{"id":10651,"date":"2026-08-29T23:43:23","date_gmt":"2026-08-29T15:43:23","guid":{"rendered":"https:\/\/q8bbzjnpm5.wpdns.site\/?p=10651"},"modified":"2026-08-29T23:43:23","modified_gmt":"2026-08-29T15:43:23","slug":"how-to-choose-transformers-for-moist-tunnels-focus-on-these-3-points","status":"publish","type":"post","link":"https:\/\/subian-electric.com\/pt\/news\/how-to-choose-transformers-for-moist-tunnels-focus-on-these-3-points\/","title":{"rendered":"Como Escolher Transformadores para T\u00faneis \u00damidos? Foque Nestes 3 Pontos"},"content":{"rendered":"<p>Se voc\u00ea visitar a sala de comuta\u00e7\u00e3o entre as duas extremidades de um t\u00fanel urbano de rodovia no meio da temporada de ver\u00e3o e ver sua condi\u00e7\u00e3o, voc\u00ea teria a resposta. O transformador de 800kVA, que \u00e9 a principal fonte de energia do sistema de ventila\u00e7\u00e3o e ilumina\u00e7\u00e3o do t\u00fanel, est\u00e1 localizado dentro de uma sala com n\u00edvel de umidade acima de 85% por meses. Todas as noites, a condensa\u00e7\u00e3o se forma na superf\u00edcie do tanque. As paredes da sala mostram manchas causadas por dep\u00f3sitos de sal devido aos materiais de descongelamento descarregados da pista. O hist\u00f3rico de manuten\u00e7\u00e3o relata tr\u00eas casos de desconex\u00e3o dos rel\u00e9s este ano devido a problemas que causam a forma\u00e7\u00e3o de curtos-circuitos nas barras coletoras de baixa tens\u00e3o devido \u00e0 umidade. O teste do \u00f3leo mostra que cont\u00e9m 42 ppm de \u00e1gua, o que est\u00e1 acima da taxa permitida de 30 ppm e causa degrada\u00e7\u00e3o da isola\u00e7\u00e3o feita de papel.<\/p>\n<p>T\u00faneis s\u00e3o alguns dos lugares mais dif\u00edceis para usar transformadores devido \u00e0 umidade que possuem. Este artigo apresenta 3 quest\u00f5es importantes que voc\u00ea deve ter em mente ao selecionar transformadores para t\u00faneis: prote\u00e7\u00e3o de isolamento e inv\u00f3lucro, sele\u00e7\u00e3o de materiais e prote\u00e7\u00e3o contra corros\u00e3o, e controle de ventila\u00e7\u00e3o e condensa\u00e7\u00e3o.<\/p>\n<blockquote><p>A resposta breve \u00e9 apresentada aqui: Ao selecionar um transformador para t\u00faneis \u00famidos, tr\u00eas coisas devem ser consideradas: (1) Prote\u00e7\u00e3o por inv\u00f3lucro e isolamento \u2013 para os tipos secos de transformadores, inv\u00f3lucros classificados como IP54 e IP55 devem ser especificados. No caso de transformadores imersos em \u00f3leo, tanques selados feitos de materiais resistentes \u00e0 corros\u00e3o devem ser especificados; (2) Materiais resistentes \u00e0 corros\u00e3o \u2013 inv\u00f3lucros feitos de a\u00e7o inoxid\u00e1vel ou materiais revestidos a p\u00f3 de alta resist\u00eancia, acabamentos classificados para a classe de corrosividade C3\/C4 de acordo com a ISO 12944, isolamentos tropicalizados com altos n\u00edveis de umidade; (3) Ventila\u00e7\u00e3o e preven\u00e7\u00e3o de condensa\u00e7\u00e3o \u2013 troca controlada de ar, aquecedores anti-condensa\u00e7\u00e3o; controladores de umidade.<\/p><\/blockquote>\n<p style=\"text-align: center;\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-10653\" src=\"https:\/\/subian-electric.com\/wp-content\/uploads\/2026\/08\/How-To-Choose-Transformers-For-Moist-Tunnels-Focus-On-These-3-Points.webp\" alt=\"How To Choose Transformers For Moist Tunnels Focus On These 3 Points\" width=\"1448\" height=\"1086\" \/><\/p>\n<hr \/>\n<h2 id=\"why\">Por que T\u00faneis \u00damidos Destruem Transformadores<\/h2>\n<p>A falha de um transformador em ambientes \u00famidos n\u00e3o \u00e9 geralmente um acidente el\u00e9trico instant\u00e2neo \u2014 em vez disso, \u00e9 um processo qu\u00edmico e f\u00edsico gradual. Aqui est\u00e3o as principais causas:<\/p>\n<ul>\n<li>Umidade no isolamento: Em transformadores imersos em \u00f3leo, a umidade entra atrav\u00e9s de respiradouros, juntas e condensa\u00e7\u00e3o. N\u00edveis de umidade acima de 30 ppm no \u00f3leo do transformador aceleram o envelhecimento do isolamento de papel, reduzindo a vida pela metade a cada umidade duas vezes maior que o normal. Em 50\u201360 ppm, a forma\u00e7\u00e3o de bolhas pode ocorrer durante sobrecarga e levar a uma falha diel\u00e9trica.<\/li>\n<li>Rastreamento de superf\u00edcie e creepage: Em enrolamentos e buchas de tipo seco, a umidade junto com poeira ou sal cria canais condutivos ao longo da superf\u00edcie que levam a descargas parciais e flashover.<\/li>\n<li>Corros\u00e3o de tanque, acess\u00f3rios e conex\u00f5es: O condensado contendo sal ataca tanques, aletas de radiadores, acess\u00f3rios de cabos e conex\u00f5es aparafusadas, aumentando a resist\u00eancia de contato e, finalmente, causando juntas quentes.<\/li>\n<li>Condensa\u00e7\u00e3o dos compartimentos de controle e baixa tens\u00e3o: Flutua\u00e7\u00f5es de temperatura fazem com que a \u00e1gua se condense sobre os barramentos e m\u00f3dulos eletr\u00f4nicos e apenas um incidente de condensa\u00e7\u00e3o pode levar a um arco el\u00e9trico fase a fase.<\/li>\n<\/ul>\n<p>E as estat\u00edsticas confirmam a f\u00edsica: transformadores em locais costeiros e de t\u00faneis apresentam uma taxa de falha 2\u20133 vezes maior em compara\u00e7\u00e3o com as unidades em \u00e1reas secas do interior, sendo o envelhecimento do isolamento induzido pela umidade a principal causa de falha encontrada em investiga\u00e7\u00f5es forenses. A solu\u00e7\u00e3o n\u00e3o \u00e9 manuten\u00e7\u00e3o \u2014 \u00e9 a especifica\u00e7\u00e3o correta durante a aquisi\u00e7\u00e3o.<\/p>\n<h2 id=\"point1\">Ponto 1: Prote\u00e7\u00e3o de Inv\u00f3lucro e Isolamento<\/h2>\n<p>A quest\u00e3o principal \u00e9 como prevenir que a umidade impacte o isolamento. Em termos de linguagem de especifica\u00e7\u00e3o, \u00e9 importante ser preciso:<\/p>\n<table>\n<thead>\n<tr>\n<th>Elemento<\/th>\n<th>Norma \/ Requisito<\/th>\n<th>Especifica\u00e7\u00e3o de Grau de T\u00fanel<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Inv\u00f3lucro de tipo seco<\/td>\n<td>Classifica\u00e7\u00e3o IP da IEC 60529<\/td>\n<td>IP54 m\u00ednimo; IP55 onde a pulveriza\u00e7\u00e3o de \u00e1gua \u00e9 poss\u00edvel<\/td>\n<\/tr>\n<tr>\n<td>Tanque imerso em \u00f3leo<\/td>\n<td>IEC 60529 + design selado<\/td>\n<td>Tanque selado com sistema de preserva\u00e7\u00e3o de \u00f3leo (cobertura de nitrog\u00eanio ou tipo de adsor\u00e7\u00e3o de g\u00e1s)<\/td>\n<\/tr>\n<tr>\n<td>Buchas e termina\u00e7\u00f5es<\/td>\n<td>IEC 60529 \/ creepage conforme IEC 60076<\/td>\n<td>Dist\u00e2ncias de creepage estendidas, abrigos de silicone ou ep\u00f3xi, caixas de cabos IP54<\/td>\n<\/tr>\n<tr>\n<td>Compartimentos de controle \/ LV<\/td>\n<td>IEC 60529<\/td>\n<td>Compartimentos IP55 com portas vedadas e filtros de respiradores<\/td>\n<\/tr>\n<tr>\n<td>Sistema de isolamento<\/td>\n<td>IEC 60076-11 (seco), IEC 60076-1 (\u00f3leo)<\/td>\n<td>Isolamento tropicalizado, limites de teor de umidade especificados na ficha t\u00e9cnica<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>O erro usual \u00e9 especificar inv\u00f3lucros IP23 ou IP31 \u2014 enquanto podem ser adequados para uso industrial em ambientes internos, n\u00e3o funcionar\u00e3o em casos expostos a condi\u00e7\u00f5es constantes de umidade de um t\u00fanel. Cada porcentagem de melhoria de IP geralmente custa cerca de 400\u20131.500 d\u00f3lares por unidade, e ainda \u00e9 precisamente a distin\u00e7\u00e3o entre IP31 e IP55 que determina se um transformador de t\u00fanel durar\u00e1 cinco anos.