Applying DeviceNet in motor control centers at a cement plant

The Lafarge Cement Plant in Alpena, MI produces 2.5 million tons of cement per year from 5 kilns which each yield around 1250 tons per day. Plant control is distributed over forty PLC5s with over eighteen thousand I/O points, which have been installed over ten years. The kilns were the last major pieces of equipment yet to be tied into the PLC based supervisory system. PLC5s were chosen for the kiln automation based on this installed base and on the ease of expanding the existing supervisory system network to accommodate the kiln control. The plant architecture uses three layers of communication: first, remote I/O to communicate to the I/O subsystem from the PLC Processor; and secondly, a Data Highway Plus to communicate between processors and to the Ethernet gateway/data server. This gateway provides process data to the third layer, the process supervisory network. The process supervisory network consists of supervisory workstations running Intellution DMACs and the expert system LUCIE which is Lafarge's own application running on Gensym G2. This paper discusses the design and installation of a DeviceNet communication network to smart motor control centers (MCCs) on the three kilns at the Alpena plant. The DeviceNet link, which provides direct digital control and monitoring of motors, is linked to the supervisory system via the remote I/O link.