Financial benefits of retrofitting open fieldbus networks

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John Browett of the CC-Link Partner Association (CLPA) explains how upgrading automated manufacturing processes using open networks can provide major cost benefits, while also improving system performance.

Financial benefits of retrofitting open fieldbus networksIt is very easy for politicians to say: "Let us improve the productivity of our industrial base." But many European manufacturing companies already have their factories and plants working at above global average efficiencies. So what else can be done to increase output?

The first practical issue to address is finance. It is a rarity when there is more than enough money to go around. Usually there is fierce competition between every department in a company to secure investment funding; and when production wins, the funds have to be spent wisely.

So let us briefly look at the main cost elements of an automation project. The hardware is a major expense; and the skilled engineers that design the systems also command high rates. In addition, there is also the often- overlooked cost in cabling of the system. Cable itself is relatively inexpensive, but installing it is time-consuming. In many instances the upgrading or extending of an existing system can take more time than installing a new system from scratch.

Simple alternative

There is, however, an alternative to conventional wiring systems, and one that cuts costs substantially for both existing and new projects. This is to use a single ring or fieldbus communications topology, where field devices are 'daisy-chained', rather than being individually wired back to a controller.

In moderate to large plants, using this option results in notable savings in the amount of cable used. But, more importantly, the cabling operation is reduced in scale by orders of magnitude; and the cabling itself is so simplified that it is much easier to maintain and reconfigure – thereby reducing installed costs on an ongoing basis.

The facilitator to achieve these control system benefits is an open fieldbus, such as CC-Link. In essence, CC-Link sends the right signals to the right field devices, and does it in a time frame that matches the old dedicated wiring model. Another major advantage of CC-Link is that because it is open, users can even utilise equipment from different manufacturers in a single system. This might mean one company's inverter communicating with another company PLC, interfacing with a third company's HMI, along with sensors from multiple sources. In a new-build project this facility enables users to choose best-in-class equipment. More importantly, in projects such as a retrofits or upgrades, the problems of legacy equipment not being able to communicate are effectively overcome. Furthermore, in a maintenance situation, if the original supplier's inverter is not available, perhaps an alternative supplier's product can be substituted instead, providing a fast recovery from a breakdown.

The net effect of this benefit is that machinery is retrofitted rather than scrapped, resulting in greatly reduced project costs. In addition, disruption to production is reduced and commissioning becomes much quicker and easier.

Rates of adoption

It is significant that open networks have been around for 10 years or more, but their usage is not uniform across Europe. They have been the de facto choice in Germany for some time; most of industrialised Europe is following this lead, but lagging by between three and eight years.

Japan is probably on a level with or slightly ahead of Germany. Its neighbouring Asian economies, which have also become manufacturing powerhouses, are well advanced with installing open networks. The same is also true across North America.

CC-Link is finding a welcome home in Central and Eastern Europe and the old Soviet-bloc countries. These economies are rebuilding manufacturing facilities that were typically established in the 1950s. But they do not have to work through the technologies of the 1960s, 70s, 80s and 90s to catch up: they are thrusting straight into the best today has to offer and aiming to build world-class facilities.

Russian railways

An excellent example of this process in action is the Russian railways. The Russian Railways Corporation is one of the world's three biggest railway companies, transporting more than 1.3billion passengers and 1.3billion tons of freight every year. Its 85,500km network is the second-largest in the world, extending across eleven time zones from the Black Sea to the Pacific. Almost everything in Russia depends on the railways. Around 80 per cent of all goods and 40 per cent of all passengers are carried by rail. Huge distances and some of the most extreme environmental conditions in the world place a very heavy burden on the rolling stock, which includes around 20,000 locomotives, 25,000 passenger cars and 630,000 freight cars.

Added to the many operational problems faced by the Russian Railways Corporation in its everyday operations is the fact that its rolling stock is showing its age; modernisation is, therefore, an absolute necessity. Along with its other initiatives, the company is accelerating the use of modern manufacturing and automation to improve efficiency and productivity of the rolling stock maintenance facilities at Magnitogorsk in the Southern Urals.

All operations involved in the maintenance and refurbishment of bogie components have been automated. This involved development of a control system based upon the latest generation multi-processor programmable logic controllers (PLC) and motion controllers. The control system is integrated with other completely new equipment, and with machinery that had been in place for many years.

The resulting overall system incorporates machine tools, welding robots, conveyor and handling systems and an RFID (radio frequency identification) tag system for component tracking, providing a comprehensive system that includes a CC-Link fieldbus network and HMI control terminals. In addition to fast and secure communications, the new system also provides full transparency for all the plant and machinery. It was all installed with the minimum of downtime, is easy to operate and has already proved robust reliable and adaptable to change.

Any objective assessment would rate the new Magnitogorsk facility as world class - which is a complete turnaround compared to the old situation. A key element in the project was the replacement of the antiquated wiring with a CC-Link network, and exactly the same principles can be applied to smaller scale less extreme projects throughout Europe.

07 June 2011

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