{"id":4434,"date":"2026-09-27T19:22:18","date_gmt":"2026-09-27T19:22:18","guid":{"rendered":"https:\/\/huyuglobal.com\/?p=4434"},"modified":"2026-09-27T19:22:20","modified_gmt":"2026-09-27T19:22:20","slug":"for-electric-power-transmission-copper-or-aluminium-wire-is-used","status":"publish","type":"post","link":"https:\/\/huyuglobal.com\/pt\/blog\/for-electric-power-transmission-copper-or-aluminium-wire-is-used\/","title":{"rendered":"Para Transmiss\u00e3o de Energia El\u00e9trica, \u00e9 Utilizado Fio de Cobre ou Alum\u00ednio?"},"content":{"rendered":"

Quando voc\u00ea olha para uma linha de energia, provavelmente ela \u00e9 feita de alum\u00ednio, embora em laborat\u00f3rio o cobre seja um condutor melhor. O fator determinante para o uso do alum\u00ednio n\u00e3o \u00e9 a eletricidade, mas o peso, a extens\u00e3o dos v\u00e3os e o pre\u00e7o. Este artigo descreve os usos de cada material, explica por que o alum\u00ednio j\u00e1 prevaleceu sobre o cobre no caso das linhas de transmiss\u00e3o a\u00e9reas, mas ainda compete com ele na transmiss\u00e3o subterr\u00e2nea e em equipamentos de manobra, e descreve o que isso implica nos pontos de termina\u00e7\u00e3o da linha.<\/p>\n

Resposta curta: A maior quantidade de transmiss\u00e3o de energia el\u00e9trica a\u00e9rea \u00e9 conduzida por fios de alum\u00ednio, pois eles representam mais de 90% dos fios importados para transmiss\u00e3o de energia. Os fios de alum\u00ednio usados para transmiss\u00e3o de energia el\u00e9trica s\u00e3o comumente conhecidos como ACSR, que se refere a fio de alum\u00ednio com n\u00facleo de a\u00e7o. Fios de cobre s\u00e3o usados em casos onde o espa\u00e7o e a confiabilidade das conex\u00f5es devem ser preferidos ao peso do fio, como em instala\u00e7\u00f5es de cabos, barramentos, motores e transformadores. O alum\u00ednio transmite apenas 61% da eletricidade que o cobre e seu custo \u00e9 cerca de 25-30% do custo do cobre, ainda assim pesa 70% menos que o cobre, o que significa que um fio de alum\u00ednio com a mesma resistividade que o cobre pesa aproximadamente metade, pois tem a mesma resist\u00eancia el\u00e9trica que o fio de cobre e \u00e9 um pouco maior em di\u00e2metro.<\/p><\/blockquote>\n

