Ferraris type electricity meter, contains rotor disc with reflector capable of asymmetric reflection in at least one direction

摘要

The rotor disc (1) is provided with at least one reflector (11) with asymmetrically varying reflection properties in at least one direction on one side. A control unit sends out a detection signal when it receives a signal from the reflected light sensor (5) significantly in excess of a stored reference value corresponding to the asymmetrically varying reflection properties. The meter contains a radiation source (4) for directing electromagnetic radiation against the rotor disc, a sensor for detecting the radiation reflected by the disc, and a control unit coupled to the radiation source and sensor.