CERN SCADA Systems 2020 Large Upgrade Campaign Retrospective

In this paper we report the experience from a large-scale upgrade campaign of SCADA control systems performed during the second LHC Long Shutdown at CERN. Such periodical upgrades are dictated by the ever evolving SCADA WinCC OA system and the CERN frameworks evolution used in those control systems. These upgrades concern: accelerator control systems, e.g. quench protection system, powering interlocks, magnet alignment; control systems devoted to accelerator facilities such as cryogenics, vacuum, gas… and other global technical infrastructure systems as well as the CERN electrical distribution system. Since there are more than 200 SCADA projects covering the CERN accelerator complex and technical infrastructure, any disruption requires careful coordination, planning and execution with process owners. Having gained experience from previous campaigns and reaching a new level of automation we were able to make visible improvements by shortening the required time and reducing the personnel required. Activities, lessons learned and further improvements are presented as well as a comprehensive statistical insight of the whole campaign.