High voltage ring network cabinet is to improve the reliability of power supply, so that users can get power from two directions, usually connecting the power supply network into a ring. This power supply mode is called ring network power supply for short. In the AC 10kV power distribution system such as port and high-rise building, because the load capacity is not large, the high-voltage circuit is usually controlled by load switch or vacuum contactor, and equipped with high-voltage fuse protection. This system usually uses ring network for power supply, and the high-voltage switchgear used is commonly called ring network cabinet. In addition to the power supply to the substation, the high-voltage bus of the ring network cabinet shall pass through the through current of the ring power supply network (that is, the current supplied to the adjacent substation through the bus of the substation). Therefore, the cross section of the high-voltage bus of the ring network cabinet shall be selected according to the sum of the load current of the substation and the through current of the ring network.

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There are many kinds of ring main cabinets, such as hk-10, mkh-10, 8dh-10, xgn-15 and sm6 series.

Ring network cabinet is a set of high-voltage switchgear installed in the steel plate metal cabinet or made into the electrical equipment of assembling the interval ring network power supply unit. The core part of the cabinet is load switch and fuse, which has the advantages of simple structure, small volume, low price, improving power supply parameters and performance, and power supply safety, etc. It is widely used in power distribution stations and box type substations of load centers such as urban residential areas, high-rise buildings, large public buildings, factories and enterprises.

The ring network cabinet is generally divided into air insulation, solid insulation and SF6 insulation. It is used for opening and closing load current, breaking short-circuit current and transformer no-load current, charging current of certain distance overhead line and cable line, controlling and protecting. It is an important switchgear for ring network power supply and terminal power supply. In the cabinet, the load switch with air insulation mainly includes gas generation type, air pressure type and vacuum type. The load switch with SF6 insulation is SF6 type. Because SF6 gas is enclosed in the shell, the partition fracture formed by it is not visible. The load switch in the ring network cabinet generally requires three positions, that is, to cut off the load, to isolate the circuit and to be grounded. Gas producing type, air pressure type and SF6 type load switch are easy to realize three positions, while vacuum arc extinguishing type can only be disconnected and cannot be isolated, so in general, an isolation switch is added in front of the load switch in the vacuum load ring network switch cabinet to form the isolation fracture.