Keeping the Line Rolling: Drive System Retrofit for a Steel Coating Operation
How CSI replaced 18 obsolete drives on a roll forming line with a modern Sinamics S120 system — upgrading the electrical backbone of the machine while preserving the existing mechanical infrastructure, field devices, and panel hardware.
Industry
Metals
Service
Migrations & Retrofits
Platform
Siemens Sinamics S120
Scope
Coating line drive system
A steel coating facility in the Hamilton area was running a coating line powered by 18 Siemens Masterdrive units and 2 line modules on a shared DC bus. The Masterdrives had reached end of life — spare parts were increasingly difficult to source, and any drive failure risked taking the entire line down. The mechanical side of the machine was in good working condition, so the customer needed a controls retrofit that replaced the obsolete drive technology without requiring changes to motors, cabling, field devices, or the existing operator interfaces.
CSI engineered a one-for-one drive replacement, swapping all 18 Masterdrive motor modules and 2 line modules for a modern Sinamics S120 system with 18 S120 motor modules and 2 Smart Line Modules. The retrofit was designed to fit within the existing cabinet footprint and reuse all existing motors, encoders, cables, junction boxes, limit switches, cam switches, proximity sensors, and solenoid valves.
The engineering process started with a site visit to document the existing control architecture, back up all drive parameters, and capture the PLC program. CSI then created uploads from every Masterdrive, analyzed the parameter sets and Profibus telegram structures, and used that as the basis for conversion to the new S120/CU320 platform. New Profibus telegrams were implemented in the PLC hardware configuration, and the PLC logic was adapted to reflect the new drive architecture — maintaining the same machine functionality the operators were accustomed to.
CSI produced a new electrical drawing set in their automated EPLAN package, covering all changes required for the Sinamics system. All Siemens hardware components were specified by Siemens and purchased directly through them.
Commissioning took place over the 2022 winter shutdown — 10 days to complete demolition of the old drives, installation of the new Sinamics system, power-on, testing, and full commissioning. CSI’s emphasis throughout was a seamless transition for operations: no operator interfaces were modified, so operators were able to resume production immediately following commissioning without retraining or adjustment.
During the engineering phase, CSI also identified that the existing system was using incorrect fusing for branch protection on the 900V DC bus. CSI designed and supplied suitably sized branch protection, improving the electrical safety of the line as part of the retrofit scope.
The retrofit eliminated the obsolescence risk on all 18 drive positions and delivered immediate operational improvements. Line downtime has been reduced significantly, while serviceability and troubleshooting capabilities have been modernized through the Sinamics platform’s built-in diagnostics. The seamless commissioning approach meant zero disruption to operator workflows — production resumed immediately after the 10-day changeover.
Demolition to production
Drives replaced
Operator retraining required
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