kVA Rating:
The kVA ratings of each of the transformers in this bank may be derived from the following: 𝑇𝑇 𝑙𝑙𝑙𝑙𝑙𝑙ℎ𝑡𝑡 𝑡𝑡𝑡𝑡𝑡𝑡 = 1 𝜙𝜙 𝑘𝑘𝑘𝑘𝑘𝑘 +(0.66 𝑥𝑥 3 𝜙𝜙 𝑘𝑘𝑘𝑘𝑘𝑘 ) 𝑇𝑇 𝑝𝑝𝑝𝑝𝑝𝑝 𝑝𝑝𝑝𝑝 = 0.66 𝑥𝑥 3 𝜙𝜙 𝑘𝑘𝑘𝑘𝑘𝑘 Where: T lighting = center tapped transformer servicing the single-phase load. This transformer is commonly referred to as the Lighting transformer. T power = the remaining transformer serving three- phase load. This transformer is commonly referred to as the Power transformer. 1 𝜙𝜙 𝑘𝑘𝑘𝑘𝑘𝑘 = the total estimated single-phase load. 3 𝜙𝜙 𝑘𝑘𝑘𝑘𝑘𝑘 =the total estimated three-phase load. Notes: 1) An Open Delta transformer bank can only serve 87% of its rated capacity. 2) Two transformers of equal size can only support 58% of what a three-transformer delta bank can support.
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