Metrological supervision of electrical energy meters in substations up to 35 kV

Realization of metrological supervision is connected with several technical problems during testing of measuring instruments in the substations. Individual accuracy testing of electrical energy meters and instrument transformers could be done in the substations but, these testing require disconnecting or dismounting of controlled measuring instrument. This is comprehensive job which requires additional time and produces a significant financial loss. Measuring method, presented in the paper, enable accuracy testing of the entire measuring installation without disconnecting or dismounting of the single units. The proposed method requires specific measuring equipment accommodate for the special conditions in the plant. Analysis of the advantages and disadvantages of the proposed measuring method and measuring equipment is shown, especially measuring errors and metrological validity of such accuracy testing.