changing module specifications.
2. Simplicity and compactness
SUM eliminates the need for separate cabinets for each function. A single cabinet design caters for them all. It also eliminates the need for a separate loop disconnect terminal. Each terminal base includes this functionality.
Standardised and modular structures make design changes much easier to handle: for example, swapping an ADIO isolator for a temperature isolator without any other changes to the loop. Configuration changes can be done at the cabinet via a push-button or a PC. Surge protection modules can also be moved to a different channel or added once surge studies are completed, which often happens later in the design phases. These features greatly reduce installation and configuration time.
SUM solutions are compact and cater for maximum packing density. Two or three columns fit into each side of an 800 mm wide double-sided cabinet providing all marshalling functionality for 512 or 768 channels. More modules per cabinet mean fewer cabinets in total. Eaton calculates that a reduction of 30% to 50% is possible using smart universal marshalling.
3. Flexibility
Modern production facilities must be able to respond quickly to changes in market demand or supply chain disturbances. Flexibility is crucial for sustained business success. Marshalling systems must, therefore, allow changes to configuration without extensive rewiring and delays. An ideal marshalling solution would have connectivity to 5G and Artificial Intelligence (AI) technology and integrates seamlessly with automation systems. Traditional marshalling solutions cannot meet these requirements, but smart marshalling solutions can.
The MTL SUM5 allows for changes to module configuration in the cabinet. There are fewer hardware changes required when new designs or operational changes are needed. The modular infrastructure also makes it easy to add to the system without rewiring. Another way SUM adds value is in the usability of spare capacity. Most marshalling solutions are designed with 20% extra capacity, but industrial plants seldom use the spare capacity loops because of the risks of moving wiring from a ground terminal to a Field Termination Assembly. With SUM, the grounding is accomplished via a plugin module rather than hard wiring. As a result, removing the ground module and inserting an isolator module makes the extra capacity available without the risk.
Reducing CAPEX and OPEX
Eaton has worked with partners to quantify savings in initial costs for SUM, particularly in relation to the reduced cabinet count. An 82% reduction compared to traditional marshalling solutions is possible.
SUM makes a substantial contribution to lowering ongoing operational costs, too. A 65% reduction in spare component types means a lower stock holding and more efficient procurement process. Maintenance technicians benefit from reduced complexity of standardised cabinet designs, which lowers the risk of human error. Troubleshooting is also simpler. The MTL SUM5 has LEDs to indicate power, function and status so maintenance technicians save time by having the right information available for diagnosing problems. The terminal holds its own configuration information making it easy to swap out modules seamlessly.
Comparisons of operational costs using smart marshalling versus traditional methods indicate a 65% saving is possible.
Space savings
Space is at a premium in centralised control rooms, which are generally built to exceptionally high blast-proof specifications – making them an expensive investment. Reducing the number and size of marshalling cabinets reduces the requirement for space and, therefore, the cost of the building. It also reduces the amount of cabling and air-conditioning required. Even when marshalling cabinets are eliminated by remotely mounting I/O in field enclosures the MTL SUM5 compact standard footprint reduces the size and cost of the enclosure required.
Eaton calculations show a saving of 69% in terms of end-user costs for a smart marshalling project versus the traditional approach. Most of these derive from the reduction in cabinet space.
Lowering risk
Connection failures and human error are the most common cause of incident for traditional marshalling solutions. SUM lowers the risk of an incident by simplifying the system. All marshalling functions reside in a standard cabinet design, and the quantity and complexity of hard wiring are greatly reduced. These factors reduce the risk of human error, which could result in a major plant incident.
MTL SUM5 meets ATEX, IECEx and North American certification requirements, making it suitable for international use. It is designed for location in Zone 2 hazardous areas and has a wide ambient temperature operating range. SUM is, therefore, a viable solution for even the harshest operating conditions.
Conclusion
Smart universal marshalling offers substantial benefits over traditional marshalling. It simplifies the design process as well as system installation and lowers operational and maintenance costs. Eaton’s MTL SUM5 offers TCO benefits while enabling the kind of flexibility and connectivity industrial plants need.
