DC meters for High-power and Megawatt Charging

When providing charging infrastructure, accurate recording of the amount of energy is necessary and essential for billing in accordance with calibration regulations. Measurement specialist Isabellenhütte presents the IEM-DCR, the second generation of DC meters that meet these requirements. With certification complete, the meters are now available on the market.

Isabellenhütte currently offers various versions of the DC meter. The IEM-DCR-125, with a current measurement range of 125 A and voltage of 1,000 V, is suitable for DC wall boxes. The IEM-DCR-1000, with up to 1,000 A and an extended voltage range of 1,500 V, is designed for high-power charging up to 1.5 MW. It is the first meter on the market to cover the 1,500 V voltage class. The IEM-DCR-1500, with 1,500 A and also a voltage range up to 1,500 V, is ideal for megawatt charging applications and is currently undergoing certification.

Modular System with CAN Interface for Easy Integration

The IEM-DCR meters consist of separate display and sensor units, simplifying integration into charging stations. While the display must be externally visible to the end user, the current sensor can be installed anywhere inside the charging station. The two modules are connected and can be placed up to 15 meters apart. Alternatively, manufacturers can use the sensor unit as a stand-alone device (DCS) or as the basis for their own metering system.

A further development compared to the first generation of meters is a CAN interface for the transmission of real-time measurement data (current, voltage, temperature and power). This allows charging station operators to monitor their systems internally with high reliability. n addition, the new generation allows bi-directional measurements and the creation of charging transactions in OCMF format.

The energy meters also offer two options for compensating for cable losses. With customer-specific parameterization, the cable resistance is programmed into the meters in advance during production. Alternatively, dynamic four-wire measurement is possible. The IEM-DCR-125 offers two voltage channels, while the two large meter variants IEM-DCR-1000 and IEM-DCR-1500 offer four voltage channels. In future, parameters can also be adjusted in the field to offer greater flexibility.

IEM-DCS: Stand-Alone Version Without Display

Three additional meter variants—IEM-DCS-125, IEM-DCS-1000, and IEM-DCS-1500—consist only of the sensor unit. These are intended for markets where legally compliant energy reading is not required. They are also suitable for customers developing their own display solutions or needing a precise current/voltage sensor with signed values. These models share the same performance specifications as the IEM-DCR-125, IEM-DCR-1000, and IEM-DCR-1500.

Certification According to German Calibration Law and MID Completed

The IEM-DCR-125 and IEM-DCR-1000 have been certified and meet Accuracy Class B (EN 50470) and Class 1 (IEC 62053-41). In addition to the certification under German calibration law, the meters are also certified under the EU Measuring Instruments Directive (MID).

Application Examples

IEM-DCR meters from Isabellenhütte are already being used in early development phases by various charging station manufacturers and in the Buffered HLL model project for e-buses in Bensheim, Hesse. In this project, the DC meter is integrated into a fast-charging station with an intermediate storage unit and measures all energy quantities in compliance with calibration law. Thanks to the buffer storage technology, e-buses can be supplied with energy as needed via a pantograph.