Records from DFRs vs. Records from microprocessor-based relays

Today the use of digital IEDs for protection, monitoring and recording systems brings questions about the management and analysis of fault and swing records. Basic questions include: “what is the difference in between records captured from DFRs versus relays?”, “do I need a DFR in my system, and why?”, and “is my fault information good enough for complete fault and disturbance evaluation?”. Quality recording data is available, and needs the proper tools to ensure that timely power system disturbance analysis can save money, avoid blackouts and result in a more reliable system. This paper overviews the importance of record data, and explores how it can benefit power system performance. We focus on the importance of record length, record resolution, the presence of harmonics, sample rates, and the ability to record in multiple points of the plant (enabling comparison of data by one centralized device, rather than independent analysis). We will show the difference in triggering methods, length of the pre- and post-trigger data, sampling rates, wide area event monitoring and cross triggering.