Second-generation DC meter series launched

Accurate energy measurement is crucial for providing reliable charging infrastructure and ensuring legally compliant billing. Measurement specialist Isabellenhütte introduces the IEM-DCR, the second generation of DC meters that fulfil these needs. With the completion of the certification, the meters are now available on the market.

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

The meters comprise separate display and sensor units, which simplifies their 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 15m 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 permits charging station operators to monitor their systems internally with high reliability. Additionally, 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 parameterisation, 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, whereas the two large meter variants, IEM-DCR-1000 and IEM-DCR-1500, offer four voltage channels. In the future, parameters can also be adjusted in the field to provide greater flexibility.

Three additional meter variants – IEM-DCS-125, IEM-DCS-1000, and IEM-DCS-1500 – consist only of the sensor unit. These are planned for markets where legally compliant energy reading is not needed. They are also suitable for customers developing their own display solutions or requiring 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.

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).

IEM-DCR meters are already being employed 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 incorporated 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 required via a pantograph.