IEEE Std 1668-2014 pdf download – lEEE Trial-Use Recommended Practice for Voltage Sag and Short Interruption Ride-Through Testing for End-Use Electrical Equipment Rated Less than 1000 V.
One of the more predominant power quality events is the voltage sag, which is a reduction in the rms voltage magnitude below a given threshold* lasting typically from several cycles to several seconds’. It is widely known that voltage sags can have a strong impact on high-tech industries. EPRI has reported that a single voltage sag can cost manufacturers from tens of thousands to as much as US S2M [B2]. Electrical and electronics equipment connected to electrical networks have varying degrees of sensitivity to voltage sags. This sensitivity is determined by two major factors: the design of the equipment and the physical characteristics of the voltage sag. The goal of this recommended practice is to present and recommend voltage-sag test levels and test methods that best represent actual voltage sags. The audiences for this recommended practice include: -一 The equipment owners who want to better understand the phenomena of voltage sags and specify voltage-sag immunity testing aimed at obtaining less sensitive electrical equipment resulting in improved rid-through for critical processes -System integrators or original equipment manufacturers (OEMs) who are designing and building electrical equipment and must therefore understand the electrical environment and the test methods that will be used to determine the immunity of their equipment 一The test engineers who want to properly evaluate individual electrical equipment, or processes involving a number of different equipment, against voltage sags to determine the immunity or robustness of the equipment under test (EUT)
These data-visualization methods and representations are useful to quickly review the information. They are especially useful in looking at events occurring at a site over an extended time period. This approach is widely adopted, and often equipment sensitivity curves are also displayed with the voltage sag data as shown in Figure 2. The solid line represents an example voltage sag level where a control component may shut down. As the legend states, of the 20 events seen over the study period, there were four events that were below the voltage sag sensitivity limit for this device. The simplified approach (worse phase only, max duration) does not help the end user to understand the true mechanics of the event. Such a simplified view can lead to misunderstanding regarding why one event of a certain magnitude and duration can cause an industrial process to shut down where another of a similar magnitude and duration does not. Therefore, a more detailed understanding of voltage-sag characteristics, as well as how these events occur, is required.