Design of a high-precision energy meter according to the Measuring Instruments Directive

Abstract: This thesis investigates how an energy meter should be constructed in order to apply to the Measurement Instrument Directive. The measuring instrument directive is a statutory industry standard. All meters used for billing purposes must abide by this standard. Multiple systems were investigated in order to find the optimal system according to the agreed upon demands. Each system is presented individually and need to be able to withstand 230V and 35A. The system which fulfills the demands the best is implemented. The choosen system is based around the M90E32AS and Atmega328pb IC:s from Microchip. The sensors used are current transformers and voltage dividers. The M90E32AS samples data from the sensors and forwards it to the Atmega328pb where they can be read by a computer. Communication is conducted via SPI (Serial Peripheral Interface). Isolation is needed to provide protection to low voltage components and other equipment. Because of this the transformers and optocouplers are used. The end result is a functioning energy meter. It measures voltage and current in a satisfying way with a very small margin om error. According to the test made regarding energymetering the measurement error is just above 1%. This is a bigger error than what was wanted but the tests are not very precise and the error is probably smaller in reality.