Failure to split and parallel the transformer windings will result in halving the kVA rating of the transformer. For 480Y/277V services, the transformers must be purchased with a single 277V winding. For the 416Y/240V service, three un-split 240V transformers will be used. Likewise, for the 830Y/480V service, three un-split 480V transformers will be utilized. NOTE: For three-wire self-contained metered services pulled from a WYE connected secondary transformer bank, standard 3-wire, Form 2S meters must not be used as they will register less than actual use. Rather for these type services, utilize a Form 12S or Form 25S meter. Both require a 5- terminal socket, not a 4-terminal socket. kVA Rating: This bank, especially with the 208Y/120V, serves both single and three-phase loads. The assumption is that any single-phase load is equally divided across each transformer. With this assumption, the kVA rating of the three individual transformers can be determined by the following equation: 𝑇𝑇 𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇 𝑇𝑇𝑇𝑇 𝑇𝑇 𝑘𝑘𝑘𝑘𝑘𝑘 = 1𝜙𝜙 𝑘𝑘𝑘𝑘𝑘𝑘+3𝜙𝜙 𝑘𝑘𝑘𝑘𝑘𝑘 3 For this transformer bank, individual transformer impedances do not need to be matched.
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