SMS-YB□-12 pre-installed box-type substation (referred to as box change) is a compact set of high-voltage electrical equipment, power transformers, low-voltage electrical equipment, auxiliary equipment and their connecting parts. The electric device is mainly used to replace the traditional civil substation. It is suitable for the rated voltage 12/0.4kV three-phase AC system. It is used for receiving and distributing electric energy, especially suitable for industrial parks, residential quarters, commercial centers, public places, Use in airports, terminals, subways, hotels, schools and construction sites, mines, oil fields, etc.