If two or more current transformers (for example, two transformers) are used for current measurements and total consumption is to be calculated, the subsignals from individual current transformers can be summed with the help of summing current transformers. This allows total consumption to be recorded using only one measuring instrument. The output of the summation current transformer is a standardized measurement signal. In addition to the increase in input current, the total is divided by the number of additions (the number of inputs).