Application of switchgear ring network

When it comes to ring main units, they are gas insulated compact switchgear with a rated current of 630A and a short-circuit current of 20kA. The main functional units include load switches, load switch fuse combinations, circuit breakers, direct incoming lines, and metering cabinets. There are two forms of assembly: shared box and single cabinet. Different types of insulation include air insulation, gas insulation, solid insulation, etc.

RMU (Ring Main Unit), Ring Loop, Main Switch, Unit Unit. Ring main unit is a switch cabinet used for power supply in ring power grids. Ring main unit is a type of switch cabinet used in various applications, consisting of RING ring input and output, and MAIN main input and output cabinets, rather than cabinet type. A similar application method is MAIN-TIE-MAIN, with two incoming lines and one busbar.

The switchgear for this application can be air insulated withdrawable circuit breakers, fixed circuit breaker switchgear, or gas insulated switchgear.

In China, it has become a specific type of cabinet. Ring main unit is only used for secondary distribution systems, compact gas insulated load switch/fixed circuit breaker switchgear. 630A-20kA。 Due to the low current, compact and miniaturized switchgear is preferred.

With the application of new energy and data centers, the scope of ring network applications continues to expand, and the current continues to increase. The short-circuit current also increases significantly, such as the rated current reaching 4000A and the short-circuit and short-time withstand current reaching 40kA.

The ring network is no longer limited to power supply, such as in wind farms, where each wind turbine generates electricity and the power is concentrated together through a hand-in-hand ring network unit, and then transmitted to the grid through a booster station.

Data center power distribution, with increasing capacity, will adopt a ring network power supply method to ensure power supply reliability, distributing high-voltage electricity from the power grid to power modules.

The demand for remote control and other intelligent technologies has led to the use of circuit breaker solutions, such as three position isolation switches with fixed circuit breakers or handcart circuit breakers, instead of load switches or load switch fuse combinations in ring network applications.

According to the application environment requirements, air insulated or gas insulated switchgear shall be used. Because the current is greater than our general concept of a ring main unit, a high current switchgear is required. A typical use of inflatable cabinets is compact in size, such as 38kV 1250/2000A 31.5kA environmentally friendly gas insulated switchgear, which is compact in size, equivalent to 50% of the footprint of air insulated switchgear. The key is its small depth, which can be installed against the wall and is suitable for container installation.

As required by a certain data center, 38kV 1250A 31.5kA, air insulation, solid insulation, or environmentally friendly gas insulation can be used, with a width of less than or equal to 750mm and a depth of less than or equal to 1200mm. It should be connected and maintained in front of the cabinet.

It cannot be achieved using air insulation. Solid insulated special cabinet types are suitable, while environmentally friendly gas insulated switchgear is very suitable for ring network applications.

However, some applications do not require installation space and are sensitive to price and operational flexibility. Therefore, 38kV outdoor switchgear is more suitable. Three switchgear cabinets, including ring inlet, power module outlet, and ring outlet, are installed in a pad style with a width of 3258mm, depth of 3048mm, and height of 3100mm. The installation is simple and the operation and maintenance are convenient.