This book is about standardizing the behaviour of Phasor Data Concentrators (PDCs)during data communication. PDCs can collect and process data from thousands of Phasor Measurement Units (PMUs) at rates of up to 60 frames/second. To successfully work at such high data rates, it is important that PMU and PDC communication is seamless. If PDCs are not processing and sending/receiving data correctly then their data cannot be used. It is important to determine what exactly is expected from a PDC under all conditions. For this reason, standards such as IEEE C37.118.2-2011 have been proposed to help make operation as uniform as possible. Unfortunately, the standards for PDCs are lacking and tend to only set up communication protocols. To help normalize PDCs, new requirements are developed and tested in this book so that they include all PDC operations; and give little room for discrepancy as to what a PDC should do in any given situation.