The hottest SF6 fully insulated ring main cabinet

SF6 fully insulated ring cabinet and load switch

Abstract: SF6 fully insulated switchgear has the characteristics of fully enclosed, maintenance free, small size, excellent performance, safety and reliability, and is deeply welcomed by users. The ring cabinet has developed from the initial air insulated ring distribution unit to the compact SF6 ring distribution unit, and recently to the expandable SF6 fully insulated ring cabinet or multi circuit distribution cabinet, which has made great progress and development in the SF6 fully insulated switch technology

key words: SF6 insulated ring cabinet load switch

in the late 1990s, China's coastal areas with rapid economic development and some more developed inland areas widely adopted the switching station and switching station mode of ring junction line and multi circuit power distribution to optimize the power distribution structure of cables. SF6 fully insulated switchgear has the characteristics of fully enclosed, maintenance free, small size, excellent performance, safety and reliability, and is deeply welcomed by users. The ring cabinet has developed from the initial air insulated ring distribution unit to the compact SF6 ring distribution unit, and recently to the expandable SF6 fully insulated ring cabinet or multi circuit distribution cabinet, which has made great progress and development in the SF6 fully insulated switch technology. In particular, computer technology, electronic technology, sensing technology, optical fiber communication technology and other technologies are applied to ring cabinets or multi circuit distribution cabinets, making products more miniaturized and intelligent

□ technical characteristics of SF6 fully insulated ring cabinet or multi circuit power distribution cabinet

the technical characteristics of SF6 fully insulated ring cabinet or multi circuit power distribution cabinet are mainly shown in the following aspects:

(1) modular design, each unit module can be combined and expanded arbitrarily without charging and discharging, which is convenient for scheme combination and high-voltage measurement design, and has a wide range of applications. SF6 fully insulated circuit breaker incoming and outgoing cabinets (vacuum or SF6 arc extinguishing), load switch incoming and outgoing cabinets, buscouple cabinets, metering cabinets, load switch fuse combination electrical cabinets, and TV cabinets (with or without switches). The combination scheme can be a compact combination of single unit, two units, three units, four units, etc., providing a broad application prospect for SF6 fully insulated ring cabinets or multi circuit distribution cabinets

(2) the cabinet adopts armored structure. There are metal partitions between the bus room and the switch room, and between the switch room and the cable room. The protection grade of the primary part of the full insulation structure can reach IP67

(3) the load switch with three working positions is welded in the SF6 gas filled sealed stainless steel shell, which is the industry standard. It has very good air tightness and low air consumption, which can ensure no air leakage for 30 years, and meets the requirements of environmental protection. It is suitable for indoor and outdoor use with metal or non-metal shells, or placed in underground or semi underground substations

(4) the operating mechanism adopts corrosion-resistant metal, and the bearings of the rotating parts are self-lubricating design. The products are not affected by the environment, free from regular maintenance, and convenient to connect with the outside world, so that the operation work is small, the reliability is high, and the service life is longer

(5) the expansion bus adopts plug-in silicone rubber connectors, which are fully insulated and shielded to ensure conductive reliability and are not affected by the surrounding environment. The combination, connection and expansion are convenient, which is convenient for users or substation capacity expansion and transformation in the future

(6) the prefabricated silicon rubber insulated cable terminal is inserted in the front, which eliminates the disadvantages of inconvenient cable installation caused by small volume and narrow space of the load switch cabinet. It can be disassembled, quickly recovered and easily installed during maintenance; New semiconductor materials are used as the shielding layer on the outer surface, and the outer surface is grounded during operation, which is not affected by humidity, condensation, dust, dirt, etc., and has higher safety; Maintenance free; The appearance is diverse, novel and beautiful, and can be branched or connected in parallel; With flood prevention function, it can operate for a short time at 4.5m underwater

(7) in order to meet the requirements of distribution automation and improve the reliability of distribution, the new multi circuit distribution cabinet can be equipped with electric mechanism, TV and distribution control terminal unit as required, with three remote functions. It can realize remote operation status and fault monitoring of main components, remote meter reading, remote operation, etc

(8) cabinet miniaturization design, using a three position rotary load switch, effectively reducing the number of parts, and realizing the mechanical five prevention interlock. The vacuum circuit breaker is filled with SF6 gas insulation, making use of the respective advantages of vacuum arc extinguishing and SF6 gas insulation to make the overall structure more compact; The current limiting fuse is also developing towards miniaturization, large capacity, high breaking capacity and fast fusing. The combination of the two makes the cabinet smaller and smaller

(9) friendly operation interface ensures the safety of operators and maintenance personnel. The primary line analog single line diagram and analog display can display the internal state of the switch, making the operation simple, correct and safe

sf6 fully insulated load switch fuse combination apparatus

2.1 technical characteristics

sf6 load switch fuse combination apparatus in addition to the above technical characteristics, has the following characteristics: (1) SF6 load switch fuse combination apparatus with fully insulated structure, the fuse chamber is insulated and sealed by silicone rubber and insulator with mechanical interlocking, which is safe, reliable, flood proof, condensation proof, and the protection grade can reach IP67

