English 
East Japan Railway Company (JR East) and Hitachi have constructed the world’s first fully digital substation system for an operating railway line at the Koiwa AC Substation in Japan. They commercialized the system partially on November 13, 2026, and it became the first time for a domestic railway operator to deploy a railway substation based on the international IEC 61850 standard.
The revised system aims to ensure a steady power supply for railway operations, while optimizing substation installations. Digital information is transmitted via the optical fibre communication link connecting field equipment to the protection and control unit, which used to be held in several different pieces of equipment. These protections and controls are now integrated into Hitachi’s CPC Centralized Protection and Control.
The equipment is also reliable. The installation has backup communication paths and protection and control functions, so it can keep functioning even if one unit of equipment or one communication path fails.
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Construction demands too have been lowered by the transition to digital infrastructure. There has been an 80% reduction in the control cabling and a 60% reduction in space through the adoption of a common control panel. The delivery and installation of equipment is 50% faster and less material is used.
The system is being installed in the substation’s 22,000-volt gear. The rest of the 66,000-volt gear will go live in fiscal 2028.
JR East intends to include more deployments in its next-generation power supply control and protection system. Hitachi is also working on a similar fully digital system for the DC-electrified sections of railway, working towards a safer and more sustainable rail system.
日本語