Name: overhead power line materials and safety
Uploaded: 2024-11-21T14:54:23.000Z
Duration: 1 min 23 s
Channel: JoVE

O alumínio, sendo abundante e econômico, substituiu amplamente o cobre nas linhas de transmissão aéreas. O popular condutor de alumínio reforçado com aço consiste em camadas de fios de alumínio em torno de um núcleo de aço.
Outros tipos incluem condutores de aço totalmente em alumínio, totalmente em liga de alumínio, reforçados com liga de condutor de alumínio e revestidos de alumínio. Condutores de alumínio com suporte de aço e condutores de alumínio ZT do tipo gap podem operar acima de 150ºC. O projeto elétrico para linhas de transmissão considera o tipo de condutor, tamanho, número de feixes por fase, capacidade térmica, controle de gradiente de tensão, discos isoladores, folga e isolamento da linha. Os fios blindados interceptam raios e reduzem a resistência da base da torre.
As linhas de transmissão operando acima de 69 kV usam isoladores do tipo suspensão, normalmente feitos de porcelana, vidro temperado ou discos de polímero.
As estruturas que suportam essas linhas variam de torres de aço treliçado para altas tensões a estruturas de madeira para tensões mais baixas.
O projeto mecânico garante estabilidade, enquanto as considerações ambientais levam em conta o uso da terra e o impacto visual.

considerações sobre o projeto de linhas de transmissão

Transmission Line Design Considerations

O alumínio se tornou o material preferido para linhas de transmissão aéreas, superando o cobre devido à sua abundância e custo-benefício. O tipo mais prevalente é o condutor de alumínio reforçado com aço (ACSR), que combina fios de alumínio em torno de um núcleo de aço. Outras variantes incluem condutores totalmente de alumínio (AAC), condutores totalmente de liga de alumínio (AAAC), condutores de alumínio reforçados com liga (ACAR) e condutores de aço revestidos de alumínio. Projetos avançados, como condutores de alumínio com suporte de aço e condutores de alumínio ZT do tipo gap, podem operar em temperaturas superiores a 150 graus Celsius.


 O projeto elétrico de linhas de transmissão envolve vários fatores críticos. Isso inclui o tipo e o tamanho do condutor, o número de feixes por fase e a capacidade térmica dos condutores. O controle do gradiente de tensão é essencial para minimizar as perdas de energia. Discos isolantes, que são colocados entre os condutores e as estruturas de suporte, são usados ​​para garantir o isolamento adequado. A folga adequada e o isolamento da linha são vitais para a segurança e a eficiência. Fios de blindagem são colocados estrategicamente, interceptando raios para reduzir a resistência da base da torre e proteger as linhas de transmissão.


 Linhas de transmissão operando acima de 69 quilovolts (kV) normalmente empregam isoladores do tipo suspensão, que consistem em cordas de porcelana, vidro temperado ou discos de polímero. As estruturas de suporte variam com base nos níveis de tensão, com torres de aço treliçadas autossustentáveis ​​usadas para linhas de alta tensão e armações de madeira para aplicações de baixa tensão. Fios de blindagem, geralmente feitos de aço de alta resistência ou Alumoweld, protegem contra raios e são devidamente aterrados para garantir a segurança.


 O projeto mecânico garante a resistência e a durabilidade dos condutores, cordas isolantes e estruturas de suporte. Considerações ambientais também são cruciais, abrangendo o uso do solo e o impacto visual. O objetivo é chegar a um projeto de linha ideal que atenda a todos os critérios técnicos, minimizando os custos, considerando as despesas de instalação e as perdas operacionais.

Considerações sobre o projeto de linhas de transmissão

O alumínio, sendo abundante e econômico, substituiu amplamente o cobre nas linhas de transmissão aéreas. O popular condutor de alumínio reforçado com aço ...

Education

JoVE Core

Electrical Engineering

Engenharia Elétrica

Unit 1

Unidade 1

Transmission Line Parameters

Parâmetros da Linha de Transmissão

KEY TERMS AND CONCEPTS

TERMOS E CONCEITOS-CHAVE

overhead power line materials and safety

Overhead transmission lines rely on the right materials, insulation, and support hardware to move electricity safely and efficiently. Aluminum is now the preferred conductor material because it is abundant and cost-effective. Copper was used more often in the past, but aluminum has become the common choice for modern lines.

The most widely used conductor is aluminum conductor, steel-reinforced, or ACSR. It uses aluminum strands around a steel core for added strength. Other conductor types include all-aluminum conductors, all-aluminum alloy conductors, aluminum conductor alloy-reinforced, and aluminum-clad steel conductors. Some advanced designs, such as aluminum conductors with steel support and gap-type ZT-aluminum conductors, can operate above 150 degrees Celsius.

