A quarry doesn’t fit in one room. Crushers, trunnions, conveyors and dust suppression pumps sit spread across the site, and every sensor needs a controller. When The Gerken Companies expanded its Custar limestone quarry in Northwest Ohio, the legacy control system couldn’t keep up.
The problem
The new, higher-capacity plant meant more crushers, more sensors and longer distances between equipment. Wiring it all back to one control room would have meant long, costly cable runs. The leading competitor’s proposal came in at double the investment Gerken had in mind.
The fix
Gerken turned to AMPS Industrial Controls, a UL508A panel builder and system integrator based in Holland, Ohio. AMPS built a distributed architecture around the Unitronics UniStream US15, a PLC + HMI with a 15.6″ touchscreen. Three modified shipping containers, MCC1, MCC2 and MCC3, were placed at strategic points on site. Each houses its own UniStream controller, motor starters and VFDs, so cabling stays short. A separate sub-location controls the high-dust suppression water pumps over Unitronics’ Ethernet-based I/O.
MCC3 is the hub. It manages the haul truck dump zone, the primary crusher and the surge pile, and the control tower sits there too. Using VNC, a single operator can view and control every networked PLC from one PC.
The three controllers share status continuously over Modbus TCP. The UniStreams also read Finder motor-protection devices over Modbus RTU, so amps, overloads and run verification show up in real time. AMPS built the logic in UniLogic with equipment protection in mind:
A heartbeat between PLCs triggers a controlled shutdown if communication drops. If a conveyor at MCC2 faults, dependent upstream conveyors at MCC3 stop automatically, so material doesn’t pile up. A staggered start sequence brings conveyors and crushers online one by one to limit inrush current. The HMI lets operators switch between a view of one MCC and a process view showing only the conveyors needed for a given stone grade.
The result
AMPS delivered the system at roughly half the cost of the competing bid. Automatic upstream shutdown has virtually eliminated the downtime and labour of manual cleanouts. SMS notifications and alarm alerts keep operators informed, and the modular UniStream platform can grow with the quarry.
AMPS lead engineer Alex Foulke puts it this way: “UniLogic lets you build a consistent alarm structure across multiple PLCs.” Every fault is time-stamped and tied to the process state. “So when something trips, the operator sees the root cause, not just the symptom.”
Running crushers and conveyors across a spread-out site? Talk to Vision Automation about a UniStream-based control system for your plant.
This is a partner success story, originally published by Unitronics. Vision Automation is the authorised Unitronics distributor for Southern Africa. Read the original case study on the Unitronics website: https://www.unitronicsplc.com/testemonials-category-carrousel/?category=material+Processing&tid=23829
Sources: Unitronics success story