<\/p>\n<h2 id=\"point2\">Ponto 2: Resist\u00eancia \u00e0 Corros\u00e3o e Materiais<\/h2>\n<p>O segundo ponto importante na tomada de decis\u00e3o \u00e9 a escolha do material. Em um ambiente \u00famido de t\u00fanel, o acabamento da superf\u00edcie e a qualidade do metal s\u00e3o igualmente essenciais quanto ao design dos sistemas el\u00e9tricos. A norma aplic\u00e1vel \u00e9 a ISO 12944 (tintas e revestimentos para constru\u00e7\u00f5es de a\u00e7o), que divide a corrosividade atmosf\u00e9rica em categorias de C1 (interiores ventilados) a C5-X (muito forte). Os t\u00faneis com respingos de carros s\u00e3o geralmente reconhecidos como C3 ou C4, enquanto t\u00faneis ricos em sal podem alcan\u00e7ar a categoria C5-I.<\/p>\n<table>\n<thead>\n<tr>\n<th>Componente<\/th>\n<th>Especifica\u00e7\u00e3o Padr\u00e3o<\/th>\n<th>Especifica\u00e7\u00e3o de Grau de T\u00fanel<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Revestimento de tanque e inv\u00f3lucro<\/td>\n<td>ISO 12944 C2\/C3, camada \u00fanica<\/td>\n<td>Sistema de revestimento C4 ou C5, espessura m\u00ednima de filme seco de 120\u2013240 \u00b5m<\/td>\n<\/tr>\n<tr>\n<td>Material da carca\u00e7a do inv\u00f3lucro<\/td>\n<td>A\u00e7o laminado a frio, pintura<\/td>\n<td>A\u00e7o inoxid\u00e1vel (304\/316) ou galvanizado a quente + revestimento em p\u00f3 pesado<\/td>\n<\/tr>\n<tr>\n<td>Fixadores e acess\u00f3rios<\/td>\n<td>A\u00e7o zincado<\/td>\n<td>Fixadores de a\u00e7o inoxid\u00e1vel, conectores de cabo de lat\u00e3o ou inoxid\u00e1vel<\/td>\n<\/tr>\n<tr>\n<td>Radiadores \/ aletas de resfriamento<\/td>\n<td>A\u00e7o carbono padr\u00e3o<\/td>\n<td>Aletas revestidas ou margem de resfriamento aumentada para compensar a perda de revestimento<\/td>\n<\/tr>\n<tr>\n<td>Respiradores de gel de s\u00edlica<\/td>\n<td>Padr\u00e3o<\/td>\n<td>Reagent-grade silica gel with color indicator, larger volume<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>The cost impact exists but is limited; moving from C2 to C4 coating typically results in added costs of anywhere from $600 to $2,500 per unit. Adding a stainless steel enclosure shell to a dry type unit that has a rating of 1,000 kVA leads to costs from $3,000 to $8,000. When dealing with critical tunnel infrastructure that cannot be removed from service for repainting, this cost is the cheapest form of insurance available.<\/p>\n<p style=\"text-align: center;\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-10654\" src=\"https:\/\/subian-electric.com\/wp-content\/uploads\/2026\/08\/Point-1-3.webp\" alt=\"Point 1-3\" width=\"1448\" height=\"1086\" \/><\/p>\n<h2 id=\"point3\">Point 3: Ventilation and Condensation Control<\/h2>\n<p>The third criterion is environmental control in the transformer room or enclose. When the surrounding air condenses, no matter how effective is the IP55 enclosure, it will not save the transformer from damage. Possible solutions to this problem listed in order of their effectiveness are the following:<\/p>\n<ul>\n<li>Anti-condensation heaters: of 150\u2013300 W per compartment and regulated by thermostat, anti-condensation heaters enable surfaces to remain 3\u20135 \u00b0C above dew point. Price is between $200 and $600 per compartment.<\/li>\n<li>Controlled ventilation: in a humid tunnel, even natural ventilation system is not helpful; a fan system that is activated only when outdoor air is drier is required. It costs from $1,500 to $5,000.