split-type and common box type ring network cabinet, with the high level of manufacturing, the power supply department of the ring network cabinet requirements, so the split ring network cabinet used more and more.
Split type, ring network cabinet in full accordance with the switchgear form of design and production, that is, each unit is an independent individual, individual with the same cabinet between the external connections, such as bus connecting bushings, grounding rows, secondary routing holes as well as inter-cabinet connection holes and so on.
Split benefits, individual cabinets, can be combined according to the needs of the project, the number of cabinets can be a lot, such as 8 to 12 units, can be equipped with metering cabinets, air metering cabinet units and other functional units can be seamlessly spliced together. A cabinet failure, only need to replace this one, without the need to replace all the cabinets. The switchgear cabinet has high overall strength, a small air box, little deformation, and little impact from high altitude applications and other applications.
The disadvantage is the high cost, site installation workload, there are also factories 2 ~ 5 units spliced to complete the overall transport equipment capacity. Single cabinet size compact, small width, assembly difficulties.
The so-called common box type, that is, all functional units, that is, ring network cabinet needs load switch unit, isolation and grounding three-station + vacuum circuit breaker (bus-side isolation or line-side isolation) unit, load switch fuse combination appliance unit, direct inlet unit, etc., according to the application of the corresponding functional units sealed inside an air box, such as two load switch as ring in, ring out, two combination appliance as transformer outlet etc. Three to six units are sealed in a common air box.
The main busbars of the common box are connected inside the air box without additional insulation, no main busbars need to be connected for on-site installation, and the earth connections between the units are pre-connected. Manipulator and its operator interface panel can be isolated through the gas box outside the partition, there is no isolation, through the casing as the outlet cable connected to the unit of the metal partition to isolate each other, the instrumentation room is also a whole, the necessary separation can be, the installation of components to share the space, the overall simplicity and convenience, that is to say, the less the workload of the field installation, the more safe and reliable products.
Common box type ring network cabinet of a problem is the strength of the gas box, the big box lack of reasonable reinforcement design, it will be swollen belly, swollen belly may bring several aspects of the problem.
1. The appearance is not beautiful, some products by adding a cover plate form blocking the gas box protruding part to beautiful.
2. Internal busbar connection, switch connection is affected by stress, small deformation, large impact on the isolation / load switch contacts on the neutral, which leads to shutdown, dynamic thermal stability failure. Therefore common box type ring network cabinet need to consider the deformation of the air box, high temperature thermal expansion, high altitude will lead to increased pressure difference between inside and outside the air box, this is the use of rigidly fixed connections will be a problem, the pressure will be forced to destroy the relatively weak connection, and the air box can not be inspected after sealing. General ring network cabinet switch unit fixed design for relatively weak large plane, will use floating connection, that is, to ensure that the key functional direction size is relatively fixed, and for the unimportant surface is not fixed, cantilevered connection, so that ensure that does not affect the performance, but also allows the gas box to have a certain degree of deformation.
3. Increase the risk of gas leakage, deformation means that the steel plate is raised, uneven, and all through the gas box mechanism connection, gas piping, pressure relief valves, etc. need to be completely sealed, seals require the installation of high surface flatness, any unevenness may lead to gas leakage. Also for gas tank welding, long time pulling can lead to gas leakage, for argon arc welding is ok, laser welding is high risk.
Excessive gas box enhancement is uneconomical, a moderate amount of deformation is allowed, also as a thermal expansion and contraction adjustment.
Many of the original design of only a common box type ring network cabinet, now also developed an expandable bus type, several switching units connected through the expansion bus, to achieve more than ten unit combinations, but also can be connected to air-insulated metering cabinet and other special units. That is, there is a common box type advantages, but also can be extended, replacement.