ISO 5474-3:2024

Overview

ISO 5474-3:2024 - Electrically propelled road vehicles - Part 3: DC power transfer - defines functional and safety requirements for conductive DC power transfer between electrically propelled road vehicles and external electric circuits. Used together with ISO 5474-1, this standard covers conductive charging in mode 4 (per IEC 61851-1) for isolated DC EV supply equipment and applies to vehicle power supply circuits for voltages up to 1 500 V d.c.. Annex B gives an outlook on megawatt charging. The document focuses on power transfer and safety; it does not cover simultaneous multiple interfaces, power transfer while driving (electric road systems), mopeds/motorcycles (ISO 18246), or comprehensive manufacturing/repair safety guidance.

Key Topics

The standard addresses technical and safety aspects relevant to DC EV charging, including:

• System architecture and environmental/operational conditions for vehicle inlets and couplers.
• Protection against electric shock: insulation resistance, touch current, insulation coordination, compatibility with external safety devices, and requirements for unmated vehicle contacts.
• Insulation resistance monitoring (IMD/IM system) and compatibility with external insulation monitoring.
• Thermal protection and overcurrent: thermal sensing, thermal cut-outs, overcurrent protection, residual energy after disconnection, and arc protection.
• Protective conductor requirements and continuity monitoring.
• Electromagnetic compatibility (EMC) requirements to limit interference during DC power transfer.
• Protection against unintended power transfer and functional requirements like disconnection devices, control pilot functions, and latching device control for vehicle couplers.
• Reverse power transfer (additional requirements where applicable).
• Marking, owner’s manual requirements and comprehensive test procedures (protective conductor resistance, insulation resistance, withstand voltage tests, touch current, temperature tests).
• Informative annexes covering Y capacitance measurement and a forward look at megawatt charging applications.

Applications and Users

ISO 5474-3:2024 is intended for:

• EV manufacturers defining vehicle power supply circuit requirements.
• EVSE designers and charging station manufacturers implementing isolated DC charging systems (IEC 61851-23).
• Component suppliers (vehicle inlets, couplers, sensors, protective devices).
• Test laboratories and conformity assessors performing insulation, touch-current and withstand tests.
• Safety engineers, regulators and infrastructure operators assessing risk and ensuring compatibility between vehicle and external circuits.

Practical benefits include safer high-voltage DC charging, standardized interfaces for mode 4 conductive charging, and guidance for next‑generation high‑power (megawatt) charging systems.

Related Standards

• ISO 5474-1:2024 (General requirements for conductive power transfer)
• IEC 61851-1 (EV conductive charging - general)
• IEC 61851-23:2023 (DC EV charging stations)
• IEC 62196-3 (DC vehicle couplers)
• ISO 6469-3:2021 (Electrical safety of EVs)
• ISO 26262 (Functional safety for road vehicles)