Metering of symmetrical components

CONTENTS of previous publications on metering of symmetrical components have been confined to the components of current and voltage in 3-phase 3-wire systems. This paper discusses the method of metering the positive and negative sequence power and energy in 3-phase 3-wire systems, and positive, negative, and zero sequence power and energy in 3-phase 4-wire systems. Networks are described which make it possible to meter these components simultaneously and separately. Tables are included showing the location and number of instrument transformers required for each network. Equations involving the design of the impedances of the metering systems are given.