Os n\u00fameros que resolvem a discuss\u00e3o<\/h2>\n

Os dois metais se destacam na condu\u00e7\u00e3o de eletricidade, mas a diferen\u00e7a \u00e9 muito menor do que a maioria das pessoas pensa quando n\u00e3o estamos comparando fios do mesmo tamanho, mas fios de capacidade igual. O cobre \u00e9 vencedor porque \u00e9 mais volum\u00e9trico; o cobre pode transportar mais eletricidade para um fio da mesma \u00e1rea. O alum\u00ednio \u00e9 vencedor gra\u00e7as ao seu peso espec\u00edfico; \u00e9 significativamente mais leve e muito mais barato para a mesma condut\u00e2ncia.<\/p>\n\n\n\n\n\n\n\n\n\n
Propriedade a 20 \u00b0C<\/th>\nCobre estirado a frio<\/th>\nAlum\u00ednio estirado a frio<\/th>\nA\u00e7o galvanizado<\/th>\n<\/tr>\n
Resistividade (\u00d710-8<\/sup> \u03a9\u00b7m)<\/td>\n1.72<\/td>\n2.83<\/td>\naprox. 14<\/td>\n<\/tr>\n
Condutividade (1% IACS)<\/td>\n97 (cobre recozido 100)<\/td>\n61<\/td>\naprox. 12<\/td>\n<\/tr>\n
Densidade (kg\/m\u00b3)<\/td>\n8,890<\/td>\n2,703<\/td>\n7,800<\/td>\n<\/tr>\n
Resist\u00eancia \u00e0 tra\u00e7\u00e3o m\u00e1xima (MPa)<\/td>\n380-420<\/td>\n160-200<\/td>\n1,300-1,500<\/td>\n<\/tr>\n
Coeficiente de temperatura (\u00d710-3<\/sup>\/\u00b0C)<\/td>\n3.93<\/td>\n4.03<\/td>\n4.5<\/td>\n<\/tr>\n
Custo relativo do material (indicativo 2026)<\/td>\nUSD 8.800-11.000 por tonelada<\/td>\nUSD 2.400-3.200 por tonelada<\/td>\nDependente da aplica\u00e7\u00e3o<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Em termos de engenharia, as implica\u00e7\u00f5es ficam claras. Quando se trata de resist\u00eancia el\u00e9trica, o alum\u00ednio tem aproximadamente 1,6 vezes mais \u00e1rea superficial que o cobre, que \u00e9 aproximadamente 1,28 vezes mais largo que o cobre. No entanto, apesar do tamanho deste condutor, ele pesa apenas cerca de metade. Al\u00e9m disso, como os pre\u00e7os das mat\u00e9rias-primas para produ\u00e7\u00e3o de alum\u00ednio s\u00e3o significativamente mais baixos que os do cobre, um condutor de alum\u00ednio do mesmo tamanho custa aproximadamente 35-50% do seu equivalente em cobre e tamb\u00e9m \u00e9 52% mais leve por si s\u00f3.<\/p>\n

Enquanto isso, o alum\u00ednio tem uma grande desvantagem em termos mec\u00e2nicos. Sua resist\u00eancia \u00e0 tra\u00e7\u00e3o \u00e9 quase metade da do cobre. Al\u00e9m disso, apresenta desvantagens sob carga prolongada, sofrendo alongamento.<\/p>\n

\"Os<\/p>\n

Por que o alum\u00ednio venceu na linha a\u00e9rea<\/h2>\n

Ao dividir as duas responsabilidades, o problema desaparece completamente. ACSR (Aluminium Conductor Steel Reinforced) consiste em fios de alum\u00ednio na parte externa e um n\u00facleo de a\u00e7o e a\u00e7o galvanizado no interior. O n\u00facleo de a\u00e7o mant\u00e9m a tens\u00e3o enquanto o alum\u00ednio \u00e9 respons\u00e1vel por conduzir a corrente. O a\u00e7o praticamente n\u00e3o desempenha papel do ponto de vista el\u00e9trico, pois est\u00e1 localizado no n\u00facleo do condutor, com sua densidade de corrente sendo a mais baixa neste tipo de condutor. O condutor \u00e9 designado como 54\/7, o que significa que h\u00e1 54 fios de alum\u00ednio ao redor das 7 cordas do n\u00facleo de a\u00e7o.<\/p>\n

Quando o condutor \u00e9 feito leve, a constru\u00e7\u00e3o de todo o sistema de transmiss\u00e3o fica mais barata. Fios mais leves permitem v\u00e3os maiores entre os postes, o que significa menos postes, funda\u00e7\u00f5es menores e menos terreno desmatado. De acordo com v\u00e1rias estimativas da ind\u00fastria, a economia para a infraestrutura quando sistemas totalmente de cobre s\u00e3o usados pode chegar a 20-40%. Em linhas mais longas, essa vantagem supera todos os c\u00e1lculos de efici\u00eancia de condutividade.<\/p>\n

