Watt-Hour Precision

As long as car manufacturers provide their customers with free electricity via their own charging infrastructures, kilowatt-hour precision in billing won’t be users’ top priority. No one looks a gift horse in the mouth, and no one looks too hard at prices or precise consumption data. But as soon as consumers have to pay for that energy, their behavior changes. Therefore, charging stations in Germany need meters that comply with calibration law. This applies not only to charging stations for e-vehicles, but also to network feed-in of solar energy and sub-metering contracts, such as are found in retail – wherever providers bill for energy, suitable meters need to be used. This is the only way to guarantee that the consumption billing complies with the law.

The basis for this is MID Directive 2014/32/EU. The so-called Measuring Instruments Directive (MID) is a European Union regulation intended to harmonize many aspects of legal metrology in all EU countries. It applies throughout the EU to all types of measuring instruments: from water meters, to electrical energy meters, to scales and taxi meters. The MID sets basic performance standards for measuring instruments, sets requirements that apply up to initial commissioning and governs manufacturers’ obligations. In addition to compliance with calibration law, WAGO’s energy meters with MID certification offer other benefits, which can be demonstrated by four example applications.

Infobox: WAGO Energy Meters (MID)

There are two basic versions of the energy meters suitable for consumption billing: direct meters for currents up to 65 A and transformer-operated meters for 1 A or 5 A signals, which allow measurement of currents up to several thousand amps. Users of both device variants benefit from a very narrow installation width: 72 mm (corresponding to four division units – DU) for the transformer-operated meters and only 35 mm (corresponding to two DU) for the direct measurement version. In addition to the values for active and reactive power, the energy meters also record the mains frequency, current, voltage and power for all phases. With the help of push-in CAGE CLAMP^® connection technology, all conductor types, e.g., fine-stranded conductors up to 25 mm², can be easily connected. In addition to safe wiring, this also saves time during installation. The devices have a wide variety of communication capabilities: Each has an M-Bus interface, a Modbus^® interface and two S0 interfaces. They can be operated either via touch-sensitive controls located under the illuminated full-format display or conveniently connected via Bluetooth^® using a free app.

Use in Charging Stations or Wallboxes

WAGO energy meters can be used for AC charging systems. The measured values are forwarded to the higher-level controller via the integrated interfaces – M-Bus, Modbus^® and two S₀ interfaces. This gives manufacturers of charging stations and wallboxes maximum flexibility, since all these interfaces can be operated with one universal MID meter series.

The Bluetooth^® interface is especially beneficial: Using the free “WAGO Energy Meter Configurator” app makes it easy to both read out data from the energy meters and configure them. Therefore, a default configuration can be easily transferred to each additional device. The energy meter has multiple configurable inputs and thus offers billing according to four different rates, which is of particular interest for use in charging infrastructure systems. For example, this can be used to bill energy separately for the company’s own vehicles and external vehicles.

Watt-Hour Precision

At a Glance:

Infobox: WAGO Energy Meters (MID)

Use in Charging Stations or Wallboxes