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Guide to transformer kVA ratings: How to determine what size transformer you need

ELSCO Transformers released a guide explaining how to calculate required kVA from electrical schematics by converting voltage and current into a transformer’s kVA power rating.
Across industries, facilities require reliable transformers to convert plant power into usable energy, and when equipment malfunctions, the transformer is often the culprit requiring correct kVA rating selection.
Use the single-phase formula V × I ÷ 1,000 to find 7.5 kVA from 150 V × 50 A, and multiply by 1.732 for three-phase transformers, producing 12.99 kVA.
When calculated kVA doesn't match market ratings, the guide advises selecting larger standard transformer sizes like 75 kVA for 52.5 kVA needs or ordering custom transformers.
Account for starting currents by applying a start factor of 125%, convert kW to kVA by dividing by 0.8, and consult professional transformer companies for specialized loads or large MVA systems.

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