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StoneCo of Michigan selected Etheridge Automation
to implement automation for their Newport, MI quarry. StoneCo had a 10+ year
old PLC based automation system that had become increasingly maintenance intensive
and difficult to obtain replacement parts. The legacy system still required the operator
to control the plant feed and make major decisions on plant operations. StoneCo was
looking to improve the plant performance with the new automation system by incorporating
feed controls and limiting operator dependence. Etheridge Automation has been
automating rock quarries exclusively since the early 1980's. Stoneco liked their
control system's flexible interlocking features, feeder controls and their
aggregate industry experience.
Etheridge Automation has developed an aggregate processing automation system that
is modular in nature and can be scaled for the various sizes and configurations of
aggregate plants. At the core of the Etheridge Quarry Information Management System™
is a SoftPLC programmable controller that communicates over Ethernet to the control room
PC. Wonderware Intouch 10.0 is used for the HMI. Etheridge uses SoftPLC because of its
reliability, ease of use, processing power and flexibility.
Process Control
At the StoneCo Newport Facility, Etheridge Automation installed controls for
the Primary and Secondary crushing plants to control all operating equipment and
the plant feed. In the Primary plant, the SoftPLC control system increased the
production capacity by 20%, allowing the plant to cut the operating time from 10
hours per day to 8 hours. Additionally, major downtime events were greatly reduced,
increasing the plant availability.
In the Secondary system, the plant capacity was limited by the performance of the
screens, therefore increased tonnage throughput was difficult to achieve. The
improvements in the Secondary plant were realized in the increased uptime and
more consistent product quality. The automated feed controls anticipated and
reacted to changing operating conditions and prevented major downtime events, thus
improving plant availability.
Another major benefit was the flexible nature of the Etheridge equipment interlocking
features. The plant makes significant changes to the equipment layout every few days
to accommodate the different blend of products being produced. With the legacy PLC,
the interlocking of the equipment could not adjust to the new arrangements so the
equipment was left un-interlocked and the operator had to detect and respond to any problems.
With the Etheridge system, the equipment interlocks could be changed quickly with
the click of the mouse in the HMI. This flexibility allowed protection for the product
conveyors that had not previously been available. Having this interlocking in place,
along with Software Speed Switches™ on the product conveyors prevented hours of downtime
that would result from belt slippage and motor failures. Previously, when these belts
would fail they would have to be shoveled off by plant employees. By preventing these
failures, not only was downtime reduced, but employee safety was improved.
The PLC control system incorporated a SoftPLC CPU in the Secondary plant with a remote
rack in the Primary plant. The communications between the racks was accomplished with
SoftPIPE, which is a very reliable 5MB remote I/O network built into the SoftPLC CPU.
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