Not least as a result of the new German Energy Collection Act, electricity metering in conformity with calibration law has gained in relevance. In recent weeks, we have repeatedly received customer enquiries regarding so-called electricity measurement in conformity with calibration law. This type of measurement is required by the authorities in certain constellations, which are characterised by a special duty of proof and accountability. For example, it is required for the measurement of apportionment privileged electricity quantities that are passed on to third parties. But when is a measuring system compliant with calibration law?
A general answer to this question, which is valid for all federal states, is difficult to formulate here. The right contact persons are the measuring and calibration authorities responsible in the federal states. The BAFA also makes this clear in its information sheet on electricity meters and also points out that a measurement of electrical energy that does not conform to calibration law is to be classified as an administrative offence and is punished with heavy fines by the responsible measuring and calibration authorities.
Nevertheless it can be stated that a measurement that conforms to calibration law always consists of a conformity-weighted plug-in converter and a MID electricity meter. MID is an abbreviation for „Measuring Instruments Directive“. This refers to the „Directive 2004/22/EC of the European Parliament and of the Council of 31 March 2004 on measuring instruments“. If one of the two components is not assessed for conformity with MID, the measuring point may also not be in conformity with calibration law. Only in exceptional cases is it possible to exempt a measurement that conforms to calibration law. However, the possibility of this exemption must be clarified with the responsible calibration authority in individual cases. As a rule, a conformity assessment for current transformers does not expire. In the case of electricity meters, this must be replaced after eight years. The current transformers are exclusively plug-on transformers which, in contrast to the widespread folding transformers, have to be installed with increased effort.
A current measurement conforming to calibration law always consists of a conformity-weighted current transformer and a MID electricity meter.
In certain situations, a so-called difference measurement appears to be useful. Differential measurement refers to the determination of a quantity of current that is determined by subtracting several other quantities of current. There is currently no clarity whether this procedure leads to a measurement that conforms to calibration law and it should always be enquired of the responsible measuring and calibration authorities. Here you will find an overview of the responsible authorities in the federal states: https://www.eichamt.de/
The following can therefore be said about the introductory question: A measuring point conforming to calibration law always consists of a conformity-weighted plug-on converter and an electricity meter that has been conformity-weighted according to MID. You should in any case obtain information from the measuring and calibration authority responsible for you about the requirements they place on a current measurement conforming to calibration law.