When The Gerken Companies set out to expand their Custar limestone quarry, the equipment list was the easy part. More crushers, more conveyors, more sensors, spread across a footprint the site had never operated at before. The harder question was whether the existing control system could keep up with any of it.
It could not. And the reason had nothing to do with the rock.
Expanding a quarry means expanding distance. Every new crusher and conveyor sits farther from the control panel than the last one, and each still needs power, signal, and a way to tell the operator what it is doing. Route all of that through a single central controller and the costs show up in places nobody budgeted for: cable runs measured in hundreds of feet, conduit and trenching that climb faster than the equipment itself, and one panel carrying the risk for the entire operation.
Gerken did not need a bigger panel. They needed a different architecture.
Putting control where the equipment is
The system AMPS designed is built around three modified shipping containers placed strategically across the site. Each functions as a self-contained MCC location with its own Unitronics UniStream PLC, motor starters, and VFDs.
This is the core principle of a distributed control system. Rather than pulling every signal back to a single central point, a controller sits next to the equipment it operates, and the controllers communicate with each other across the network. Long cable runs largely disappear. So does the single point of failure. If one container has an issue, the rest of the site continues to run.
The containers were a practical choice as much as a technical one. They arrive weather-rated, they can be set on a pad without constructing a building, and if the quarry layout shifts in a few years, they can be relocated. Not every installation justifies a permanent electrical room.
All three PLCs report into one tower PC, where the operator monitors crushers, conveyors, and dust suppression from a single screen.
Logic that catches problems before an operator does
In quarry operations, the expensive part of a conveyor fault is rarely the fault itself. It is the twenty minutes before anyone notices, and the manual cleanout that follows once material has piled up on a stopped belt.
The Gerken system is programmed to prevent that sequence from starting:
Heartbeat monitoring between PLCs. The controllers check in with one another continuously. If one stops responding, the system recognizes the loss within seconds and triggers a controlled shutdown rather than allowing equipment to run blind.
Cascade interlock logic. When a downstream fault is detected, upstream conveyors halt immediately. Material stops feeding onto a belt that is no longer moving.
Alarms tied to process state. Every alarm is time-stamped, categorized, and linked to what the system was doing when it fired, so the operator sees the root cause rather than a screen full of symptoms.
As Alex Foulke, lead controls engineer at AMPS, describes it:
“Because the UniStreams are exchanging data continuously over Modbus TCP, we can diagnose interlocks and upstream and downstream dependencies from a single screen.”
That capability carries more weight than it might appear to. Most troubleshooting time in a distributed system is spent determining which piece of equipment actually initiated the problem. When the controllers already share state with one another, that answer is waiting on the screen.
With SMS notifications and remote access layered on top, the operator does not need to be in the tower to know something has gone wrong.
The number that moved the project forward
The competing bid came in at double the price.
AMPS delivered the same functionality, with stronger diagnostics, at half the cost.
On a project of this scale, that difference is not a line item. It determines whether an expansion moves ahead on schedule or waits another year. Gerken got a scalable, distributed limestone production environment and retained enough budget to complete the rest of the expansion.
Two things account for that gap. The first is component selection. AMPS is one of the largest Unitronics distributors in the United States, and the UniStream platform delivers what a comparably specified controller from a larger brand delivers, at a materially lower cost per point. The second is structure. Most projects involve a distributor, a panel shop, and an integrator, which means three markups and three handoffs where details get lost. At AMPS, all three happen in one building. The person who quotes the controller is the person who programs it.
Recognizing the same problem in your own operation
Most facilities do not outgrow their equipment. They outgrow their controls.
The warning signs tend to be consistent. Cable runs that keep getting longer with every addition. Faults discovered by walking the site rather than reading a screen. An operator who can tell something is wrong but not which piece of equipment caused it. A single panel that everyone treats carefully because the entire operation depends on it.
None of this necessarily calls for a full rebuild. What it calls for is an architecture sized to the operation as it exists now, and a controller platform priced so that scaling up later does not mean starting over.
AMPS has been building these systems out of Holland, Ohio since 1992, combining component distribution, UL508A panel fabrication, and in-house PLC and HMI programming under one roof.
If your controls are beginning to limit what your operation can do, get in touch. These conversations go better before the busy season than during it.
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