Power Distribution Cabinet Complete Switchgear

Complete set switch cabinet is a kind of electrical equipment, outside first into the cabinet main control switch, then into the sub-control switch, each branch according to its needs to set. For example, instrument, automatic control, motor magnetic switch, all kinds of ac contactor, some also set high-pressure chamber and low-voltage chamber complete switchgear, with high voltage bus, such as power plant, some also set for the main equipment of low cycle load reduction. Complete switchgear is a combination of all parts involved in complete switchgear. Product categories According to the voltage classification, AC1000V and the following are usually referred to as low-voltage complete switchgear (such as PGL, GGD, GCK, GBD, MNS, etc.), AC1000V or more is referred to as high-voltage complete switchgear (such as gg-1a, XGN15, KYN48, etc.), and sometimes the voltage in the high-voltage cabinet with AC10kV is referred to as medium voltage cabinet (such as XGN15 10kV ring network cabinet). Classification by voltage waveform It is divided into: ac complete set switch cabinet, dc complete set switch cabinet Classification by internal structure Extraction complete set of switch cabinet (such as low-voltage extraction complete set of switch cabinet, low-voltage fixed separation complete set of switch cabinet, metal armor shifting complete set of switch cabinet, handcart cabinet) Classification by use Incoming cabinet, outgoing cabinet, measuring cabinet, compensation cabinet (capacitor cabinet), corner cabinet, bus cabinet In terms of structure (1) fixed: Can meet the electrical components reliably fixed in the cabinet to determine the position. Cabinet body appearance is cubic commonly, wait like screen type, box type, also have edge platform body to wait like desk. This kind of cabinet has single row, also have arrange. In order to assure cabinet body shape position size, often take each component step combination means, it is to form two pieces first commonly or left and right sides, form cabinet body again next, or satisfy appearance requirement first, connect cabinet body again in sequence support. The part length that forms ark body each edge must be correct (tolerance takes negative value), ability assures dimensions of each respect geometry, assure integral appearance requirement thereby. To cabinet body two flank, because consider to arrange need, cannot have bump phenomenon in the middle. In addition, from the point of view of installation, the bottom can not be caved in. Arrangement in the installation, the foundation level is a prerequisite, but dry degree of the whole and cabinet put oneself in another's position itself has certain error, in order to try to offset the horizontal difference, and don't cause difference accumulation, cabinet put oneself in another's position of deformation caused by the difference accumulation will, affect the busbar connection and produce components installed ectopic, stress concentration, even affecting the service life of electrical appliances. Therefore, the highest point of the foundation should be used as the reference point for installation, and then gradually spread forward. Under the condition that the dry integrity of the bottom surface is more ideal and predictable, the spreading mode from the middle to both sides can also be adopted to make the accumulated difference evenly distributed. In order to adjust easily and offset the accumulation of tolerance, the tolerance of cabinet body width is negative. After the combination of each component of cabinet body completes, inspect need to still answer to undertake plastic, in order to satisfy dimensional requirement of each part form position. To finalize the design or batch larger cabinet put oneself in another's position should be fully considered when loading fixture of employment, to ensure the correctness of structure and unified, fixture datum to take the bottom for completed, the positioning of the clamp arrangement will be subject to work out is convenient, the cabinet put oneself in another's position of the outer door wait for vulnerable to transport and install, generally for unified adjustment during installation. (2) extraction formula: Take out type is by fixed cabinet body and the movable device part that contains the main electric equipment element such as switch to be composed, can move a part to want portable when changing, after moving into the position wants reliable, and the drawer of same type and specification can be exchanged reliably, the cabinet body part in taking out type is processed method is similar to the cabinet body in stationary type basically. But as a result of interchange requirement, the accuracy of cabinet body must rise, the relevant part of the structure should have enough adjust quantity, as to movable device part, want to be able to shift already change, want to install main element reliably again, should have higher mechanical strength and higher precision so, its relevant part has enough adjust quantity even. The craft characteristic of manufacturing drawer-type low-voltage cabinet is :(1) fixed and movable two parts should have unified reference datum; (2) the relevant parts must be adjusted to the best position, and special standard tooling, including standard cabinet body and standard drawer, shall be applied during the adjustment; (3) the error of key dimensions shall not be out of tolerance; (4) the same type and specification of drawer interchangeability to be reliable. 2, from the connection mode (1) welding type: Its advantages are convenient processing, solid and reliable; Disadvantages are large error, easy to deformation, difficult to adjust, less beautiful, and the workpiece generally can not be pre-plated. In addition, the welding clamp has certain requirements: (1) good rigidity, will not be affected by the deformation of the workpiece; (2) the external size is slightly larger than the nominal size of the workpiece, which can offset the effect of shrinkage after welding; (3) smooth, simple, convenient operation, as far as possible to reduce the rotating mechanism, to avoid card damage; In order to prevent welding and easy maintenance adjustment, to choose a good workpiece support, support but also add anti-welding pad. The deformation of the workpiece after welding is caused by the stress caused by the expansion of hot molecules at the welding site, the micro-displacement caused by extrusion, and the failure to reset after cooling. In order to overcome the influence of deformation, the shaping process must be considered. The shaping methods are generally: (1) predict the deformation range of the workpiece through the test, force the workpiece to the opposite direction before welding deformation, in order to reach the predetermined size after welding; (2) after welding with a positive method to correct; (3) after the welding, the relative shrinkage part, and the stress balance; (4) after heating welding, relatively loose convex part, to achieve the same purpose of shrinkage and welding; (5) when necessary, the integral heat treatment of components. In addition, the choice of welding point, the direction of welding seam, the welding sequence and the spot welding positioning all have a certain influence