Electrolyser Process Control & Protection System


Servelec Controls was contracted by a large manufacturer of hydrogen energy systems to supply a turnkey, safety rated control system for a water electrolysis plant, all within an ATEX environment.

Designed for use by a large utilities company in Germany, the plant produces hydrogen gas from water and mixes this with natural gas. This mixture is injected into the German gas grid for use by consumers.

Servelec Controls’ knowledge was utilised to produce a control and protection system that can be run autonomously while also monitoring safety critical data. The supervisory system provides a visualisation of the plant and key processes and alerts the user to any system anomalies.

Adhering to the clients’ functional safety and hazardous area needs, the solution employed Siemens fail-safe S7-300 F-rated controllers with suitable ATEX protection employed within the hardware design. A Siemens WinCC SCADA solution provides local control and remote access to the plant.

Scope of Work

Servelec Controls scope of supply included the following:

  • Hardware and software platforms design and build
  • Network communication
  • Equipment control
  • Automated process area sequencing
  • Human Machine Interface (HMI)
  • Electronic data and record storage
  • Protection System to BS EN IEC61511/61508
  • Compliance with Ex/ATEX requirements


The solution deployed to meet the functional safety and ATEX requirements included a Siemens S7-300F PLC which utilised both safety and standard I/O modules to provide safe control and monitoring of the process. A number of Safety Instrumented Functions (SIFs) were implemented to a Safety Integrity Level (SIL) 1.

Siemens GSM and GPRS modules provide access for remote monitoring of the process from the site in Germany. A Siemens TP1500 15” Touchscreen running WinCC provides the operator visualisation of the complete process. 

Pepprl and Fuchs intrinsically safe barriers were used to provide a safe interface from the hazardous area
signals which originated in Zone IIC T4.

All the equipment was housed within a custom cubicle which was designed, built and tested in-house by Servelec Controls in our dedicated workshop.

Electrolyser Process Control & Protection System