Replacing an outdated control system with one utilising CC-Link has enabled the operator of a large overhead crane to benefit from energy savings, reduced maintenance and smoother crane movements.
CC-Link has played a vital role in the refurbishment of a large overhead crane at the EMZ foundry in Enakievo, Donetsk, in the Ukraine, improving productivity and making such significant energy savings that payback on the control system investment will be only months.
EMZ, one of the largest foundries in a region known for its heavy industry, runs a policy of constantly modernising and upgrading its capital plant. Much of the mechanical and electrical equipment, such as gearboxes and motors, are designed to run for decades with regular maintenance and overhauls. However, the electronics and control systems benefit from complete replacement in order to realise the benefits of newer technologies.
When it was time to rebuild one of the company's critical overhead cranes, specialist control systems engineers from Kiev-based CSC Automation were asked to review the existing installation. They advised that a complete strip out and replacement with a new state-of-the-art system would cost much the same as a piecemeal refurbishment. Significant performance benefits would be immediately apparent, energy savings would recoup much of the cost within a year, and the new system would provide a platform for future developments and enhancements.
CSC's engineers were keen to use an open communications architecture to reduce wiring and ensure that future work, such as replacing time-expired field devices, would be as simple as possible.
According to CLPA-Europe (the CC-Link Partner Association within Europe), CC-Link is the preferred open network in the Ukraine, as is the case throughout East and Central Europe. CSC is well acquainted with the technology, having designed and installed many CC-Link systems over the last five years, and EMZ thought it best to go with such a proven and established solution.
CC-Link is an open field device-level networking technology that provides high-speed, deterministic communications, linking a wide range of automation technologies over a single cable. It is suitable for machine, cell or process control in manufacturing and production industries, and is rugged and reliable for use in heavy industrial environments, such as foundries, steel plants and quarries.
Essentially, the EMZ project was a six-axis drive system and CSC identified Mitsubishi drives as having dedicated crane drive software and a considerable track record in similar applications. This led to the decision to fulfil all the processing requirements through a single Mitsubishi Q-series PLC, and to provide operator information through one main and two secondary HMIs (human-machine interfaces).
The final part of the system was a regenerative power converter. This enables the crane to recover electrical energy that would normally be part of the system losses. This reduces overall electrical consumption so much that the savings became a significant consideration when costing the project.
All these field devices are connected individually onto the CC-Link link network, with no need for complicated interfacing. Not only does this mean that system build time is significantly reduced, but the devices can be swapped out as necessary for maintenance, upgrade, replacement or repair.
The new control system has been in place and running for some months. CSC and EMZ have just completed a post-installation review and noted that the crane operators have adapted to the new regime and are reporting better operation with errors and accidents down by over 80 per cent; movements are smoother, reducing wear and tear of the mechanical components; and the regenerative energy savings have won plaudits from senior management.
Furthermore, the CC-Link network has performed faultlessly, with the speed of installation impressing so much that EMZ is likely to standardise on it for all future control engineering projects.