China earthing transformer

The three phase Neutral earthing transformer is to provide an artificial neutral point for the system where the neutral point is not grounded, so that the grounding method of arc suppression coil or small resistance can be used to reduce the capacitance current to ground when the distribution network has a grounding short-circuit fault. , to improve the reliability of power supply of the power distribution system.
This type of transformer adopts Z-type wiring (or zigzag wiring). The difference from ordinary transformers is that each phase coil is divided into two groups and wound on the magnetic column of the phase in opposite directions. The advantage of this connection is that the zero-sequence magnetic flux can be The magnetic column circulates, and the zero-sequence magnetic flux of the ordinary transformer flows along the leakage magnetic circuit, so the zero-sequence impedance of the Z-type grounding transformer is very small (about 10Ω), while the ordinary transformer is much larger. According to the regulations, when using an ordinary transformer with an arc suppression coil, its capacity shall not exceed 20% of the transformer capacity. Z-type transformers can be equipped with arc suppression coils of 90% to 100% capacity. In addition to arc suppression coils, grounding transformers can also carry secondary loads, which can replace station transformers, thereby saving investment costs.