H\u00e1 outro b\u00f4nus a ser considerado. Como o design de condutores AC de resist\u00eancia igual \u00e9 cerca de 28% mais largo em di\u00e2metro, a carga el\u00e9trica \u00e9 distribu\u00edda na superf\u00edcie de forma mais uniforme e o efeito de descarga corona \u00e9 reduzido. O que parece ser um excesso de tamanho no local de constru\u00e7\u00e3o torna-se um bom b\u00f4nus no n\u00edvel de tens\u00e3o de 400 kV.<\/p>\n\n\n\n\n\n\n\n\n
Condutor<\/th>\nConstru\u00e7\u00e3o<\/th>\nFonte de resist\u00eancia<\/th>\nOnde \u00e9 utilizado<\/th>\n<\/tr>\n
AAC<\/td>\nCordas totalmente de alum\u00ednio<\/td>\nSomente alum\u00ednio<\/td>\nV\u00e3os curtos, barramento de subesta\u00e7\u00e3o, distribui\u00e7\u00e3o urbana<\/td>\n<\/tr>\n
AAAC<\/td>\nCordas de liga de alum\u00ednio-magn\u00e9sio-sil\u00edcio<\/td>\nLiga<\/td>\nAtmosferas costeiras e industriais; sem corros\u00e3o bimet\u00e1lica<\/td>\n<\/tr>\n
ACSR<\/td>\nAlum\u00ednio sobre n\u00facleo de a\u00e7o galvanizado<\/td>\nN\u00facleo de a\u00e7o<\/td>\nO padr\u00e3o para transmiss\u00e3o a\u00e9rea mundialmente<\/td>\n<\/tr>\n
ACAR<\/td>\nAlum\u00ednio sobre cordas de liga de alum\u00ednio<\/td>\nN\u00facleo de liga<\/td>\nRotas sens\u00edveis \u00e0 corros\u00e3o que necessitam de mais resist\u00eancia que AAC<\/td>\n<\/tr>\n
ACSS<\/td>\nAlum\u00ednio recozido sobre n\u00facleo de alta resist\u00eancia<\/td>\nN\u00facleo, essencialmente todo ele<\/td>\nAumento de capacidade em faixa de servid\u00e3o existente; alta temperatura de opera\u00e7\u00e3o<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Where copper still wins, and why<\/h2>\n

The underground cable is the last bastion of copper in the cable industry, and the reason for that is the issue of space. A trench, duct, or cable tray has a predetermined space, and any extra square millimeter of the conductor needs to be justified by digging, ducting, and pulling efforts. Wherever there is a need for a large cross-section, copper conductivity wins the competition. Underwater use creates one more rationale for copper use: strong construction for long supportless runs and at the entry points where cable is pulled.<\/p>\n

In electrical devices the picture is even clearer. Busbars, motor and transformer windings, contactor coils, control wires are all made of copper, since the housing has a fixed size, and connection quality manifests itself more than price of metal. 3,200 A of electrical busbar made out of copper should have about 1.6 times smaller section made of aluminum which normally does not fit. DC traction (metro third rail and overhead systems, arc furnaces, electrolytic plants) remains with copper for the same purpose.<\/p>\n

Then there is the conversion argument: any current system constructed from copper cannot be transitioned into aluminum without changing all the assumptions regarding ampacity, fault ratings and protection settings at the same time.<\/p>\n

The failure modes that gave aluminium a bad name<\/h2>\n

Aluminium has gained a bad reputation that it has largely earned \u2014 but it is not the material’s fault. During a time of unprecedented copper costs, it was then assumed that the same technologies, devices, and torque values being used on copper would also work when using aluminium in homes in North America. Three properties then played into the situation.<\/p>\n

First, aluminium reacts with oxygen and forms an oxide coating, which is an insulating material that has a melting point of around 2,072 \u00b0C; thus, it is good for corrosion-resistance and not good for screw terminals. Secondly, aluminium expands significantly more than copper during thermal cycles; therefore, the connection made is going to be loose after a great number of thermal cycling. Thirdly, since aluminium is anodic to copper, the presence of moisture causes galvanic corrosion of the contact whenever there is a direct contact of the two metals.<\/p>\n

All these problems lead to one classic failure: a receptacle getting warm enough to develop arcs. The solutions for making modern aluminium wiring safe are oxide inhibiting compound applied directly at connections, CO\/ALR-rated devices used especially for aluminium conductors, bimetallic transition connections between copper and aluminium, as well as torque values calculated and considered in respect of expanding properties of aluminium.<\/p>\n

For anyone working on existing aluminium branch circuits, the diagnostic is heat rather than appearance. A termination that has begun to fail will usually show discoloured insulation, a scorched device or nuisance tripping long before it fails outright, and the same fingerprint \u2014 warmth under light load, then trips that make no sense \u2014 is how you catch a breaker that has gone bad<\/a> at the other end of the circuit.<\/p>\n