Transmission line design also depends on electrical limits and line safety. Engineers choose the conductor type and size, the number of bundles per phase, and the thermal capacity of the conductors. Voltage gradient control helps reduce energy loss. Insulator discs sit between the conductors and the support structures. Proper clearance and line insulation are also important for safe and efficient operation.

Shield wires add another layer of protection. They are placed to intercept lightning strikes and reduce tower footing resistance. This helps protect the transmission line from damage. Lines above 69 kilovolts usually use suspension-type insulators made from porcelain, toughened glass, or polymer discs.

The support structure changes with voltage level. High-voltage lines often use self-supporting lattice steel towers, while lower-voltage lines may use wooden frames. Shield wires are usually made from high-strength steel or Alumoweld, and they are grounded for safety. Mechanical design must keep the conductors, insulator strings, and support structures strong and durable. Environmental factors also matter, including land use and visual impact. The best line design meets technical needs while keeping installation costs and operating losses as low as possible.

Overhead Power Line Materials and Safety

transmission line design considerations

Overhead transmission lines rely on the right materials, insulation, and support hardware to move electricity safely and efficiently. Aluminum is now the preferred conductor material because it is abundant and cost-effective. Copper was used more often in the past, but aluminum has become the common choice for modern lines. The most widely used conductor is aluminum conductor, steel-reinforced, or ACSR. It uses aluminum strands around a steel core for added strength. Other conductor types...

resistance and conductance

How Transmission Lines Lose Energy

Transmission lines lose energy through resistance and conductance. DC resistance depends on a conductor’s resistivity, length, and cross-sectional area. Resistivity is a material property, and annealed copper is the international standard used for measurement. Material choice and conductor shape both matter. Hard-drawn aluminum at 20 degrees Celsius has a resistivity equal to 61% of the standard conductivity of annealed copper. Stranded conductors also gain a little extra resistance because...

inductance: solid cylindrical conductor

Magnetic Flux Linkage in Solid Conductors

Magnetic flux linkage in a solid cylindrical conductor is found by combining the field inside the wire with the field around it. The method uses a 1-meter section of a non-magnetic conductor with radius r. It also assumes the current is spread uniformly and ignores end effects. Inside the conductor, Ampere's law is used to find the magnetic field intensity H. The field is concentric and constant within the conductor. From H, the magnetic flux density B inside the wire is calculated. The...

inductance: single-phase and three-phase line

inductance-single-phase-and-three-phase-line

Transmission Line Inductance in Power Cables

Transmission line inductance helps explain how current-carrying conductors behave in power systems. It is especially important when studying single-phase two-wire lines and three-phase three-wire lines with equal phase spacing. These line types are common models for efficient transmission design and operation. A single-phase line uses two solid cylindrical conductors, labeled x and y. Each conductor carries a phasor current, ix and iy, and the sum of these currents is zero. The total flux...

series impedances: three-phase line

Three-Phase Line Impedance Matrix

Three-phase line impedance matrix calculations describe how resistance and inductive reactance behave in an overhead power line. The model includes three phase conductors and multiple neutral conductors that are grounded at regular intervals. It also accounts for unbalanced phase currents, which can send return current through the neutral wires and the earth along the lowest-impedance path. Kirchhoff’s laws are used to build an integro-differential equation for the conductor network. To make...

capacitance: single-phase and three-phase line

capacitance-single-phase-and-three-phase-line

Transmission Line Capacitance in Power Systems

Transmission line capacitance affects how power lines store charge and behave in electrical power systems. It is an important part of line modeling because it helps describe efficient operation. For a single-phase line, the key idea is the charge on the conductors and the voltage between them. A single-phase transmission line uses two wires with equal spacing. One conductor carries a uniform positive charge, and the other carries an equal negative charge. From the voltage between the...

shunt admittances

Image Method for Line Capacitance

Image conductors help model line capacitance in transmission lines above Earth. A uniformly charged conductor induces an equal and opposite charge on the ground. This creates electric field lines between the conductor and the Earth. The method of images replaces the Earth with a matching conductor placed symmetrically below the line. The image conductor has the same radius and the same charge magnitude as the original conductor. That setup keeps the electric field and voltage above the Earth...

key terms and concepts

Learn how aluminum conductors, insulators, shield wires, and tower designs keep overhead transmission lines efficient, durable, and safe.

Overhead Power Line Materials and Safety | JoVE K12

JoVE Core Electrical Engineering offers easy-to-understand animated videos that cover fundamental concepts of electric circuits along with circuit analysis techniques. It incorporates first-order and second-order circuits using operational amplifiers and circuit transformation concepts. The inclusion of practical design examples and real-world applications through scientist-in-action videos adds significant educational value, making complex concepts accessible.

electrical engineering

Overhead Power Line Materials and Safety

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