The deployment of electronic energy meters has gained a great deal of momentum over the past several years. This is due to their two main advantages over the traditional electromechanical designs: improved accuracy and an expanded set of features. Current
microcontroller technology allows designers to build meters that are competitive in price with traditional devices while maintaining the required IEC 1036 Class 1 accuracy of 1% for domestic applications. Microcontrollers also allow the easy incorporation of
added features, such as rms voltage and current and peak demand metering, as local electric utility companies desire to implement them. In this application note, we will discuss the implementation of a basic watthour meter using PICmicro Flash microcontrollers. In the process, we will show how one ADC with a single sample-and-hold circuit can effectively measure both voltage and load current and maintain Class 1 accuracy.