What do and what should digital revenue meters measure on distorted networks?

The paper deals with power formulations and energy considerations of nonsinusoidal systems. It is proved in the paper that the so-called distortion power has no physical meaning, and there is no need to take it into consideration. Simple patterns will underline these statements. Furthermore the novel IEC recommendation of digital energy meters to measure the active energy should be revised. There are different digital energy meters on the market. Results of laboratory tests are given on the accuracy of energy meters from different manufacturers.