on the post-welding deformation phenomenon. If properly handled, the deformation can be reduced, but this depends on the specific situation. (2) fastener connection: its advantages are suitable for the workpiece preplating, easy to change and adjust, easy to beautify processing, parts can be standardized design, and can be pre-production inventory, frame size error is small. The disadvantage is not as strong as welding, requiring high precision parts, processing costs relative to the rise. Fasteners are generally standard, the main types of conventional screws, nuts and rivets, rivets, as well as pre-tightening and adjustable clip nuts and pre-tightening nuts, and self-tapping screws. There are also special fastening screws (such as the introduction of foreign low - pressure cabinet mostly with special fastening screws). Process characteristics: shape with fixture, fixture positioning, and as needed with pressure washer; Riveting generally with a drill, and pre-plating to prevent the plating is damaged; For the components processed with precision machining center or special equipment, such as each connection aperture and fastener diameter can maintain a micro gap, can be assembled without fixture, forming; For fastening of guide and locating parts, special measuring tools should be used to locate them before testing with standard tooling. Structural characteristics of 1. MNS type low-voltage switchgear frame is a combination structure, and the basic skeleton is assembled from c-type steel. All structural parts of the cabinet are processed by galvanizing, through self-tapping locking screw or 8. The 8-grade hexagon bolts are firmly connected into the basic cabinet frame, and the door, partition, mounting bracket and bus function unit corresponding to the scheme change are assembled into a complete set of switch cabinet. The internal size, parts size and compartment size of the complete set of switch cabinet are all changed according to the modulus (E=25mm). 2. Each cabinet of MNS modular low-voltage switchgear is divided into three rooms, namely, horizontal bus room (in the rear of the cabinet), drawer room (in the front of the cabinet), cable room (in the lower part of the cabinet or the right side before the cabinet). The rooms are separated from each other by steel plates or high-strength flame-retardant plastic function boards, and the upper and lower drawers are separated by metal plates with vent holes, so as to effectively prevent accidents caused by the fault of switch elements caused by arc or bus short circuit with other lines. 3. The structural design of MNS type low-voltage switchgear can meet the requirements of various input and output line schemes: upward and downward, upward and downward, downward and downward. 4. Compact design: more functional units are accommodated in a smaller space. 5, the structure is versatile, flexible assembly, E=25mm as a module, the structure and extraction unit can be arbitrarily combined to meet the needs of the system design 7. The mechanical interlocking mechanism of various sizes of drawers conforms to the standard, with connection, test and separation of three obvious positions, which are safe and reliable. 8. Standard module design: standard units including protection, operation, conversion, control, adjustment, measurement and indication can be composed respectively, which can be assembled arbitrarily according to requirements. 9, the use of high strength flame retardant engineering plastic, effectively strengthen the protection of safety performance. 10. Generalization, high standardization and convenient assembly. With reliable quality assurance. 11. The cabinet body can be selected according to the different requirements of the working environment. 12. Continuity and reliability of equipment protection. 13. The maximum current-carrying capacity of MNS3.0 is 6300A, and the shock short-circuit current tolerance capacity of the main bus is 220kA. Common pitfalls 1.1 small air insulation gap For a long time, some manufacturers of high-voltage complete switchgear do not strictly implement the relevant technical standards, so that some of the current running 10kV high-voltage complete switchgear cabinet phase to phase, phase to ground air insulation gap between 100 ~ 125mm. As the electrical equipment with pure air insulation, the technical code for the design of high voltage distribution device clearly stipulates that the minimum gap of pure air insulation in 10kV system is 125mm. It can be seen from the results of ac withstand test and combined with the accident analysis that the minimum air insulation gap between phase and phase and phase to the ground of charged body in the 10kV high-voltage switchgear set is lower than 125mm and the capacity of the accident occurs. 1.2 poor insulation performance of supporting accessories China's 10kV high-voltage switchgear manufacturers are many, some manufacturers in order to reduce the cost, the use of low insulation level of the supporting accessories, resulting in the whole set of switchgear pollution lightning pressure reduction, not up to the rated standard requirements. According to the "6 ~ 10kV high voltage complete switchgear selection principle", and combined with the actual operation experience, the author believes that the surface insulation creepage specific distance of the accessories of 10kV high voltage complete switchgear should not be lower than the following requirements: porcelain insulation piece 18mm/kV, organic insulation piece 20mm/kV. 1.3 when using composite insulation, air gap should not be ignored Some 10kV high-voltage switchgear sets are equipped with partitions made of insulating materials to form the composite insulation mode of electrified body -- air gap -- insulating partition -- grounding body. From the actual situation, when using this kind of composite insulation, the air gap cannot be ignored. The minimum air gap is not less than 30mm, otherwise it is easy to cause insulation accidents. 1.4 poor operating environment and low maintenance quality Generally speaking, the operating environment of 10kV high-voltage switchgear sets is poor. It is often invaded by such things as dust, smoke and steam, so that the surface of the insulation layer is corroded and conductive substances are generated, forming insulation defects. Still have individual complete set switch cabinet to use unit, do not pay attention to the overhaul of equipment, maintenance, cannot discover and eliminate all sorts of insulation defect in time, cause the occurrence of insulation accident eventually. Two Suggestions 1. The design and manufacturing department of complete set of 10kV high-voltage switchgear shall strictly implement the relevant insulation standards and close the insulation clearance and quality of accessories. 2. The unit that USES the complete set of 10kV high-voltage switchgear must carry out ac withstand test before the equipment is put into operation. If the test results do not conform to the relevant provisions of the preventive test regulations, it shall resolutely return the equipment; For the complete set of 10kV high-voltage switchgear in operation, the maintenance and overhaul work should be done adequately, and the operation environment should be improved as far as possible.