Evaluation of the damages in three-phase watt-hour induction meters after external high magnetic field exposition

The exposure of the high external magnetic field has disadvantageous influence on the electric energy meters. In the article, the typical damage of the braking magnets as the effect of external high magnetic field exposition is presented. The evaluation methods of the magnetic flux asymmetry and the calculation of the meter error have been included in a general discussion. The authors paid their attention on the statistical classification methods. As the results of discussion, based on the studies on numerous objects exposed to the high magnetic field, the classes of the breakdown have been determined. The defect identification and its assignment in the probability groups allows to evaluate the actual state of the energy meter and explain the last history of interaction with the strong magnetic field.