The single phase transformer refers to the transformer with its primary and secondary winding being single phase winding. Unipolar switching power supply refers to the monopole output, that is, only positive and negative output.
There are two joints on the high-voltage side while three on the low-voltage side. They are: two input joints on the high-voltage side and three output joints on the low-voltage side.
If it is to supply the low-voltage electricity for civil use (220V lighting and domestic appliances), an earth terminal is necessary. The transformers of three low-voltage output terminals are mostly designed for rural areas where the load is scattered and the power consumption is not too large. Applying symmetrical double output on low-voltage side is beneficial to reduce the loss of lines which is distributed uniformly with the load. Either of the two output ends should be grounded.
The single phase transformer also has connecting groups.
Since the original side of a single-phase transformer is connected by the same magnetic flow, there is a relative polarity relationship. Those who have the same polarity are called dotted ends, while those with different polarity are called synonym ends.
Mark the the primary and secondary winding of dotted ends as head or end (AX、ax) , then the electric potential of the two sides are identical and the connecting group is I/I-12. If the primary and secondary winding of synonym ends are marked as head or end (AX、ax) , the electric potential will be opposite and the connecting group is I/I-6.