Barranên vîndêr û Pencêkên li ser Rewşên HV û EHV
Busbars û Connectors di Installationsên Naverok û Derveyî
Ciyay Elektrik Busbar?
Busbar elektrikî ya ku ji nêranekan din bêtir û pêşkeftinê daneyê. Di navbera ku, wek birjeya heybetdar derkeve ku amperên ji nêrên daxilî û dixoyên daxilî re bi taybetmendî yek demda hewce bike. Vana bikarhêneriya busbars ên jî yên di cihazên elektrîkî de têkildanî çêna kirina rastî û parçûna elektrik.
Busbars ji bo Installationsên Derveyî
Di installationsên high - voltage (HV), extra - high - voltage (EHV) û medium - voltage (MV) derveyî de, busbars û connectors çalak bikar anîn. Cihazên ku hûn dikarin werin bikar estin divê be du jî rêng: tubular û stranded wires.
Busbars tubular hatine destnusîne ser column insulators, ku pelanîn ceramic in. Insulators-ê rolê heybetdar derkeve ku electrical isolation di busbars û structureya destnusandeya navbera biguhezînin, ku amadeyê ku cihazê elektrîkî bêtir û raşt bekar lê. Sper, stranded - wire busbars bi dead - end clamps destnusîn, ku wirên çalak bê hevî û vegerînên ku connectiona elektrîkî biguheztin.
Figures 1 û 2 mishele vizualan dide ku conceptsan di vir dike, ku şêw û installationa typîka busbars û componentsên li girtin an şêwe dike.
Busbars ji bo Installationsên Switchgear
Busbars ku di switchgear installations de bikar anîn hatine çavkirin ji copper, aluminium, û aluminium alloys wêje Al - Mg - Si (aluminium - magnesium - silicon) alloys. Materials-ê ji ber electrical conductivity, mechanical properties, û cost - effectiveness bijare, ku wekî ku hewce bike ku powera elektrîkî di systemsên switchgear de bêtir pêşkefte.
Main Characteristics of Bare Busbars
Physical Dimensions: Ji bo conductors tubular, diameter parameterê kritîk e, speri ji bo stranded - wire conductors, cross - sectional area primary importance e. Dimensions-ê直接影响电流承载能力和电气电阻。较大的直径或横截面允许传输更高的电流且损耗更低。 请注意，根据您的要求，翻译必须是库尔德语，并且不能夹杂中文或其他语言。以下是正确的库尔德语翻译：
Dimensiyonên Fizîkî: Ji bo conductors tubular, diameter parameterê kritîk e, speri ji bo stranded - wire conductors, cross - sectional area primary importance e. Dimensions-ê direkten influencê da ke current - carrying capacity û electrical resistance an. Diameter an cross - section mezinere ku currents mezin bê hesab û loss zêde pêşkeftin.
Properties Mechanical: Bare busbars hewce ye ku mechanical strength adekatey bixinan ku ji bo forces operation û re bixebit. Parameters mechanical key tensile strength (ability to resist stretching), compressive strength (resistance to squeezing), bending strength (ability to withstand bending forces), û buckling strength (resistance to deformation under compressive loads). Additionally, moments of resistance û inertia crucial for understanding how the busbar will respond to mechanical stresses, ensuring its structural integrity over time.
Rated Current: The rated current of a busbar indicates the maximum continuous current it can safely carry without excessive heating or degradation of its performance. This value is determined based on factors such as the material properties, cross - sectional area, û ambient operating conditions. Selecting a busbar with an appropriate rated current is essential to prevent overheating û potential failures in the electrical system.
It's important to note that since bare busbars are not insulated, the concept of rated voltage does not apply in the same way as it does for insulated conductors. When connecting busbars to equipment terminals, specialized connectors must be used. These connectors, as exemplified in Figure 3, ensure a secure, low - resistance electrical connection, facilitating the reliable transfer of electrical power between the busbars û other components of the switchgear system.
Busbar Connection and Insulated Busbar Systems
Busbar Connection
When it comes to making connections between busbars, the choice of connectors is crucial û depends on the materials of the busbars being joined. For copper - to - copper connections, bronze connectors are typically employed. These connectors offer excellent electrical conductivity û mechanical strength, ensuring a reliable connection. For aluminium - to - aluminium connections, aluminium alloy connectors are the ideal choice. They are specifically designed to match the properties of aluminium busbars, providing a secure û stable connection while minimizing the risk of corrosion.
In the case of copper - to - aluminium connections, bi - metallic connectors are essential. Using these connectors is necessary to prevent corrosion that can occur due to the electrolytic effect when two different metals come into contact in the presence of an electrolyte (such as moisture in the air). The electrolytic reaction between copper û aluminium can lead to the degradation of the connection over time, potentially causing electrical failures. Bi - metallic connectors are engineered to mitigate this issue, ensuring a long - lasting û reliable connection between copper û aluminium busbars.
Insulated Busbars & Trunking Systems
In indoor medium - voltage (MV) û low - voltage (LV) installations, where high currents are involved û space is at a premium, insulated busbars û trunking systems are often utilized. In these setups, busbars are enclosed within metallic enclosures, which serve dual purposes of providing mechanical protection û electrical insulation. The enclosures safeguard the busbars from physical damage, such as accidental impacts û contact with foreign objects, û also prevent electrical shocks by isolating the live conductors from the surrounding environment.
