It is that time of year when people decide to toss out old documents and references that are seemingly cluttering their office environment. The reasoning behind this cleansing is that they already have the latest standards publication, which supersedes the old one. Although this may be true, I urge you to consider comparing the differences between the old and new publications before tossing the old one. The older version could contain information that provides more insight behind the standard than the new edition does.
For example, the latest IEEE Std 519, “IEEE Recommended Practices and Requirements for Harmonic Control in Electrical Power Systems,” was published in 2014 is only 29 pages long. It’s previous revision, published in 1992, is 101 pages long and features topics and chapters such as “Harmonic Generation,” “Analysis Methods,” and “Effects of Harmonics,” which either have been removed or condensed in the latest revision. I sometimes refer to the previous revision to obtain a better understanding of the harmonic limits table and how to apply it correctly. Some may argue that the information in the old publication is obsolete or outdated. This is accurate; hence, the need for a new revision. However, I have come to understand that the previous publication provides a little more background on the standard compared to the latest revision.
Having the latest revision allows you to be up to date on the standards and implement them accordingly. Unfortunately, the most recent publication sometimes only contains standards and omits the background on why they were established. It’s best to keep the old publications for reference, as these documents include the information on why these standards were needed in the first place.
