NOTE: Some utilities require a “corner grounded” secondary to reference secondary voltages to ground. Other utilities allow ungrounded delta secondary. It does not matter which phase is grounded, just ensure only one secondary phase is grounded and that any loads are grounded on the same phase. kVA Rating: The kVA rating for this type of transformer bank is three times the individual transformer rating. Example. 3 – 25 kVA transformer will have a 75 kVA bank rating. Note: To minimize circulating currents, the three transformers used for this service should have matching
impedances as much as practical. Mismatched impedances may lead to overheating
due to circulating current and pre- mature failure of the transformers.
CAUTION: Hazardous voltages exist between all ungrounded X2 transformer bushings, service conductors, the neutral, and/or ground. Exercise caution when working near these transformer bushings.
Page 53
Made with FlippingBook - PDF hosting