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To The Electrical Industry,

Recently & more than once, we have been asked the question “can a standard step down dry type transformer (<600V) be reverse connected in lieu of using a step up transformer. For example, can a 480V, 3Ř  Δ to 208Y/120V, 3Ř transformer be connected as a 208Y/120V, 3Ř primary to 480V, 3Ř  Δ secondary”. We have researched this issue & have provided the following links & pdf file to help educate us all. The pdf file has bookmarks, & includes excerpts from the NEC, IEEE, Square D & ACME. This file & these links are not necessarily our opinion, but are offered as educational material only. We have also embedded a link to a very informative website regarding transformers, which also links to many other transformer sites. Also, we submitted this question to Mike Holt’s forum, & have embedded links to these forums. We have found this issue to be quite interesting, & we hope you enjoy.


delta xfmr1.pdf




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