However, this enclosure comes with a trade - off. The presence of the enclosure reduces the heat dissipation of the busbars. It restricts the flow of cooling air around the busbars û decreases the radiation losses, which are important for dissipating the heat generated during current flow. As a result, the current ratings of busbars within enclosures are often significantly lower compared to those of busbars exposed to free air.
To address this issue û minimize the reduction in current - carrying capacity, ventilated enclosures can be used. These enclosures are designed with openings û vents that allow for better air circulation, facilitating more efficient heat dissipation. This helps to maintain higher current ratings while still providing the necessary mechanical protection û insulation.
Figure 4 provides an illustrative example of an enclosed busbar, showcasing the typical structure û appearance of such a system û highlighting how the enclosure is integrated with the busbars to meet the requirements of indoor electrical installations.
Isolated Busbars û Trunking Systems
Isolated Busbars
Isolated busbars are typically constructed using flat bars of copper û aluminium. The number of bars per phase can vary, depending on the magnitude of the current they are required to carry. In this setup, each individual phase or pole is encased within a separately earthed sheath. The ends of this sheath are connected by a bar rated for full short - circuit current.
The primary function of the sheath is to prevent the occurrence of inter - phase short - circuit currents. Additionally, it offers an important advantage related to magnetic fields. When current flows through the conductors, it generates strong magnetic fields. However, an equal û opposite current is induced in the enclosure or sheath, which almost completely cancels out these magnetic fields. This cancellation of magnetic fields helps to reduce electromagnetic interference û minimize the potential for unwanted effects on nearby electrical û electronic equipment.
Commonly employed insulating materials for isolated busbars include air û sulfur hexafluoride (SF6). Air is a readily available û cost - effective option, while SF6 offers superior insulating properties, making it suitable for applications where higher levels of insulation û electrical performance are required.
Trunking Systems
In low - voltage (LV) installations, one cost - effective approach to power distribution, as well as supplying power to multiple pieces of equipment û facilitating interconnections between switchboards û between a switchboard û a transformer, is the use of a trunking system. As illustrated in Figure 5, trunking systems provide a structured û efficient way to route electrical conductors, protecting them from physical damage û simplifying the installation û maintenance of electrical systems.
Trunking Systems: Features û Advantages
A trunking system consists of pre - assembled flat bar conductors (including phase û neutral conductors) enclosed within a single metallic casing. This design offers a streamlined û organized approach to electrical power distribution.
In feeder trunking systems, power extraction from the busbar trunking is achieved through the use of tap - off units. These units are connected at specific, predefined locations along the busbar trunking. They enable the safe û controlled removal of power from the system, typically via appropriate protective devices such as circuit breakers û fuses. This setup ensures that electrical power can be distributed precisely to various loads as required.
Trunking systems present several significant advantages over traditional cable - based systems:
Cost - effectiveness û Ease of Installation: Trunking systems are more economical to implement û simpler to install, especially when dealing with high - current applications. In such scenarios, achieving the necessary current ratings with single - core cables often requires using multiple cables to meet voltage drop û voltage dip specifications. This not only increases the complexity û cost of cable installation but also raises the risk of overheating between cables, which can potentially lead to short circuits. In contrast, trunking systems provide a more efficient û reliable solution for high - current power distribution.
Mechanical Strength û Installation Efficiency: They exhibit superior mechanical strength over long distances with minimal need for fixings. This characteristic significantly reduces installation times, as fewer supports û fasteners are required compared to cable runs. The robustness of trunking systems also ensures greater durability û reliability during operation.
Space - saving û Simplified Design: Trunking systems eliminate the need for multiple cable runs along with their associated supporting metalwork, simplifying the overall electrical infrastructure. This reduction in complexity not only saves space but also makes the system easier to manage û maintain.
Reduced Termination Requirements: They demand less termination space within switchboards. This is a crucial advantage, especially in switchboard designs where space is at a premium, allowing for more compact û efficient electrical panel layouts.
Eliminating the Need for Cable Jointers: Since trunking systems are pre - assembled û do not require on - site cable splicing, the need for specialized cable jointers is eliminated. This not only reduces labor costs but also minimizes the potential for errors associated with cable joining, enhancing the overall quality û reliability of the electrical installation.
Flexibility in Power Distribution: Multiple tap - off outlets provide flexibility to adapt to changes in power requirements after the initial installation, subject to the rating of the busbar trunking. This feature allows for easy reconfiguration of the electrical system to accommodate new loads û changes in load demands, making trunking systems highly adaptable to evolving electrical needs.
Ease of Repositioning û Extension: Repositioning distribution outlets is a straightforward process with trunking systems. Moreover, the system can be easily extended as the electrical requirements of a facility grow, offering a scalable solution for power distribution.
Aesthetic Appeal: In areas where the electrical system is visible, trunking systems offer an aesthetically pleasing appearance compared to bundles of cables. Their sleek û uniform design can enhance the visual appeal of a building's interior, making them a preferred choice in commercial û public spaces.
Reusability: Busbar trunking systems can be dismantled û reused in other areas, providing a cost - effective solution for facilities undergoing renovation û expansion. This reusability factor not only reduces waste but also offers significant savings in terms of material û installation costs.
Enhanced Fire Resistance: They provide better resistance to the spread of fire compared to traditional cable systems. The metallic enclosure of the trunking helps to contain fire û prevent it from spreading through the electrical system, contributing to improved fire safety in buildings.
