Sam Sciacca’s article, Assessing Vendor Claims on Time Resolution in IEDs alerts consulting specifying engineers to the vagaries of assessing vendors’ devices that accept time inputs because few vendors provide specifications that reflect absolute accuracy of the events record produced by each of their IEDs.
Opportunities abound for introducing errors in a system between the event and time-stamping in the device’s sequential event recorder, potentially leading to faulty analysis of an event. The higher the voltage, the greater accuracy that’s needed, raising the importance of assessing vendor claims. No standard currently exists for how IED vendors decide when an event has taken place. Filters and smoothing algorithms can result in different readings for the same waveform. These factors could cause multiple IEDs to show different times for the same waveform event, making precise analysis more difficult.
Besides providing guidance on the assessment of vendor claims in this article, a follow-on article provides insight into current standards work that could help consulting engineers and vendors to proceed in a uniform manner.
Read this and other articles by Sam on his blog, Insight on Power, published by CSE Magazine.
Sam Sciacca is an IEEE senior member and current chair of two IEEE working groups dealing with cyber-security for electric utilities: the Substations Working Group C1, which is working on P1686; and the Power System Relay Committee Working Group H13, which is working on PC37.240. Sciacca currently is CEO of SCS Consulting, LLC.