Power, Utilities and Generation

Like the industry itself, our experience in this field is quite diverse. Downey Engineering staff are involved in the day-to-day support of systems across multiple sites in including dedicated backup generator control systems and the many support services control systems in place at coal-fired power stations.

Case Study

PLC5 to Contral Logix Migration


One of our clients is tackling head-on the problem of ageing legacy Control System Hardware. Many Control systems designed and built 20+ years ago were built extremely well with solid, reliable hardware. The problem remains though, as that hardware ages, faults will inevitably occur, replacement parts are more difficult and expensive to obtain and technical expertise on ageing systems harder to come by.

Through a well-planned feasibility and budgeting phase, this client made the decision to upgrade significant elements of their control system with a staged upgrade project.

The Challenge

To progressively upgrade four separate but interrelated control systems from Allen Bradley PLC5 Hardware to newer Rockwell Automation Control Logix Hardware. An absolute minimum of downtime was permitted for any changeover and a fast start-up expected with minimal complications.

· 4 Separate Systems each with redundant CPU’s

· A Total of 16 Racks of I/O > 4200 I/O points

· Multiple Ethernet Networks with VLAN configuration

· Four HMI Upgrades

The Solution

The old Remote I/O network structures were replaced with self-healing Fibre Optic Redundant Rings using Allen Bradley ETAP Modules and EN2TR Communications modules in the Remote I/O racks. The following was the typical process employed for all systems.

All I/O modules were replaced with new 1756 series Modules using the existing terminations along with the Rockwell I/O wiring conversion system. Careful selection ensured that the correct modules were used and no re-terminating of any of the existing input or output cards had to be performed.

Existing PLC 5 Code was converted using a number of different tools including the conversion tools supplied by Rockwell and our own custom methods, to ensure Tag names, comments and program structure was kept as close as possible to the existing PLC5 Code but also taking advantage of newer Control Logix tags and features. The Panelview HMI’s were also upgraded and converted and all direct references were modified to Tags.

The entire system was set up for Bench Acceptance Testing in our workshop. Simulation code was developed and employed to aid in the testing to minimise any site disruption for installation and commissioning. Every facet of the existing PLC5 code was tested on the Bench along with the converted Panelview configurations.

Prior to changeover, the new Fibre Optic Network was installed and pre-tested. For the first system changeover, the Physical installation of four remote I/O racks (approx. 620 I/O) and redundant processor racks was completed within a day. The Rockwell PLC5 to Control Logix conversion kits were used to absolutely minimise downtime and the chance for wiring error.

The Result

System hardware changed out in a single day. The new Control program was fully commissioned during actual production start-up and completed with no delay or disruption to production. A terrific team effort be all concerned meant an extremely satisfied client and a successful project delivered in Full and On Time.

Four of these systems have been changed over with similar results making this project one of our proudest achievements.





Related Services:

PLC Programming
SCADA and HMI Programming

Related Industries:

Power, Utilities and Generation


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