Ring main unit is a switch cabinet used for urban ring main power supply. The core part adopts load switch and fuse;
Ring main unit is generally divided into air insulation and SF6 gas insulation, which are used for diverting and merging load currents. SF6 gas insulated cabinets are known as inflatable cabinets.
Ring main unit name data from life, inflatable cabinet refers to the switch arc extinguishing medium.
These two definitions are different, but the general ring main unit more use inflatables, will produce concept confusion.
In fact, as long as the structure of ring main power supply can be formed, whether it is inflatable cabinet, or such as the middle cabinet, it can be called ring main unit.
Inflating cabinet is to seal high voltage control components such as bus, circuit breaker, isolating switch, transformer and so on in the shell filled with a lower working pressure (0.1 ~ 0.5mpa)sf6 or some other gases. Inflating cabinets bring many corporate advantages to the society, and their biggest competitive advantage is not affected by any external economic environment, such as condensation, dirt, small animals and chemical research substances. Another important advantage is that we use data compression gas insulation (such as sf6, n, or air), which facilitates the continuous development towards miniaturization. The performance of the inflatable cabinet has good oil-free switch technology, especially the vacuum system switch without maintenance or less maintenance, which greatly reduces the workload of management maintenance and maintenance personnel.
The rated current of the ring main unit is not large, so the high voltage switch of the ring main unit generally adopts a simple high voltage load switch with high voltage fuse, rather than a complex circuit breaker. That is to say, the high voltage switch in the ring cabinet is generally a load switch. The ring cabinet uses a combined load switch to run normal current and a fuse to cut short circuit current to replace the circuit breaker. Of course, this can only be limited to a certain capacity. The switchgear can also be used in the distribution system without loop main structure.
There are many kinds of central cabinets, which can be divided into import and export line switch cabinets, metering cabinets, transformer cabinets, old transformer cabinets, etc., while ring network cabinets mainly contact the switch cabinet, and the protection device sends out signals, resulting in switch action tripped and power cut off. Vs1 vacuum switch cabinet is usually used in cabinets, while ring network cabinets generally do not have protection devices. In the event of an accident, the fuses installed in the cabinet could overheat and cut the circuit, cutting off the user's internal optional AC high voltage load switch - fuse combiner or sulfur hexafluoride.