(2) the fuse is installed on the support first, and then automatically led into the fuse chamber to ensure reliable fuse contact. The fuse is directly in contact with the left, middle and right three phases from the front, which is convenient for rapid replacement of the fuse. (3) With fuse overheat protection, the fuse will automatically trip in case of serious heating, and the hidden danger of transformer accidents will be found in time

(4) the fuse support is placed in SF6 gas and arranged horizontally, which greatly unifies the electric field and reduces the volume

(5) microcomputer can be configured to realize overcurrent protection. Transformer overcurrent fault is disconnected by load switch, and short-circuit fault is disconnected by fuse. The protection of transformer is more reasonable, which can replace circuit breaker to protect transformer of 1250kva and below in a full range

□ 2.2 application of protection transformer

load switch fuse combination protection transformer can limit the short-circuit current value, make the transformer free from sudden short-circuit fault current, and quickly cut off the internal short-circuit fault of the transformer within 10ms, so as to prevent the deformation and cracking of the transformer oil tank caused by the pressure rise caused by the internal arc, so that the transformer can be protected more reliably and reasonably. For the short-circuit at the end of the low-voltage side of the transformer, the high-voltage fuse is reasonably selected, and the short-circuit fault at the end of the low-voltage side is removed by the fuse at the high-voltage side, which can effectively protect the transformer

whether the structural form of SF6 load switch fuse combination or the structural form of circuit breaker can protect the transformer, but comparatively speaking, the load switch fuse combination has its unique side for transformer protection:

(1) the cost of SF6 load switch fuse combination is cheaper than the structural form of circuit breaker; If the price of circuit breaker is 100%, the price of SF6 load switch fuse combination is only 20%, and the price of imported SF6 load switch fuse combination is only about 1/3 compared with that of domestic circuit breaker cabinet

(2) compared with the circuit breaker, the SF6 load switch fuse combination has simple structure, low material consumption and high reliability. Its key manufacturing processes are shell welding and sealing technology and leak detection technology. The static tension transformer is protected more reliably and reasonably. For the short-circuit at the end of the low-voltage side of the transformer, the high-voltage fuse is reasonably selected, and the short-circuit fault at the end of the low-voltage side is removed by the fuse at the high-voltage side, which can effectively protect the transformer

whether the structural form of SF6 load switch fuse combination or the structural form of circuit breaker can protect the transformer, but comparatively speaking, the load switch fuse combination has its unique side for transformer protection:

(1) the cost of SF6 load switch fuse combination is cheaper than the structural form of circuit breaker; If the price of circuit breaker is 100%, the price of SF6 load switch fuse combination is only 20%, and the price of imported SF6 load switch fuse combination is only about 1/3 compared with that of domestic circuit breaker cabinet

(2) compared with the circuit breaker, the SF6 load switch fuse combination has simple structure, low material consumption and high reliability. Its key manufacturing processes are shell welding and sealing technology and leak detection technology

(3) according to the practice of some European power companies, the characteristics of the load switch fuse combination protection transformer are better than the circuit breaker. The breaking time of the circuit breaker with relay protection is more than 60ms, while the fuse can fuse quickly in 10ms when the current is high, which also limits the rise of short-circuit current and avoids the damage of sudden short-circuit to the transformer

(4) the SF6 load switch fuse combination has a relay protection device without power supply, which makes up for the defect that the fuse has no protection in the overcurrent part of the transformer. Compared with the relay protection device of the circuit breaker, the non power relay protection device of the load switch fuse combination does not need additional power supply, eliminating the TV cabinet or DC screen that provides power for the relay protection of the circuit breaker. The protection is simpler and the cost is cheaper. One load switch incoming line, one metering, and one load switch fuse combination electrical cabinet can protect the user's transformer without additional power supply. The traditional circuit breaker design scheme requires a circuit breaker incoming cabinet, a metering cabinet, a TV cabinet, and a circuit breaker outgoing cabinet. Both circuit breakers need relay protection and high-performance TA, and each switchgear needs a heater, so the cost and energy consumption are high, and there are many fault links

(540%) in actual operation, transformers with capacity of 1250kva and below account for the majority, and most of their rated current is below 72A, while the rated current of circuit breakers is generally designed in the range of 1250A ~ 3150A. It is obvious that the protection of transformers with capacity of 1250kva and below is a horse and cart, and the structure is not very reasonable. Using the load switch fuse combination structure, the high-voltage fuse protects the transformers under their respective jurisdiction, simplifies the coordination relationship with the superior circuit breaker, and makes debugging and maintenance much more convenient

conclusion

it is completely feasible for SF6 load switch fuse combination to replace the circuit breaker to protect the transformer of 1250kva and below. The hardness test is non-destructive. It has a comprehensive and reasonable protection for the transformer, and the cost is reasonable and the protection is simple. Under the same conditions, users have the ability to buy maintenance free products with higher performance. Therefore, the technical characteristics of SF6 fully insulated ring cabinet or multi circuit distribution cabinet are very obvious, and the fuse combination appliance of load switch factory is an ideal product for protecting distribution transformer. (end)