The function of ground transformer with arc suppression coil:
When the neutral point of Delta connection or Y connection can not be drawn out, the neutral point is used to add arc suppression coil or resistance. This kind of transformer adopts Z connection (or zigzag connection). The difference between this kind of transformer and ordinary transformer is that each phase coil is wound around two magnetic poles separately. The advantage of this connection is that zero sequence flux can flow along the magnetic pole.
The zero-sequence flux of ordinary transformer flows along the magnetic leakage circuit, so the zero-sequence impedance of Z-grounded transformer is very small (about 10), while that of ordinary transformer is much larger. According to the regulations, the capacity of ordinary transformer with arc suppression coil shall not exceed 20% of the transformer capacity. The Z-type transformer can be equipped with arc suppression coils of 90%-100% capacity, and the grounding transformer can be equipped with arc suppression coils as well as secondary loads, which can replace the used transformers, thus saving investment costs.