A new insulation monitoring device enhances safety in high-voltage DC fast chargers by simplifying system design, enabling early detection of insulation faults, and supporting multiple charging standards for reliable EV infrastructure.
As EV charging infrastructure moves towards higher power levels, ensuring electrical safety in high-voltage DC systems has become increasingly important. To address this need, Carlo Gavazzi has introduced the DRC61 insulation monitoring device, designed specifically for unearthed (IT) DC systems used in Mode 4 DC fast-charging stations. The device continuously monitors insulation resistance between the DC lines and protective earth, enabling early detection of insulation degradation before it develops into hazardous faults.
Unlike conventional insulation monitoring systems that require external voltage adapters for high-voltage operation, the DRC61 operates directly on systems up to 1000V DC, with a permanently admissible voltage of 1100V DC. This single-module architecture reduces component count, simplifies charger integration, and helps OEMs optimise space within fast-charging equipment while lowering overall system complexity.
The key features are:
- Supports system leakage capacitance up to 25 µF
- CHAdeMO mode supports 1.6 µF per conductor
- Factory default relay thresholds of 500 kΩ and 100 kΩ
- DIN-rail compatible compact industrial design
- Continuous positive and negative DC line insulation supervision
The device injects a measuring signal between the DC conductors and ground to continuously evaluate insulation resistance. When the measured resistance falls below configurable thresholds, it activates configurable pre-alarm and alarm outputs, allowing maintenance teams to identify deteriorating insulation before a critical failure occurs. This predictive approach improves charger availability while enhancing user safety.
For integration into modern charging platforms, the DRC61 includes an RS485 interface with Modbus RTU communication, enabling remote monitoring and configuration through charger control systems. Two configurable SPST relay outputs provide independent warning and alarm notifications, allowing operators to implement preventive maintenance strategies instead of responding only after faults occur.
The insulation monitor is compatible with both CCS and CHAdeMO charging architectures, making it suitable for globally deployed fast-charging stations. It also incorporates local and remote test and reset functions, LED status indicators, and continuous monitoring of system voltage to detect undervoltage and overvoltage conditions alongside insulation faults. The device follows a fail-safe operating philosophy by de-energising outputs during critical failures or auxiliary power loss and is UL 2231-1 and UL 2231-2 listed, supporting compliance with EV charging safety requirements. Beyond fast chargers, the DRC61 can also be deployed in battery energy storage systems, DC microgrids, and other high-voltage DC installations where continuous insulation monitoring is essential for reliable operation.
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