Neutral-Deriving Transformers for Grounding Low Voltage Systems with Delta-Connected Source Transformers

Recommendations are developed for selecting and connecting three single-phase transformers as a neutral-deriving transformer bank to ground a 480 V low-voltage power system supplied from a delta-connected source transformer. Assumptions made are that the system has no 277 V loads, and that the bank is used solely as a source of ground fault current.