D. WYE – DELTA: 4-Wire, 3-Phase Service
A B C N
H1 H2
H1 H2
H1 H2
X3
X1
X1
X3
X1
X3
Tank GND
Tank GND
Tank GND
X2
X2
X2
a b c n
Primary Wiring: With a WYE connected high- voltage side, the H1 terminal of each transformer is typically connected to a different phase of primary. The H2 terminals are connected and allowed to form a “floating neutral”. NOTE: Do not connect the H2 terminals to ground. Grounding the floating neutral can create over-voltages during a fault event that can damage the transformers. Also note, the H2 bus is considered an energized conductor. Secondary Wiring: This secondary connection supports both single-phase and three-phase loads. 240∆ /120 banks are popular due to their ability to serve multiple customer types from the same transformer bank: single-phase for customers with lighting and small motor loads, and three-phase for other customers who have
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