Differentia:
1. The central cabinet is a handcart type (movable) switchgear, such as the KYN28-12 (GZS1) high-voltage switchgear shell, while the ring main unit is a fixed switchgear cabinet body;
2. Carganda commutationes generali sunt universibus principibus anulis, dum circuit interruptores generale sunt in cabinetis centris;
3. Different purposes, the central cabinet is usually referred to as KYN28 cabinet, a handcart type high-voltage switchgear, which is generally used to maintain the back-end transformer or other high-voltage loads. The ring main unit is primarily used for high-voltage power distribution, dividing one or two high-voltage power sources into multiple high-voltage power output lines; The central cabinet is primarily used for high-voltage load maintenance. There are two types of ring main unit cabinets: air insulated and fully enclosed gas filled cabinets. Air insulated cabinets use ordinary SF6 load switches connected through copper bars to form a system, while fully enclosed gas filled cabinets have dedicated connection devices for power input and output lines. The connection between cabinets is in a intact gas chamber filled with SF6 gas.