At present, there are many types of high-voltage ring main unit products, such as HK-10, MKH-10, 8DH-10, XGN-15, and SM6 series.
A high voltage ring main unit is an electrical equipment consisting of a set of high voltage switchgear installed inside a steel plate metal cabinet or assembled into a spaced ring power supply unit. Its core part uses load switches and fuses, and has the advantages of simple structure, small size, low price, improved power supply parameters and performance, and power supply safety. It is widely used in distribution stations and box type substations of load centers such as urban residential areas, high-rise buildings, large public buildings, factories and enterprises.
High voltage ring main unit is generally divided into three types: air insulation, solid insulation, and SF6 insulation. It is used for switching load current, breaking short-circuit current, transformer no-load current, charging current of overhead lines and cable lines at a certain distance, and plays a control and protection role. It is an important switch equipment for ring network power supply and terminal power supply. In the cabinet, the load switches equipped with air insulation mainly include gas production type, pressure type, and vacuum type. The load switches equipped with SF6 insulation are SF6 type. Due to the SF6 gas being enclosed in the shell, the partition formed by it is not visible. The load switch in the high-voltage ring main unit generally requires three positions, namely cutting off the load, isolating the circuit, and possibly relying on grounding. Gas producing, compressed, and SF6 load switches are easy to achieve three positions, while vacuum arc extinguishing switches can only be disconnected and cannot be isolated. Therefore, in general, a vacuum load ring main switch cabinet is equipped with an isolation switch in front of the load switch to form an isolation break.