If the current is measured via two or more current transformers (e.g. two transformers) and the total consumption is to be recorded, the secondary signals of the individual current transformer can be added together with the aid of summation current transformers. This allows the total consumption to be recorded using just one measuring instrument. A standardized measuring signal is available at the output of the summation current transformer. In addition to adding the input currents, the sum is also divided by the number of summands (number of inputs).