Matching the conductor to the voltage class<\/h2>\n

The way power is transmitted changes as the transmission voltage changes, and the change is caused by geometry and not economics.Above roughly 220 kV, lines carry more than one conductor per phase, and the same logic that governs the difference between high voltage and low voltage<\/a> design decides how many. A 400 kV line commonly runs two or four sub-conductors per phase in a bundle rather than one very large conductor.<\/p>\n

The change in power transmission has to do with inductance and corona effects. Inductance of a power line is determined only by the physical radius of the wire, and the increase of the radius of a single wire does not have much influence on inductance. To make it effective, wires are bundled into a number of smaller wires, therefore, the effective radius increases with the number of wires, while maintaining the electric field at the surface low enough to avoid corona. Hence, the aluminum content in the wires grows with voltage, and the design of the wires is done beforehand, thus it does not depend on the manufacturer.<\/p>\n\n\n\n\n\n\n\n
ACSR code name<\/th>\nStranding Al \/ steel<\/th>\nOverall diameter<\/th>\nDC resistance at 20 \u00b0C<\/th>\nUso t\u00edpico<\/th>\n<\/tr>\n
Dog<\/td>\n6\/4.72 + 7\/1.57<\/td>\n14.15 mm<\/td>\n0.2745 \u03a9\/km<\/td>\n33-66 kV lines<\/td>\n<\/tr>\n
Panther<\/td>\n30\/3.00 + 7\/3.00<\/td>\n21.00 mm<\/td>\n0.1390 \u03a9\/km<\/td>\n132 kV lines<\/td>\n<\/tr>\n
Zebra<\/td>\n54\/3.18 + 7\/3.18<\/td>\n28.62 mm<\/td>\n0.0688 \u03a9\/km<\/td>\n220 kV and 400 kV, bundled<\/td>\n<\/tr>\n
Moose<\/td>\n54\/3.53 + 7\/3.53<\/td>\n31.77 mm<\/td>\n0.0561 \u03a9\/km<\/td>\n400 kV, twin or quad bundle<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

These names are derived from national conductor catalogs, while the figures that follow \u2014 including diameter, stranding, resistance, and geometric mean radius \u2014 are key considerations in designing a line. The first aspect concerning the substance of the conductor is resolved far in advance of reviewing the conductor table.<\/p>\n

\"Matching<\/p>\n

Ampacity, temperature and terminal ratings<\/h2>\n

The lower conductivity of aluminium extends to the ampacity tables as well. With the same conductor size, aluminium is able to conduct around 78-80% of the ampacity of copper at the same temperature rating for insulation. For example, a 1\/0 conductor rated at 75 \u00b0C presents an ampacity of 150 A in copper and an ampacity of 120 A in aluminium. In order to achieve the same ampacity level, it is necessary to use a larger conductor \u2014 the general rule is to use a conductor that is two AWG sizes larger than in copper.In the end, this brings the issue of the space \u2014the aluminium conductor that conducts the required current requires different raceway sizes, different lugs and more space at the panel.<\/p>\n

Two details in the code create most cases of errors in the field. The first one is the fact that ampacity depends on the temperature ratings of wiring and terminations. A 90 \u00b0C insulated conductor connected to a 75 \u00b0C rated terminal can only be used at the lower figure unless the assembly is listed otherwise, and that listing is exactly what a UL 489 molded case circuit breaker<\/a> declares in its terminal temperature rating rather than in its marketing literature. The second detail is that aluminium connections must be made using connectors that are listed as suitable for aluminium wiring, using the aforementioned torque and the oxide inhibitor according to the specifications of the connector manufacturer.<\/p>\n

What this means for switchgear and terminations<\/h2>\n

At this stage, the decision made by the conductor is no longer a decision regarding the wire, but one concerning the switchgear. The use of aluminium feeders requires that every piece of equipment connected to the wires is rated for both aluminium and copper; the termination equipment has to be bimetallic involving an aluminium and copper connection wherever aluminium is used with copper.<\/p>\n

HUYU’s manufacturing line makes components such as MCBs, MCCBs, air circuit breakers, contactors, relays, current transformers, surge protection devices, automatic transfer switches and PV combiner boxes. We do not produce wire, thus we do not view it to be up to us to make the choice between aluminium and copper.What we do is supply equipment whose terminals are rated for both, with the torque and conductor-range data published \u2014 a DIN-rail O que diferencia este sofisticado<\/a> is only a 63 A device to the extent its terminals accept the conductor you bring to it.<\/p>\n

