Retrofit drives future efficiencies

Cummins Ltd, based in County Durham, is a diesel engine manufacturer supplying the automotive, construction, material handling, marine, military and power generation industries. A vital element of the manufacturing process is the testing undertaken for each engine on three bespoke test cells. Any problems with this part of the manufacturing process can have serious repercussions as far as overall operational efficiency is concerned.

Facing performance issues around an obsolete DC drive and difficulties sourcing spare parts, Cummins Ltd wanted to ensure the test cells would provide high availability well into the future. After discussions with Siemens and Cleveland Systems, it was agreed that this would require the design, installation and commissioning of a new and integrated drive and automation control system. The answer lay with a Siemens Sinamics DC master drive and S7-300 PLC linked over a Profibus interface to provide the reliability and increased flexibility Cummins was seeking. Importantly, the Sinamics drive had to also control the existing 37kW DC motor, which would remain in situ through the retrofit project.

Tam Ashcroft, director at Cleveland Systems, says: "Cummins needed certainty that its new drive and control system would provide the high levels of plant availability required. The innovative solution we have delivered is based on the Sinamics platform which has given the front end of the system a new, modern look and better tools for important diagnostic tasks, while at the same time blending with the familiar and traditional system architecture."

The Siemens Sinamic DCM Drive was selected to control the existing 37kW DC motor. In addition, the S7-300 PLC was expanded to receive analogue signals from the test control PC connected to the drive via Profibus to allow full PLC control of the set points and commands. The devices were programmed to give variable cranking speeds for specified engine types and to aid the test cell operators, all parameters and faults are displayed on dedicated HMI machines.

A critical element of the project was the ability to avoid interruption to ongoing production, and the project team had to ensure the new system could be installed without affecting day-to-day operations. To this end, the project implementation was staggered to work around this important requirement.

Fully supportable system

John Inskip for Siemens Industry is clear about the benefits this modernising retrofit project has delivered for Cummins Ltd. He says: "The operational efficiency of the test cells has been markedly improved. The company now has a fully supportable system based on Siemens Totally Integrated Automation (TIA) approach, and a modern drives system with full documentation, configuration and diagnostic software. For ease of use, all parameters, reference values and faults are clearly displayed, along with help texts on dedicated HMIs at each drive panel. Drive commands and set points sent from the PLC can now be easily adjusted by Cummins engineers to provide increased production flexibility."

By implementing the Sinamics DCM drive system, a traditionally based drive technology has been modernised through up-to-date architecture and control philosophy. Data acquisition from higher-level controllers is now far easier to obtain, and is helping to underpin the overall operational efficiency improvements of the test cells as management can use it to inform important decision-making.

Desmond McMenamin, Plant Manager from Cummins Ltd comments: "To ensure we could continue to meet customer quality and delivery requirements, we wanted to improve our engine test facility. As such, the combination of a supportable, reliable and intelligent automated drive and control system with its associated operational benefits is helping us to drive our manufacturing operations forward."

To learn more about integrated drive and automation control systems, please go to www.siemens.co.uk.