A System-Level Functional Safety Architecture for Industrial High-Voltage DC Networks Beyond 800V

The increasing electrification of industrial production environments is accelerating the demand for scalable, efficient, and safety-oriented direct current power distribution systems. While industrial DC grids up to approximately 800 V have reached an initial level of technical maturity, higher-voltage DC architectures still lack a coherent and system-level functional safety framework. Existing research and industrial guidance predominantly address protection and safety at the level of individual converters, breakers, storage units, or local fault phenomena, whereas a holistic treatment of hazards, safety-related functions, interface responsibilities, and integrity requirements for interconnected industrial DC grids remains insufficiently developed. VDE SPEC 90037, published in November 2024 and derived from the DC-INDUSTRIE/DC-INDUSTRIE2 context, provides an important system description for industrial DC microgrids, but it does not yet constitute a complete functional safety architecture for higher-voltage interconnected DC networks. This paper addresses this gap by proposing a system-level functional safety architecture for industrial DC networks beyond 800 V based on the principles of IEC 61508. The scientific contribution of the paper does not lie in the development of a dedicated simulation methodology. Instead, it consists in the structured transfer of functional safety lifecycle logic, hazard and risk analysis, and Safety Integrity Level allocation to industrial DC infrastructures with decentralized infeeds, multiple fault-current contributions, and DC-specific fault dynamics. A structured hazard analysis is used to identify critical fault scenarios such as series arc faults, pole-to-ground faults, pole-to-pole short circuits, voltage imbalance in bipolar operation, battery-related faults, and communication loss between supervisory and local control. These hazards are systematically mapped to safety-related functions, safe states, and response patterns such as selective isolation, degraded operation, current-limiting coordination, and autonomous fallback behavior. In addition, selected formal relations are introduced to express system-level integrity allocation, electrical fault contribution limits, and DC-specific fault escalation mechanisms. The result is a first integrated, norm-based architectural framework for the functional safety design of industrial DC networks beyond the present maturity range of existing low-voltage factory DC concepts.

Keywords: Industrial DC Grids, High-Voltage DC Networks, Functional Safety Architecture, IEC 61508, SIL Allocation, Hazard and Risk Analysis, Arc Faults, Pole-to-Pole Short Circuits, Selective Isolation, Decentralized Power Systems.