Transformer FAQ
What is a transformer vector group?
The vector group identifies winding connections, neutral availability and the phase displacement between transformer windings.
Direct answer
A transformer vector group uses letter and clock notation to describe whether windings are connected in delta, star or zigzag, whether a neutral is brought out, and the phase displacement between high-voltage and low-voltage sides. It affects grounding, harmonic behavior, protection, system compatibility and parallel operation.
Reading the notation
Letters identify the winding connection and lower-case notation normally refers to the lower-voltage winding. The clock number represents phase displacement in 30-degree increments.
Why it matters
The selected group determines neutral availability, zero-sequence paths and compatibility with the upstream and downstream system.
Parallel operation
Transformers intended for parallel operation generally require compatible vector groups, voltage ratios, tap settings and impedance values.
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