Unsa ang mga komponente nga gisangpot sa disenyo sa medium-voltage ring network distribution switchgear?

Isipaglabay nga eksperto sa kalabutan sa disenyo sa sistema sa kuryente samtang mahimong matagal na ang panahon, gisulay nako ang teknolohikal nga pag-uli ug aplikasyon sa medium-voltage ring main distribution equipment. Isip sentral nga electrical device sa secondary distribution link sa sistema sa kuryente, ang disenyo ug performance sa maong equipment direktang may kalabutan sa safe ug stable nga operasyon sa power supply network. Sumala ang sumusunod nga professional analysis sa key design points sa ring main distribution equipment, gibinyagan sa industry standards ug engineering practices.

1. Overall Design Logic ug Architecture Planning

Ang disenyo sa ring main distribution switchgear kinahanglan maoos nga magkita sa operation requirements sa sistema sa kuryente ug national standards. Kinahanglan ipresyo ang usage scenarios, control objects, ug characteristics sa core electrical components aron makapagtukod og functional unit system. Ang primary switches mahimong circuit breakers o load switches, ug uban pa ang combined electrical appliances. Sa panahon sa disenyo, priority ang “load switch + fuse” combined circuit—kini usa ka komplikado nga structure ug makapakigbalaka alang sa pagtukod sa overall structure, layout, ug external dimensions sa equipment. Uban pang circuits sama sa pure load switch circuits, kinahanglan mogamit sa iyang mature design kon posible aron masayran ang standardization ug universality.

Sumala sa nabanggit, adunay daghan nga klase sa cabinets: load switch cabinets, combined electrical appliance cabinets, circuit breaker cabinets, multi-circuit cabinets, ug uban pa. Ang disenyo sa primary conductive circuit kinahanglan sistemadong pagbutangan sa tulo ka core elements: current-carrying capacity, electric force withstand capability, ug heat dissipation efficiency:

• Component Arrangement: Makakita nga pagbutang sa mga component aron siguraduhon nga ang moving contacts wala mobuntok sa panahon sa dynamic ug thermal stability tests, makapagtugot sa coordination sa mechanical ug electrical performance.

• Busbar Selection: Precise match sa circular o flat busbars sumala sa current-carrying capacity, reasonable control sa current density, ug balance sa current-carrying ug heat dissipation.

• Electrical Connection Optimization: Ang dynamic ug static contacts, sliding/fixed connections kinahanglan siguraduhon nga low contact resistance. Sa panahon sa paghubad sa iba nga metal conductors, gamiton ang proseso sama sa tinning ug silver plating aron maputli ang electrochemical corrosion ug maputli ang hidden danger sa contact failure.

Ang disenyo sa compartments sumala sa principle sa “safety first, process adaptation, ug convenient operation and maintenance”: ang protection level dili bayot sa IP3X, ang partition material (metal/non-metal) pilian basehan sa kinahanglan, ug pressure relief devices ug fault arc limiting measures configure—sa panahon sa internal arc faults, ang high-pressure gas makalubog pinaagi sa relief channel aron siguraduhon ang safety sa equipment ug personnel.

2. Multi-dimensional Considerations for Insulation Structure Design

Ang switchgear kinahanglan magbantay sa maximum operating voltage ug short-term overvoltage (atmospheric ug internal overvoltage) sa dugay. Ang insulation design kinahanglan comprehensive consideration sa factors sama sa environmental adaptability, material selection, structure optimization, ug process control:

(1) Electric Field Optimization ug Insulation Coordination

Ang shape sa conductors directly affects the electric field distribution inside the cabinet. Sa disenyo, gamiton ang rounded copper bars, round bar busbars, ug optimize ang shapes sa dynamic ug static contact seats, internal conductors, ug support electrodes aron maputli ang sharp points ug edges, making the electric field more uniform. With the help of finite element analysis software (such as ANSYS Maxwell), the weak insulation links can be accurately located. Through layout adjustment and structure optimization (such as the application of shielding technology), the electric field can be uniformized and the maximum field strength can be reduced, improving insulation reliability.