As we have learnt from our experience with failures in the field, it is important to remember that whenever a feeder changes material during a run, the junction of that change must be at a designated terminal or at a bimetallic connector \u2014 never half-way along a run with a split bolt and a piece of tape.<\/p>\n

How to decide on a real project<\/h2>\n\n\n\n\n\n\n\n\n\n
Aplica\u00e7\u00e3o<\/th>\nMaterial<\/th>\nMotivo<\/th>\n<\/tr>\n
Overhead transmission and distribution<\/td>\nAluminium (ACSR \/ AAAC)<\/td>\nWeight, span length, tower cost, diameter and corona<\/td>\n<\/tr>\n
Underground and submarine cable<\/td>\nCopper, sometimes aluminium for large LV<\/td>\nCross-section is expensive; robustness at landing points<\/td>\n<\/tr>\n
Switchgear busbars and control wiring<\/td>\nCobre<\/td>\nFixed enclosure volume; connection reliability<\/td>\n<\/tr>\n
Motor and transformer windings<\/td>\nCopper; aluminium in cost-driven distribution units<\/td>\nWinding space, losses, heat dissipation<\/td>\n<\/tr>\n
Building feeders, larger circuits<\/td>\nAluminium for size and cost; copper for tight routes<\/td>\nTrade-off between metal cost and raceway space<\/td>\n<\/tr>\n
Existing installations<\/td>\nMatch what is already there<\/td>\nAvoid re-rating studies and mixed-metal terminations<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

System-level decisions often push the answer one step further. On a large industrial site, the conductor material interacts with the distribution architecture \u2014 how many transformers, how long the MV runs, how much MV switchgear \u2014 which is why enterprise-scale distribution systems<\/a> are designed as a whole rather than conductor by conductor, and why optimising the architecture usually saves more than the metal swap does.<\/p>\n

FAQ<\/h2>\n

Is aluminium or copper better for power transmission?<\/h3>\n

Aluminium is preferred for overhead lines by an enormous factor, with more than 90% of the global network employed in its use. Copper is better suited for underground lines, equipment, or situations where the cross-section is predetermined. They both have their strengths; the question then is which constraint applies to the situation in question.<\/p>\n

Why is aluminium used instead of copper in overhead lines?<\/h3>\n

This is because an aluminium conductor with the same resistance weighs only approximately half as much and costs about 35-50% of the price of the copper equivalent. The fact that the weight is half makes the spans longer and more towers and smaller foundations are needed to properly support the structure.<\/p>\n

Can copper and aluminium wires be connected directly?<\/h3>\n

Avoid using it in any damp or exterior area. Aluminium is electropositive to copper, which can cause galvanic action in the presence of moisture within the connection. Therefore, make sure to use special bimetal connectors designed specifically for the two metals.<\/p>\n

Does aluminium wire carry less current than copper of the same size?<\/h3>\n

Indeed, typically the Copper rating is around 78 to 80 percent for the same insulation temperature of the insulation. If you want the same amount of current and voltage, you’ll use about two AWG sizes up which would require bigger conductors and therefore bigger sizes of both raceways and lugs as well.<\/p>\n

What is ACSR and why is the steel core there?<\/h3>\n

The Aluminium Conductor Steel Reinforced (ACSR) is formed by placing a steel wire core at the centre of several layers of aluminum wires. The role of steel is to take the tensile stress that the hard drawn aluminum cannot manage on long spans, while the aluminum is responsible for carrying electrical current. Since steel is located in the central part of the conductor where the place for the electrical current is minimum, almost no electrical loss occurs.<\/p>\n

Is aluminium wiring in a house dangerous?<\/h3>\n

Not per se, but it does require proper device installation. The mistakes that happened in the 1960s and 1970s can be attributed to the use of aluminum wire connectors with devices that were not rated for such conductors, but were utilized without the appropriate installation or proper torque. Nowadays, with the use of the oxide-inhibiting compound, the devices rated for CO\/ALR rating, as well as bimetallic gadgets the process works correctly and efficiently under the condition that those requirements are fulfilled.<\/p>\n

Refer\u00eancias<\/h2>\n