The direct field sensor: a mature solid state metering technology

The trend towards solid-state solutions in electricity metering is well established. Many technologies have become available each with its claim to special suitability for particular applications but none has yet established itself as the successor to the once-dominant Ferraris metering element. The reason for this is that Ferraris metering elements were widely applicable to the whole range of prevailing market needs, whether for simple single-rate domestic devices or for the most complex polyphase devices with capabilities for reactive energy measurement and impulsing outputs. No solid-state technology was able to offer the same universal flexibility, but a breakthrough in the development of a Hall-effect based transducer has changed this. The new technology is known as Vertical Hall and it overcomes the hitherto practical difficulties, namely temperature, linearity and offset problems, which have excluded it from metering applications in the past. The authors describe the Vertical Hall devices in particular the direct field sensor