Switchgear profile versatility and accuracy
Profiles: profiles have angle steel channel steel, special steel pipe, special channel steel. Angle steel channel steel components are mostly connected by welding, and the connection ends must be matched during the processing with less gap, otherwise, the weld will be affected and the amount of deformation will be increased; the connection of special steel tube members can be either welded or tight For the connection of the firmware, the connection part is generally equipped with a special coupling piece. The coupling piece must be firm and correct, otherwise, it will affect the shape of the switchgear. Uniform special steel pipes are selected to be uniformly spaced (modulus) holes on the uniform surface, together with uniform universal coupling pieces, and the switchgear body is synthesized according to the uniform modular array, which is convenient for switchgear design, convenient for preparing components and production preparation, However, more holes are used and less used, and space utilization is limited.
The characteristic of the manufacturing process of this switchgear is to ensure the versatility and accuracy of components and couplings. The basic structure of the switchgear is often strengthened by the sealing plate. In addition to special steel pipes, the components of this switchgear are replaced by C-shaped channel steel or ribbed rectangular tubes made of steel plates. C-shaped channel steel is suitable for plating. The ribbed rectangular tubes are difficult to remove because of acid after pickling. It is easy to turn rust after plating, and it should be selected as appropriate.
Sheet metal components (not referring to the above-mentioned c-shaped channel steel and ribbed rectangular tube) can be completely shaped as required, without preset molding conditions. This type of structural design has a large workload, less variation after setting, and the structure is mainly welded. The mutations or adjustments are often connected by fasteners (such as low-voltage control boxes and consoles). Because the plate structure is often welded and formed at one time, it needs to be To overcome the effect of shrinkage or relative bulge of the board surface due to welding, the welding points should be evenly spaced, the weld seam should be flat, after welding, the shape should be straightened, the edges should be straight, and the middle parts on both sides should not protrude from the front and rear edges. When partitioning, it should be welded after handling both sides. Table-top control switchgears are best made of sheet metal. When multiple units are arranged, the tabletops should be adjusted after the overall arrangement.
1. In actual use, vacuum circuit breakers are often installed in metal switchgears to form high-voltage switchgear. In addition to circuit breakers, switchgear should also be equipped with isolation switches that act as isolation circuits and grounding switches that act as safety guarantees. Current transformers and voltage transformers for measurement or protection, surge arresters or RC absorbers for overvoltage protection, and high- and low-voltage switchgear shall also be installed with secondary circuit components and lines for relay protection, leading to cables or overhead Lines can enter the switchgear, making the high and low voltage switchgear a relatively independent combination of power distribution devices, switch stations in power plants, substations on transmission lines, and user terminal substations that receive electrical energy are widely used in various Kind of switchgear.
2. About 10 years ago, high- and low-voltage switchgear equipped with low-oil circuit breakers almost occupied a monopoly in the country, but with the rise of vacuum circuit breakers, low-oil high- and low-voltage switchgear gradually retreated second, since 1993 Since the request of "oilless transformation", this trend has been further fueled. Some provinces and cities have even banned the use of low-oil switches in the construction of urban power grids and important users, and old stations have gradually used vacuum Switch switchgear to replace less oil switch switchgear.
3. In summary, the current technical standards for high and low voltage switchgear in China are GB3906-91 3～35kV AC metal-enclosed switchgear; DL404-91 indoor AC high voltage switchgear order technical conditions, high and low voltage switchgear technology The parameters are similar to the technical parameters of the circuit breaker and depend on the parameters of the installed circuit breaker. The only difference is that the rated current of the high and low voltage switchgear is based on the minimum rating of each electrical component in the main circuit (such as an isolation switch, or current transformer) Current value.