App note from Infineon Technologies on 3D sensor used as anti-tampering devices on E-Meters, Link here (PDF)
This application note describes a possible realization of an anti-tampering solution in an Electricity Meter. With the new product family of the 3D Magnetic Sensor (TLV493D), Infineon offers an innovative solution for three-dimensional magnetic position sensing. By allowing a measurement of all three components of a magnetic field at the same time, it enables a multitude of applications with different ranges. Furthermore the integrated temperature sensor enables the application to compensate possible temperature-dependent magnetic field changes.
Just for the record they’re talking about electric power meters – household electricity meters …. not the woo-woo ohm meters that scientology use to sucker people in to their cult