Servo Drive Upgrade for Wastewater Treatment

The existing servo system on the sludge press was based on a legacy Siemens 611U platform that had reached end of life. Spare parts were no longer available, and the client faced increasing risk of unplanned downtime on a machine critical to their wastewater treatment process.

Thomas Hadden took technical ownership of the upgrade from assessment through to commissioning. The first step was to extract and review the existing drive parameters and control behaviour, then specify suitable replacement servo motors and design a complete upgrade path to the Siemens S120 modular drive platform.

To reduce commissioning risk on what was a production-critical machine, Thomas recreated as much of the original control environment as possible within the electrical workshop, including PLC, HMI, and servo drives. This allowed functional testing and validation of control behaviour before anything was installed on the live machine.

As part of the upgrade, Thomas introduced an interim Siemens S7-1500 PLC to manage the servo axes using Siemens Technology Objects. This enabled more structured axis handling, including automatic axis alignment prior to movement and improved jog behaviour with variable speed based on operator input duration. These changes improved both operator usability and motion control precision.

The physical upgrade was carried out during a planned one-week maintenance window. Thomas led the electrical modifications and software integration, working closely with the site engineer and an external mechanical contractor. Following recommissioning, he led the fault-finding and optimisation phase to resolve integration issues and stabilise operation under production conditions.