Oil immersed transformer

Oil immersed grounding transformer

The function of a grounding transformer is to lead out the neutral point for adding an arc suppression coil when the system is connected in a delta or Y-shaped configuration. This transformer adopts a Z-type connection (also known as a zigzag connection), which is different from ordinary transformers in that each phase coil is wound on two magnetic columns. The advantage of this connection is that the zero sequence magnetic flux can flow along the magnetic columns, while the zero sequence magnetic flux of ordinary transformers flows along the leakage magnetic circuit. Therefore, the zero sequence impedance of a Z-type grounding transformer is very small (about 10 Ω), while that of ordinary transformers is much larger.