Struktura sa Kabinet ug mga Katangian sa Proseso sa Low-Voltage Switchgear

I. Paghigamit

Ang struktura sa cabinet ang pundokan sa low-voltage switchgear, kung sa diin ang teknolohiya sa paggawa sa cabinet ang pundokan sa tanang pundok. Isip structural enclosure, ang cabinet dili lang kinahanglan molihok sa functional integration sa iba't ibang electrical units (tulad sa standardized types, modular combinations, ug functional distribution), apan usab kini kinahanglan mobati sa inherent nga mga pangutana sa cabinet (tulad sa robustness, reliability, maong anyo, ug lisod sa pag-adjust). Tungod sa variation sa requirements sa struktura sa cabinet ug capabilities sa paggama sa iba't ibang producers, ang mga proseso sa paggama dili mahimong rigidly standardized. Apan, mayroon pay certain universally applicable ug critical nga teknikal nga characteristics sa paggama sa cabinet. Ang mga key features gibanggit sa ubos kasama sa selection sa struktura sa cabinet.

II. Struktura sa Cabinet ug Teknikal nga Characteristics

Ang struktura sa cabinet ug ang ilang proseso sa paggama makapili gamay pila sa structural form, connection methods, ug material selection.

1. Classification batas Structural Form

(1) Fixed-Type:

Kini nga disenyo nag-ensure sa reliable nga fixation sa bawat electrical component sa ilang designated position sa loob sa cabinet. Ang mga anyo sa cabinet tipikahanong cuboid (e.g., panel o box type), apan ang trapezoidal forms (e.g., console type) usab gisulti. Ang mga cabinets mao ang makapili arranged isip single units o sa rows.

Para maprotektahan ang dimensional ug geometric accuracy, ang components kasagaran assembled in stages—tipikahanong sa pagsugyot sa duha ka side panels o left-right sections, pagkatapos assemble sila sa full cabinet, o sa pagsugyot sa external dimensional requirements ug pagkaron sequential connecting internal components. Ang length sa parts nga naghimo sa edges sa cabinet kinahanglan precise (negative values nga tolerances) aron maprotektahan ang overall geometric dimensions ug external appearance. Para sa duha ka side panels, dili naay bulging sa gitas para moprotektahan ang proper alignment sa arrangement.

Gikan sa perspective sa installation, ang base surface dili naay sagging. Sa panahon sa alignment ug installation, level foundation importante, apan ang flatness sa foundation ug ang cabinet mismo adunay inherent nga tolerances. Sa panahon sa alignment, ang lateral deviations kinahanglan minimo ug dili naay accumulation, tungod kay ang accumulated errors mao ang maka-cause sa deformation sa cabinet, affect busbar connections, lead sa misaligned component installation, create stress concentration, ug even shorten ang lifespan sa electrical equipment. Busa, sa panahon sa alignment, ang highest foundation point ang dapat gamiton isip reference, ug ang subsequent units ang dapat gradually leveled ug extended. Kung ang base flatness ideal ug predictable, ang expansion gikan sa center outward usab makagamit aron uniform distribution sa accumulated errors.

Arong mas madali ang adjustment ug compensate sa tolerance accumulation, ang cabinet width tolerances kasagaran specified as negative values. Pagkahuman sa assembly sa tanang components sa cabinet, shaping mao ang required aron maprotektahan ang dimensional ug geometric requirements. Para sa standardized o high-volume cabinet production, appropriate jigs ug fixtures dapat fully considered aron maprotektahan ang structural consistency. Ang fixture’s reference surface kasagaran ang cabinet base, ug ang positioning blocks sa loob sa fixture dapat arranged aron easy access ug operation. Ang external doors ug similar parts, prone sa deformation sa panahon sa transport ug installation, kasagaran adjusted uniformly sa final installation.

(2) Withdrawable (Drawer-Type):

Ang withdrawable switchgear consist sa fixed cabinet body ug removable unit nga adunay main electrical components tulad sa circuit breakers. Ang removable unit kinahanglan easy to handle sa panahon sa insertion ug withdrawal, reliably positioned sa panahon sa installation, ug interchangeable sa other units sa same type ug specification. Ang cabinet portion sa withdrawable switchgear manufactured similarly sa fixed cabinets. Apan, tungod sa interchangeability requirements, ang cabinet kinahanglan higher precision, ug related structural parts kinahanglan allow sufficient adjustment.

Ang manufacturing characteristics sa withdrawable low-voltage switchgear: (1) ang fixed ug movable parts must share a common reference datum; (2) related components must be adjusted to optimal positions using dedicated standard tooling, including standard cabinet frames and standard drawers; (3) critical dimensions must not exceed allowable tolerances; (4) interchangeability of identical drawer types and specifications must be reliable.