(2) Application Logic of Multiple Insulation Media

• Air Insulation: Para sa composite insulation nga air ang primary body, kinahanglan strict follow sa standards sa electrical clearance ug creepage distance sa disenyo aron balanced ang insulation performance ug equipment compactness.

• Gas Insulation: Ang gas-insulated cabinets kasagaran gamiton ang SF₆, N₂, dry compressed air, o mixed gases isip insulation media (sa low-pressure range). Bisag ang gas pressure dili taas, ang sealing design crucial—attention must be paid to the component changes of the gas due to permeation during long-term operation (such as air infiltration and insulation gas exudation). For gas-filled compartments without arc decomposition products, the moisture content must be precisely controlled: when the rated pressure ≤ 0.05MPa, it should be ≤ 2000μL/L; when > 0.05MPa, the allowable value of moisture content is calculated according to the saturated water vapor pressure at -10°C.

• Interface and Solid Insulation: When solid insulation parts are butted, elastic materials such as silicone rubber are used to eliminate air gaps and improve the interface insulation level (related to surface pressure, finish, and contact length). Using materials such as epoxy resin and silicone rubber to cast and vulcanize and package high-voltage components, and covering them with a grounding/semiconductive layer, can significantly improve the safety level, reduce the equipment volume, and simplify the layout.

3. Precise Design of Mechanical Transmission and Interlocking System

Mechanical transmission covers links such as circuit breaker operating mechanisms, disconnectors, earthing switches, and door interlocks. The design needs to be optimized from dimensions such as principle, layout, force mode (pressure/tension), span, transmission ratio, stroke angle, and mechanical efficiency: simplify the structure, reduce the number of parts, and lower the operating force, achieving “reasonable force bearing, reliable transmission, stable operation, and convenient operation and maintenance”.

The “five-prevention” interlocking is the core of ensuring operation safety—mechanical interlocking is preferred (composed of levers, connecting rods, baffles, etc. to form a lock, with clear procedures, intuitive and reliable); if the components are far apart or mechanical interlocking is difficult to implement, electrical interlocking is supplemented; intelligent cabinets can be superimposed with microcomputer software programming interlocking (used in conjunction with mechanical interlocking) to build a multi-level safety protection system.

4. Construction of a Reliable Earthing System

The earthing design needs to cover the dual requirements of “operation safety” and “fault withstand”:

• During maintenance, the earthing switch can reliably earth the main circuit according to regulations.

• The bottom frame of the shell is equipped with earthing conductors and terminals suitable for fault conditions, and the cabinets are interconnected by conductors, with a dedicated circuit between the earthing switch and the earthing conductor.

• The earthing conductors, connection circuits, and connections between cabinets must withstand the rated short-time/peak withstand current.

• The frame, cover plate, door, partition, and other components are electrically continuous to ensure the earthing connection of functional units.

• The DC voltage drop from any point of the shell metal parts to the earthing conductor through 30A is ≤ 3V, ensuring the effectiveness of earthing.

5. Technological Evolution and Development Direction

With the process of power grid transformation and cable undergrounding, multi-circuit distribution units are rapidly iterating towards “miniaturization, modularization, and automation”, which drives the innovative development of SF₆ and composite insulation technologies and high-performance components. In the future, it is necessary to focus on manufacturing process upgrades (such as precision processing and integrated packaging), optimization of cable connectors, iteration of current-limiting fuses, research and development of small operating mechanisms, and innovation of auxiliary components, so as to improve the design and manufacturing level of domestic ring main distribution equipment. Developing a new generation of ring main cabinets with “full working condition adaptation, maintenance-free, high reliability, and miniaturization” to enable distribution automation will become a key direction for industry breakthroughs.