Product Introduction:
The RMU series ring main unit switchgear is a fully enclosed metal switchgear with SF6 gas insulation. This equipment is composed of load switch units, load switch-fuse combination electrical units, vacuum circuit breaker units, and busbar inlet units. It adopts a series of advanced technologies and materials, featuring excellent electrical and mechanical properties. It is less affected by the environment and climate, has a small size, is easy to install, operates conveniently, requires no maintenance, and has flexible combination methods. The clear and intuitive design ensures simple and direct operation. The feeder connection capacity is large, suitable for various connection systems.

Product Features: Operational safety
Through the following security measures, we can provide users with special security protection:
◆ Integrated three-position load switch
◆ The circuit breaker replaces the disconnect switch with a load switch, making it safer and more reliable
◆ The primary side is fully enclosed, providing protection against accidental contact
◆ Mechanical interlock meets the five-prevention requirements
◆ Live display can provide indication of live circuits entering and exiting the line

Reliable operation
The fully enclosed design seals all 10kV switches and busbar energized parts within an air box welded by 3mm stainless steel plates; equipped with silicone rubber cable plugs to achieve full insulation and sealing of the cable heads, thus not affected by external environmental factors such as dust, moisture, and small animals
◆ Spring energy storage operating mechanism, which can be operated manually or electrically
◆ Panel simulation wiring diagrams provide indication of switch positions
◆ The cabinet body is made of galvanized steel plates, with surface electrostatic spraying to enhance corrosion resistance
◆ Pressure gauge monitors the safe pressure range of SF6 gas inside the box Economy
◆ Maintenance-free
◆ Highly reliable
◆ Service life can reach 20 years

Flexible solution
◆ Multiple input methods, enabling left, right, top or forward connection
◆ Various combination methods, allowing arbitrary combination among units
◆ Using insulated busbars, enabling parallel connection in front-back or left-right
◆ Flexible design scheme Extensively applied

The outgoing line has a large capacity and occupies a small area, making it suitable for various application requirements.

Design Description:
The RMU series ring main switchgear is installed on a galvanized plate frame. The switch units are located in the SF6 gas box, which is made of corrosion-resistant and non-magnetic 3mm thick stainless steel plates. The SF6 gas box is a "sealed pressure system" and can operate for 20 years under normal working conditions. The normal working pressure of SF6 gas is 0.15 to 0.4 bar. The gas box is equipped with a pressure release device, which ensures that the gas can be released from the bottom or the rear in case of excessive pressure. The load switch of the switch unit adopts a coaxial rotating double-breakpoint method and is operated through the same operating hole in conjunction with the sliding plate, thus ensuring that the switch can only be in one of the three states at any given moment: "closed, opened, or grounded", completely avoiding misoperation. The operating mechanism of the switch is installed at the front of the gas box and is treated with special processes to prevent rusting, facilitating manual operation and maintenance, and enabling easy electric operation. It truly meets the requirements of the cable room for the cable connection room, which has a large space. The bushings are designed in a standard style and are compatible with all European standard cable plugs. Under normal circumstances, each load switch unit can connect 1 to 3 outgoing lines, and the special design type can connect 4 to 6 outgoing lines. The vacuum circuit breaker unit can connect 1 to 2 outgoing lines. The pressure release device is separated from the cable room by a metal plate. If the pressure in the gas box is too high, the explosion-proof membrane in the device will rupture to release the pressure. The cable connection uses international standard universal bushings (in compliance with DIN47636 standard or American standard), facilitating users to select the corresponding cable accessories. The T-shaped front and rear cable plugs are used for connection. The European-style bolt progressive tightening structure is adopted, and the connection between the front plug and the bushing uses an M16 bolt. The lightning arrester can be connected to the load switch unit and an additional T-shaped rear plug-in silicone rubber fully sealed metal oxide zinc lightning arrester can be installed. When there are many cable circuits and insufficient space, a π-shaped rear plug-in lightning arrester can be used.

The interlocking mechanism inside the switch can effectively prevent incorrect operation and ensure that the cable compartment can only be accessed when the switch is in the "grounded" state. It can also be equipped with a lock to be locked in different states. The auxiliary switch load switch and grounding switch can be configured according to needs to have auxiliary switches that can synchronously reflect the position status of the switch. The fuse RMU series switch fuses can be replaced directly and simply. The fuse is placed inside the insulating tube, which is located in the SF6 metal gas box. This design has the following advantages:

◆ The fuse cover and sealing device are in the weak electric field part
◆ There are no conductive substances that can adhere to the fuse assembly
◆ The part in SF6 gas is fully protected
◆ The fuse cover does not require an additional insulating spring energy storage operating mechanism and linkage tripping device to ensure that the load switch phases automatically open simultaneously when any phase of the fuse melts.

Operating conditions:
The RMU series switch cabinet is suitable for use within the temperature range of -40℃ to +50℃. The 10kV live parts are located in the SF6 sealed gas box. The silicone rubber plug realizes the connection between the cable and the switch, forming a fully insulated and fully sealed structure. The entire system is not affected by environmental factors such as moisture, dust, and corrosive gases. The SF6 gas box is made of stainless steel material to ensure that the switch is maintenance-free and has a long service life. The surface protection ring of the switchgear frame uses galvanized sheet, and the surface is electrostatically sprayed to prevent corrosion. The front operation panel of the cabinet has an electrostatic coating.

Standard coatings:
◆ Operation screen RAL7035 (white)
◆ Cable compartment door RAL7035 (white)
◆ Switch side plate RAL7035 (white)

Load Switch Unit C
This switch can be divided into single unit, single unit with double bushing outgoing line, two units, three units, four units, five units standard type and the type with side incoming bushing. It adopts a structure with a shared SF6 gas box, and there is no need for external connection of the busbar between each unit. Therefore, the structure is relatively simplified, easy to install and safer. Although it adopts an integrated gas box structure, each unit still has independent compartments. For units above six, insulation busbars are used for cabinet assembly to achieve parallel connection, which can be arranged front-back or left-right. The cabinet type is the standard type with busbar bushing on the upper side.

Standard configuration

◆ 630A busbar
◆ Three-position load/grounding switch
◆ Spring operating mechanism
◆ Position indication of load switch and grounding switch
◆ Outgoing line bushing arranged horizontally at the front
◆ Incoming line/matrix voltage indicator (single unit or matrix extended type)
◆ Outgoing line voltage indicator
◆ All switch functions can be controlled by adding padlocks on the panel
◆ Interlock between grounding switch and cable room door
◆ SF6 pressure gauge
◆ Grounding copper busbar
◆ Explosion-proof relief valve

Optional configurations

◆ Short-circuit and grounding fault indicator
◆ Measurement-type ring current transformer and ammeter
◆ Metering-type ring current transformer
◆ Switch position key lock
◆ Electric operating mechanism
◆ Reserve busbar expansion
◆ External busbar