<\/li>\n<li>Dehumidification: in critical rooms, a small dehumidifier ensures that the level of humidity is less than 60%. In this case, it costs from $1,000 to $3,500.<\/li>\n<li>Heated breathers and sealed oil systems: this solution excludes the risk of a moisture ingress for oil-immersed equipment. Price is covered by the above-mention option.<\/li>\n<\/ul>\n<p>The engineering task is simple and straightforward: one should keep the level of humidity in the zone of equipment above 60% and surface temperatures above dew point. These measures should be included into the transformer specifications package and should not be treated as additional civil works, as the transformer manufacturer should be responsible for moisture prevention.<\/p>\n<h2 id=\"types\">Transformer Types for Tunnel Duty<\/h2>\n<p>Both major transformer families can be made tunnel-worthy, but the choice affects cost, footprint, and fire safety:<\/p>\n<table>\n<thead>\n<tr>\n<th>Tipo<\/th>\n<th>Strengths in Tunnels<\/th>\n<th>Weaknesses<\/th>\n<th>Typical Price, 1,000 kVA (USD)<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Transformador seco (resina fundida)<\/td>\n<td>No oil leak risk, fire-safe, low maintenance, good moisture performance with proper enclosure<\/td>\n<td>Higher cost, sensitive to sustained high humidity without enclosure<\/td>\n<td>$18,000\u2013$32,000<\/td>\n<\/tr>\n<tr>\n<td>Sealed oil-immersed<\/td>\n<td>Lower cost, proven, sealed tank resists ingress<\/td>\n<td>Oil containment and fire considerations; tank corrosion risk if coating fails<\/td>\n<td>$12.000\u2013$22.000<\/td>\n<\/tr>\n<tr>\n<td>Stainless-steel dry-type<\/td>\n<td>Maximum corrosion resistance, best for salt tunnels<\/td>\n<td>Highest cost<\/td>\n<td>$25,000\u2013$40,000<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>In the case of railway tunnel and highway tunnel, the dry transformer is usually the best option in fireproof rooms because in case of a fire in tunnel the transformer can pose a danger and there are not many possibilities for people to escape. In the case of utility duct and underground tunnels where fire risk is managed differently, the best choice will be oil-filled transformers.<\/p>\n<h2 id=\"compare\">Dry-Type vs. Oil-Immersed for Tunnels<\/h2>\n<p>The decision between the two families in a moist tunnel comes down to five factors, summarized below:<\/p>\n<table>\n<thead>\n<tr>\n<th>Fator<\/th>\n<th>Dry-Type (Cast Resin)<\/th>\n<th>Sealed Oil-Immersed<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Moisture handling<\/td>\n<td>Good with IP54+ enclosure; insulation moisture recoverable by drying<\/td>\n<td>Sealed tank resists ingress; oil moisture must be monitored<\/td>\n<\/tr>\n<tr>\n<td>Fire safety<\/td>\n<td>Self-extinguishing, minimal smoke<\/td>\n<td>Oil fire risk; needs fire-rated room and containment<\/td>\n<\/tr>\n<tr>\n<td>Manuten\u00e7\u00e3o<\/td>\n<td>Low; periodic cleaning and thermography<\/td>\n<td>Higher; oil sampling, DGA, breather service<\/td>\n<\/tr>\n<tr>\n<td>Cost (1,000 kVA)<\/td>\n<td>$18,000\u2013$32,000<\/td>\n<td>$12.000\u2013$22.000<\/td>\n<\/tr>\n<tr>\n<td>Typical tunnel use<\/td>\n<td>Road\/rail station and equipment rooms<\/td>\n<td>Utility ducts, remote vaults, mine sites<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>There is no ultimate victor. The selection relies on fire safety criteria and the ability for repair. What is important is that whatever system you choose, it satisfies all three criteria mentioned above: good enclosure protection, corrosion-resisting properties, and removal of any condensation that may occur.