Electricity meter protection circuit - using magnetic field recording element to indicate possible falsification of readings

摘要

The method detects if an electricity meter has been subjected to a strong magnetic field in order to falsify the reading of energy consumed. It consists of incorporating a permanently magnetic material in the plastic casing in such a way that a small mark dependent on the magnetisation of this material can be examined when the meter is read. Any change or obliteration of this mark can be observed either with a probe or magnifying apparatus, and this signifies previous application of a magnetic field.