The main frame is made of 8MF open-type steel, with mounting holes of modulus 20mm and 100mm, and a diameter of 9.2mm on both sides of the steel profile.

There are two types of main frames: fully assembled and partially welded structures.

Each functional compartment is strictly separated, primarily divided into unit, busbar, and cable types, with each unit operating relatively independently.

The horizontal busbars are arranged in a flat configuration behind the frame to enhance their short-circuit current resistance.

Cables enter and exit vertically: according to a three-phase five-wire or three-phase four-wire system.

Each drawer represents a unit, with sizes categorized into one unit, two units, three units, half units, and quarter units, resulting in five size series, with rated current for each unit circuit at 630A and below. The size variation of the drawers is limited to height; their width and depth remain unchanged, allowing for interchangeable units of the same function.

Each cabinet can accommodate a maximum of 11 drawer units or 22 half units or 44 quarter units. Drawer units have clear markings for test and extraction positions, and they are equipped with mechanical interlocks.