<\/p>\n<h2 id=\"specs\">Specification Checklist<\/h2>\n<ul>\n<li>Confirm the tunnel conditions: humidity levels, salt amounts, ventilation, and chemicals applied.<\/li>\n<li>Enclosures and compartments must comply with IP54 at least (it is recommended to comply with IP55 if water is sprayed in tunnel).<\/li>\n<li>ISO 12944 C4 (or C5 for salt tunnels) coating should be specified with dry-film thickness in the contract.<\/li>\n<li>Stainless steel or heavy coated shells should be used if severe corrosion occurs.<\/li>\n<li>Sealed oil preservation should be applied to oil-immersed equipment while dry construction should be utilized in fire-hazard areas.<\/li>\n<li>Anti-condensation heaters, humidity-controlled ventilation with dehumidifying units should be integrated into the project.<\/li>\n<li>Moisture content should also be listed on the data sheet.<\/li>\n<li>Add monitoring: oil moisture sensor, winding temperature sensor, and leak\/condensation sensor.<\/li>\n<\/ul>\n<p style=\"text-align: center;\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-10655\" src=\"https:\/\/subian-electric.com\/wp-content\/uploads\/2026\/08\/Specification-Checklist1.webp\" alt=\"Specification Checklist1\" width=\"1448\" height=\"1086\" \/><\/p>\n<h2 id=\"brands\">Top Brands &amp; Price Comparison<\/h2>\n<p>Manufacturers of tunnel-grade transformers include both international leaders and dedicated producers. The table provides prices for 1,000 kVA dry transformers of 10\/0.4 kV with an IP54+ tunnel grade case and C4 treatment; oil-type transformers will be approximately 35-45 percent cheaper.<\/p>\n<table>\n<thead>\n<tr>\n<th>Marca<\/th>\n<th>Pa\u00eds<\/th>\n<th>Tunnel-Relevant Strengths<\/th>\n<th>Pre\u00e7o Indicativo (USD)<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Schneider Electric<\/td>\n<td>Fran\u00e7a<\/td>\n<td>Strong dry-type and IP55 enclosure portfolio<\/td>\n<td>$22,000\u2013$34,000<\/td>\n<\/tr>\n<tr>\n<td>Siemens<\/td>\n<td>Alemanha<\/td>\n<td>Tunnel infrastructure references, digital monitoring<\/td>\n<td>$23,000\u2013$36,000<\/td>\n<\/tr>\n<tr>\n<td>ABB<\/td>\n<td>Su\u00ed\u00e7a<\/td>\n<td>Broad cast-resin and sealed-tank range<\/td>\n<td>$22,000\u2013$35,000<\/td>\n<\/tr>\n<tr>\n<td>Eaton<\/td>\n<td>EUA<\/td>\n<td>Industrial dry-type depth, custom enclosures<\/td>\n<td>$20,000\u2013$32,000<\/td>\n<\/tr>\n<tr>\n<td>Hitachi Energy<\/td>\n<td>Japan\/Switzerland<\/td>\n<td>Large infrastructure transformer expertise<\/td>\n<td>$24,000\u2013$38,000<\/td>\n<\/tr>\n<tr>\n<td>Jiangsu Subian Electric Power<\/td>\n<td>China<\/td>\n<td>IEC 60076-compliant units with IP54\/55, C4 coating, stainless options<\/td>\n<td>$15,000\u2013$26,000<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>International manufacturers offer exceptional construction practices and comprehensive documentation expertise which are key requirements for projects that have stringent certifications and insurance requirements. Jiangsu Subian Electric Power is an active participant in this field and manufactures IEC 60076-compliant dry-type and oil-immersed transformers that meet the company-specific specifications like IP55 enclosure, C4\/C5 coating, stainless steel options, anti-condensation heating systems, and moisture monitoring, with a price 45-60% lower than that of their European or American counterparts. When it comes to the evaluation of the options for the construction of multiple transformer rooms for ventilation, lighting, and drainage, Subian is presented as a worthy alternative to international companies due to its flexibility in producing customized products and great factory-test witnessing system.