What is the meaning of the main transformer low-voltage side of the power supply

As for the transformer and said, the power side is the high-voltage side, the load side is the low-voltage side, for residential power customers, the power side refers to the property rights unit by the *** building unit is responsible for the review, the test of the whole is responsible for the power customer, the third point of difference is the power supply test, provide power supply at one end, while the load test, the use of power supply at the other end.