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Testing Energy Meters for Electromagnetic Compatibility

INTRODUCTION

Energy meters are used in every house and industry to measure the energy consumed. Large energy consumers want better data to make energy management decisions, and utilities need more data to improve their services. The thrust, therefore, is for more and more value-added features, along with compactness of size. 

The increase in the use of electronics and microprocessors has led to the development of electronic meters with features like remote sensing, Internet connectivity, LCD displays for active as well as reactive energy, recording of tampering events with date and time, multi-tariff billing, maximum demand and many other power quality monitoring features.

These advances in technology have given rise to the problem of electromagnetic interference (EMI). The circuitry/subassemblies of equipment in use can emit electromagnetic energy, which can affect the performance and reliability of both the nearby equipment (i.e. intersystem interference) and the performance of the sensitive circuit within it (i.e. intrasystem interference).

Accurate billing of the power consumed is important to both utilities and consumers. It is necessary to ensure that meters function properly, particularly in the event of any EMI occurrence, which is a common feature. Events such as switching of inductive loads, electrostatic discharge, lightning, and the presence of telecom, radio and video broadcast signals will give rise to some type of EMI. It is thus essential to manufacture energy meters that are electromagnetically compatible – that is, they should be neither a source of EMI nor affected by any EMI.

This article outlines the various electromagnetic compatibility (EMC) tests according to International Electrotechnical Commission (IEC) standards, and some causes of and solutions to EMI.

NEED FOR ELECTRONIC ENERGY METERS

An electronic energy meter’s functionality and performance is superior to that of the traditional electromechanical energy meter. Electromechanical energy meters work on the Ferraris principle – they register energy on the basis of flux produced by voltage and current and integrate it through the mechanical movement of gears. These electromechanical energy meters have numerous drawbacks, such as lack of stability and accuracy drifts over long periods of time and with variations in the operating environment. Electronic energy meters, on the other hand, use electronic components and are capable of providing all the data needed by consumers and utilities in a reliable manner.