Generally speaking, from power generation, power supply to electricity consumption, it needs to go through 3 to 5 times of voltage transformation process, and regulator itself will produce large active power loss and reactive power consumption. isolation transformer is mainly composed of iron loss and copper loss. 

The iron loss of the transformer is proportional to the square of the grid operating voltage. stabilized power supply is basically stable due to the system operating voltage, so the change in iron loss is very small. It is called constant loss and is represented ; the copper loss of the transformer is proportional to the square of the current in the winding and inversely proportional to the square of the operating voltage, so it is called variable loss and is represented.