Feature Wiring The lean approach to wiring


Traditional hard wiring is still the norm inside most control panels, however the introduction of new technologies mean there is now no longer a reason to ignore the benefits of bus-based panel wiring. Stuart Greenwood of Eaton’s Electrical sector, discusses the issue


DCS’s was underway. It is therefore hard to see this convergence as a new trend, as it’s been with us for at least a couple of decades. Convergence, however, continues to spread, and most modern automation systems now incorporate intelligent devices in the field – such as variable- speed drives with built-in intelligence, and electronic operator interface panels. With all of these devices linked to the central controller via net- work or fieldbus connections, it becomes difficult, or even perhaps almost meaningless, to distinguish between the PLC and the remainder of the automation system.


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Except, that is, within the control panel itself. Although conventional hard wiring of field devices has virtu- ally disappeared in all but the smallest of installations, traditional hard wiring is still the norm inside most control panels.


While the wiring runs are much


shorter inside the panel than outside, that’s no longer a valid reason to ignore the benefits that bus-based panel wiring – or ‘lean panel wiring’ – can provide. However, this omis- sion in automation technologies has now been addressed, and at least one bus-based lean panel wiring system – SmartWire-DT from Eaton’s Electrical Sector – is now available.


Making the connection SmartWire-DT allows all the devices


nce remote I/O modules became available, it could be said that the process of con- vergence between PLC’s and


within a control panel – motor starters, HMI panels, conventional pushbuttons and indicator lights, etc. – to be con- nected to the central controller, whether it’s a PLC or a smart relay, via a daisy-chain connection. Conventional control wiring is eliminated. With the best lean panel wiring systems, special components are not needed – inexpensive interface units are added to standard components in the same way that an auxiliary contact block is added to a contactor. This technology therefore cuts panel wiring time and, as it virtually elimi- nates the possibility of wiring errors, the time needed to test panels is reduced, as is the risk of problems during commissioning. Panel modifica- tions are also easier as instead of having to carry out extensive wiring changes for even the simplest modification, all that’s needed is to daisy-chain the new components to those already there. Possibly the biggest benefit, however, is that the use of lean panel wiring facil- itates the flow of information between components mounted in the panel. A suitably equipped motor starter could, for example, report the running current of the motor and the status of the protection device to the central con- troller, where this information could be processed and used to initiate further actions, such as sending a message to the HMI panel alerting the operator to an impending overload condition before a trip actually occurs.


Lean wiring


Lean panel wiring improves the transparency of the automation


Enclosure & Panel Building Solutions WINTER/SPRING 2013


SmartWire-DT allows all the devices within a control panel to be connected to the central controller via a daisy-chain connection


system. Since fieldbus- and network- based field wiring already supports information exchange, the addition of lean panel wiring means that any information about any aspect of the automation system’s operation and status can be made available, wher- ever it is needed.


This transparency is one of the key elements needed for lean automation, which is one of the reasons that the description ‘lean panel wiring’ for the new bus-based panel wiring sys- tems is preferred. The growing uptake of lean automation is arguably a much more significant trend than PLC/DCS convergence.


Lean manufacturing is a well-known concept that is based on identifying all sources of waste and inefficiency in a process and eliminating them. Lean automation extends this concept to automation systems, slimming down control panels, simplifying wiring, increasing data transparency and enhancing performance while reducing overall costs. With lean panel wiring, lean automation can now cover every facet of manufacturing processes, from the ERP system to an emergency stop button, and from the SAP package down to individual sensors.


Lean control panel wiring systems mark the final stage in the transition from traditional control system technologies to modern network- and bus-based tech- nologies, facilitating the implementation of transparent automation.


Eaton Electric T: 0161 655 8900 www.eaton.eu


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