<\/p>\n<h2 id=\"faq\">Perguntas Frequentes<\/h2>\n<h3>What IP rating do I need for a transformer in a tunnel?<\/h3>\n<p>The minimum acceptable IP rating for a transformer is IP54, but IP55 is preferable if the transformer will be exposed to water due to cleaning, or water leakages. The meaning of an IP54 rating is that it is dust-tight and protects against splashes of water from any direction. In contrast, IP55 protects against water jets used for cleaning. Installing equipment that operates to a higher IP rating than IP23 costs at least $400\u2013$1,500 more.<\/p>\n<h3>How much does a tunnel-grade transformer cost compared to a standard one?<\/h3>\n<p>The cost of a standard 1000 kVA dry-type transformer can reach $13,000\u2013$18,000. The cost of a tunnel-grade transformer with an IP54\/55 enclosure, C4 coating, and condensation controls is $18,000\u2013$32,000, which means a premium of 15\u201330%. In addition, stainless steel shells add an extra $3,000\u2013$8,000. However, this is a small premium when the total costs are compared with the costs of its mid-life replacement for a critical tunnel infrastructure.<\/p>\n<h3>Is a dry-type or oil-immersed transformer better in a moist tunnel?<\/h3>\n<p>For road and rail tunnels where fire protection is sensitive, the dry-type transformer (cast resin) is the preferred choice, as it is self-extinguishing and poses no risk of spillage of oil. On the other hand, oil-immersed transformers are more cost-efficient for utility ducts, mine workings, and non-access vaults. Thus, it is important to understand that fire protection, maintenance access, and costs are the main determining issues in choosing a transformer type.<\/p>\n<h3>What moisture level in transformer oil is acceptable?<\/h3>\n<p>It is considered that moisture content in transformer oil during the delivery period should not exceed 15-20 ppm. In operation, the oil moisture content is acceptable if it does not exceed 30 ppm. If it ranges from 30 to 50 ppm, more monitoring is required. When the moisture level exceeds 50 ppm, there is a potential risk of formation air bubbles during the operation of the transformer.<\/p>\n<h3>Do anti-condensation heaters really prevent transformer failure?<\/h3>\n<p>Yes, and they are among the best measures of cost-efficiency mentioned in this article. These heaters operate using a thermostat and cost $200-$600.<\/p>\n<h2 id=\"references\">Refer\u00eancias<\/h2>\n<ul>\n<li><a href=\"https:\/\/webstore.iec.ch\" rel=\"nofollow noopener\" target=\"_blank\">IEC 60529 \u2014 Degrees of protection provided by enclosures (IP Code)<\/a> \u2014 the standard defining IP ratings for transformer enclosures and compartments.<\/li>\n<li><a href=\"https:\/\/iec.ch\" rel=\"nofollow noopener\" target=\"_blank\">IEC 60076 series \u2014 Power transformers<\/a> \u2014 base design, testing, and insulation standards for all tunnel transformer specifications.<\/li>\n<li><a href=\"https:\/\/www.iso.org\/standard\/64556.html\" rel=\"nofollow noopener\" target=\"_blank\">ISO 12944 \u2014 Paints and varnishes: Corrosion protection of steel structures<\/a> \u2014 the corrosivity classification (C2\u2013C5) used for tunnel coating specifications.<\/li>\n<li><a href=\"https:\/\/ieeexplore.ieee.org\/document\/8898732\" rel=\"nofollow noopener\" target=\"_blank\">IEEE C57.106 \u2014 Guide for Acceptance and Maintenance of Insulating Mineral Oil<\/a> \u2014 authoritative guidance on oil moisture limits and interpretation.<\/li>\n<li><a href=\"https:\/\/webstore.iec.ch\" rel=\"nofollow noopener\" target=\"_blank\">IEC 60076-11 \u2014 Dry-type power transformers<\/a> \u2014 moisture and enclosure requirements for cast-resin units in humid environments.