Ring Main Unit

The Ring Main Unit is a group of electrical equipment for transmission and distribution (high-voltage switchgear) installed in a metal or non-metal insulated cabinet or made into an assembling interval ring network power supply unit. Its core part adopts load switches and The fuse has the advantages of simple structure, small size, low price, can improve power supply parameters and performance, and power supply safety. It is widely used in distribution stations and box-type substations of load centers in urban residential districts, high-rise buildings, large public buildings, factories and enterprises.

Several kinds of net cabinets

HXGN-10 Type

(H-Ring Main Unit; X-box type; G-fixed type; N-indoor) The cabinet structure is assembled by bending and welding steel plates, and the protection level is IP2X. The upper part of the cabinet is the busbar room, and the instrument room is located at the front of the busbar room, separated by steel plates. The middle of the cabinet is the load switch room, and an insulating partition is arranged between the load switch and other components. For the cable entry and exit cabinet, the bottom of the cabinet is equipped with a removable cover plate; for the overhead entry and exit cabinet, the top of the cabinet can be equipped with bus ducts or shielding racks.

HXGN-10 Type

The HXGN-10 series air ring main unit has 15 schemes, of which scheme 01 is a load switch fuse cabinet; scheme 02 is a load switch cabinet, both of which are equipped with grounding switches; scheme 09 is a metering cabinet.

The shell of this series of ring network cabinet adopts steel plate bending and screw fastening assembly to form a metal fully enclosed structure. The cabinet body is composed of 4 uprights, upper cover, lower bottom, front panel, back panel, side panel, etc. The front of the load switch cabinet has two upper and lower doors fixed with screws; the front of the load switch fuse cabinet has 3 door panels. There is an observation window on the door to observe the position of the load switch and the grounding switch; the busbar connection between the cabinet and the cabinet is in the form of plum contact plugging, and the busbar is equipped with an insulating sheath. An instrument box can be added to the top of the cabinet according to user requirements.

The load switch installed in the ring network cabinet is gas-producing, oil-free and non-toxic; the manual and electric operating mechanism is a torsion spring energy storage mechanism, which has a simple structure and low operating force.

There are mechanical interlocking devices between the load switch, the grounding switch and the front panel. The operation relationship between them is as follows:

1) After the grounding switch is closed, the load switch cannot be operated, and the front panel can be opened;

2) After the grounding switch is opened, the load switch can be operated, but the front panel cannot be opened;

3) After the load switch is opened, the grounding switch can be operated and the front panel can be opened;

4) After the load switch is closed, the grounding switch cannot be operated and the front panel cannot be opened.

GE type
This is an imported model, which uses SF6 load switch. The operating mechanism is a spring energy storage type, with a quick closing and quick opening device. The opening mechanism is automatically stored by the spring during the closing action, and tripping is controlled (percussed) by the opening coil or HRC fuse.

SF6 is a load switch, the gas box is welded by stainless steel laser, completely airtight welding, there are no leaks and sealing gaskets; among them, 8DJ20 is a non-expandable common gas box structure; 8DH10 is an expandable type; it adopts a modular design to meet various requirements. The needs of terminal and ring network users. It has the advantages of compact structure, small footprint, and maintenance-free

Protective Device

On the basis of many years of application experience of domestic and foreign counterparts in the microcomputer protection device of the ring main unit, combined with the actual characteristics of the domestic integrated automation system, it is a high-tech power automation product that integrates protection, monitoring, control, communication and other functions. Ideal electrical unit for intelligent switchgear. The product has a built-in protection library composed of more than 20 standard protection programs, which has a complete and powerful collection function of the voltage, current analog quantity and switch quantity of the primary equipment (current measurement is realized by the protection CT)

Microcomputer protection
Since the ring main unit is subjected to high voltage, a protection device is required to protect the ring main unit. The use of microcomputer protection devices in the ring main unit is becoming more and more popular. Due to the small size and low cost of the ring main unit, a cost-effective and practical microcomputer protection device is required.

Scope of application: mainly applicable to user projects such as 10KV;

Protection unit: circuit, main transformer backup, motor, capacitor, reactor, backup automatic switch, PT, non-electricity;

Product appearance: The ultra-thin body within 100mm is especially suitable for cabinets such as ring network cabinets;

Product material: alloy shell, anti-electromagnetic interference test meets national standards;

Operating circuit: Without anti-jumping, it can be used in conjunction with various switches with anti-jumping;

Communication: optional with or without RS485 communication interface.

Application:

Ring main unit have not appeared for a long time, but they have been widely used. This is mainly due to the newly developed buildings of industrial enterprises and institutions. From the perspective of power supply and distribution, among them, small capacity is the majority. The distribution transformer generally does not exceed 1250KVA, long-term stable power supply, and high-voltage switches are not frequently operated. For this type of user, the performance of the ring main unit is not perfect, but it is adequate. With the large-scale urban construction, a large number of large-scale high-rise buildings have been erected, and the substations are often located downstairs. According to the fire protection requirements, the substation and distribution equipment must be “oil-free” and be used reasonably according to the construction area. , The transformer and distribution equipment should be “miniaturized”, so ring network cabinets or vacuum circuit breakers, dry-type transformers, and dry-type transformers have entered each building. The ring network cabinet has simple structure, reliable and safe operation, small maintenance, and low operating cost. Compared with switch cabinets equipped with circuit breakers, it has outstanding advantages. The ring main unit requires the load switch to have higher performance and smaller size. A new type of load switch came into being, which in turn led to the technological progress of the ring main unit. Today’s ring main unit is not only excellent in performance, but also serialized. , Which has expanded the scope of use of the ring network cabinet.