IEEE - ANSI C57.91
Guide For Loading Mineral-Oil-Immersed Overhead And Pad-Mounted Distribution Transformers Rated 500 KVA And Less With 65 Degrees C or 55 Degrees C Average Winding Rise
| Organization: | IEEE |
| Publication Date: | 31 July 1981 |
| Status: | inactive |
| Page Count: | 26 |
scope:
This guide covers general recommendations for loading 65 "C rise mineral-oilimmersed overhead and pad-mounted distribution transformers described in American National Standards and rated 500 kVA and less. (For transformers rated 501 kVA and larger, see ANSI/IEEE C57.92-1981, [31') Recommendations for 55 "C rise transformers are included in this guide because a substantial percentage of these transformers are still in service.
Loading recommendations in tabular form are contained in Section 5 of this guide. A method to establish winding temperature and loss of life by nomographs is also given in Section 5.
The method used for the calculation of the loading guide tables in Section 5 is given in Section 6 of this guide.
The recommendations of this guide are based on winding hottest-spot calculations only. Other factors such as listed in 3.6.1 may limit the permissible load to lower values.
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