2. Classification batas Connection Method

(1) Welded Construction:

Ang advantages include ease of processing, high strength, ug reliability. Ang disadvantages mao ang large tolerances, susceptibility sa deformation, difficulty sa adjustment, poor aesthetics, ug inability sa pre-plate workpieces. Additional, ang welding fixtures adunay specific requirements:

• High rigidity, dili easy affected sa workpiece deformation;

• Slightly larger sa nominal workpiece dimensions aron compensate sa post-weld shrinkage;

• Flat, simple, ug easy to operate, minimizing rotating mechanisms aron prevent damage;

• Supports must be carefully selected aron prevent weld corrosion ug allow for easy inspection ug adjustment, with anti-corrosion pads added where necessary.

Ang welding deformation occur tungod sa thermal expansion sa molecules sa weld zone, causing microscopic displacement sa cooling nga result sa residual stress. Aron mitigate deformation, shaping processes must be considered. Common methods include:

• Predicting deformation range through testing ug pre-deforming the workpiece sa opposite direction before welding;

• Correcting over-adjustment after welding;

• Hammering o pressing sa relatively contracted areas aron balance stresses;

• Heating sa relatively bulged areas after welding aron achieve uniform shrinkage;

• Performing overall heat treatment when necessary.

Additional, ang weld point selection, weld seam orientation, welding sequence, ug spot welding positioning all influence post-weld deformation. Proper handling can reduce deformation, though this depends on specific conditions.

(2) Fastener Connection:

Ang advantages include suitability sa pre-plated parts, ease of adjustment ug aesthetic finishing, standardized component design, pre-production inventory, ug small dimensional tolerances sa frame. Ang disadvantages mao ang lower strength compared sa welding, higher precision requirements sa components, ug relatively higher manufacturing costs. Ang fasteners typically standard parts, including common screws, nuts, rivets, blind rivets, adjustable clamp nuts, pre-tensioned pull nuts, ug self-tapping screws. Special-purpose fasteners (such as those used in many imported low-voltage cabinets) usab available.

Ang technological characteristics: Fixtures used for shaping, ug tooling for positioning. Pressure washers may be used as needed. Riveting usually requires pre-drilling, ug care must be taken to protect plating sa pre-plated parts. For components machined with precision CNC centers o dedicated equipment, if connection hole diameters maintain a slight clearance with fastener diameters, assembly can be completed without fixtures in a single step. For fastening guide ug positioning components, dedicated measuring tools should first establish position, followed by inspection with standard tooling.

(3) Hybrid Connection (Welding ug Fastening):

Kini nga method combines the advantages sa both above methods. Welding typically used sa cabinet connection points, while fasteners used sa variable or adjustable sections. Large cabinets difficult to plate after welding, so surfaces often painted. For outdoor cabinets made from pre-plated materials that require welding, the welded areas can be treated with thermal metal spraying.

3. Classification batas Component Material

(1) Sectional Materials:

Kini include angle steel, channel steel, special-shaped steel tubes, ug special channel steel. Components made of angle or channel steel typically joined by welding. During processing, connection ends must fit tightly with minimal gaps; otherwise, weld quality ug deformation will be affected. 

Special-shaped steel tubes can be connected by either welding or fasteners. Connection parts usually require dedicated fittings that must be strong ug precise; otherwise, cabinet appearance will be compromised. Using uniform special-shaped steel tubes with uniformly spaced (modular) holes ug standard connectors allows modular cabinet assembly, simplifying design, component preparation, ug production planning. However, this method involves many holes, most of which remain unused, ug limits spatial flexibility.

Manufacturing characteristics: Ensure universality ug precision of components ug connectors. The basic cabinet structure often reinforced with panels. Besides special-shaped steel tubes, C-shaped channels or ribbed rectangular tubes made from sheet steel also used. C-shaped channels suitable for plating, while ribbed rectangular tubes may rust after plating due to residual acid from pickling, so selection should be cautious.

(2) Sheet Metal Components (excluding C-channels ug ribbed rectangular tubes)

Kini can be formed entirely according sa requirements, without limitations from pre-formed profiles. This structural design involves higher engineering effort, but once standardized, variations are minimal. Main structural parts usually welded, while variable or adjustable areas use fasteners (e.g., low-voltage control boxes ug consoles).

Since sheet metal structures mostly welded ug formed in one piece, welding-induced shrinkage or bulging must be addressed. Welding points should be evenly spaced, weld seams smooth, post-weld shaping performed, edges straight, ug the middle of both sides must not protrude beyond the front ug rear edges. If internal partitions exist, they should be welded after the two sides properly shaped.

Console-type control cabinets best suited for sheet metal components. When multiple units arranged in a row, the tabletop should be aligned ug positioned only after the entire row in place.

III. Conclusion

As analyzed above, the selection of cabinet structures must be determined not only by the functional requirements of the switchgear but also by manufacturing process constraints. The level of manufacturing technology directly influences cabinet structural design ug material selection.