<\/li>\n<li><a href=\"https:\/\/www.arema.org\" rel=\"nofollow noopener\" target=\"_blank\">AREMA Manual for Railway Engineering<\/a> \u2014 tunnel electrical and ventilation infrastructure guidance used in North American rail projects.<\/li>\n<li><a href=\"https:\/\/subian-electric.com\/pt\/\" rel=\"nofollow\">Jiangsu Subian Electric Power \u2014 official site<\/a> \u2014 manufacturer of IP54\/55, C4-coated tunnel-grade transformers for infrastructure projects.<\/li>\n<\/ul>\n<h2 id=\"conclusion\">Conclus\u00e3o<\/h2>\n<p>Moisture can damage a transformer, but you can reduce the chances of this problem happening by following some recommendations. Recommendation number one is to install the transformer inside a sealed enclosure (IP54 or higher) with waterproof installation. The second suggestion is to coat steel parts of the transformer with materials that can withstand corrosion and humidity (preferably, ISO 12944 C4\/classification degree coating will be appropriate). The third recommendation is to provide ventilation, heating systems, and humidity control (dehumidifiers).<\/p>\n<p>Key points:<\/p>\n<ul>\n<li>IP23\/IP31 enclosures are not good for operation in tunnels; IP54\/IP55 is a must.<\/li>\n<li>Ensure the use of C4 coating (C5 for salt-tunnels) to protect the transformer from corrosion according to ISO 12944.<\/li>\n<li>You still need to pay an additional 15\u201330% for a transformer rated for tunnel operation when buying it; this way you will be ensured that you will have a reliable device for 25 years instead of a malfunctioning one for only 5 years.<\/li>\n<li>Provide the transformer with heating and humidity control: this will help avoid the humidity-related problems while operating the transformer.<\/li>\n<\/ul>","protected":false},"excerpt":{"rendered":"<p>If you visit the switch-room in between the two ends of an urban highway tunnel in the middle of the summer season and see its condition, you would get the answer. The 800kVA transformer, which is the main source of the power of ventilation and lighting system of the tunnel, is located inside a room [&hellip;]<\/p>\n","protected":false},"author":2,"featured_media":10653,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[77],"tags":[],"class_list":["post-10651","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-news"],"blocksy_meta":[],"acf":[],"_links":{"self":[{"href":"https:\/\/subian-electric.com\/pt\/wp-json\/wp\/v2\/posts\/10651","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/subian-electric.com\/pt\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/subian-electric.com\/pt\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/subian-electric.com\/pt\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/subian-electric.com\/pt\/wp-json\/wp\/v2\/comments?post=10651"}],"version-history":[{"count":2,"href":"https:\/\/subian-electric.com\/pt\/wp-json\/wp\/v2\/posts\/10651\/revisions"}],"predecessor-version":[{"id":10909,"href":"https:\/\/subian-electric.com\/pt\/wp-json\/wp\/v2\/posts\/10651\/revisions\/10909"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/subian-electric.com\/pt\/wp-json\/wp\/v2\/media\/10653"}],"wp:attachment":[{"href":"https:\/\/subian-electric.com\/pt\/wp-json\/wp\/v2\/media?parent=10651"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/subian-electric.com\/pt\/wp-json\/wp\/v2\/categories?post=10651"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/subian-electric.com\/pt\/wp-json\/wp\/v2\/tags?post=10651"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}