{"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\/fr\/news\/how-to-choose-transformers-for-moist-tunnels-focus-on-these-3-points\/","title":{"rendered":"Comment Choisir des Transformateurs pour des Tunnels Humides ? Concentrez-vous sur Ces 3 Points"},"content":{"rendered":"<p>Si vous visitez la salle de commutation entre les deux extr\u00e9mit\u00e9s d'un tunnel urbain en plein \u00e9t\u00e9 et que vous voyez son \u00e9tat, vous obtiendrez la r\u00e9ponse. Le transformateur de 800 kVA, qui est la principale source d'alimentation du syst\u00e8me de ventilation et d'\u00e9clairage du tunnel, est situ\u00e9 \u00e0 l'int\u00e9rieur d'une pi\u00e8ce avec un niveau d'humidit\u00e9 sup\u00e9rieur \u00e0 85% depuis des mois. Chaque nuit, de la condensation se forme sur la surface du r\u00e9servoir. Les murs de la pi\u00e8ce montrent des taches caus\u00e9es par des d\u00e9p\u00f4ts de sel dus aux mat\u00e9riaux de d\u00e9neigement d\u00e9charg\u00e9s de la chauss\u00e9e. L'historique de maintenance indique trois cas de d\u00e9connexion des relais cette ann\u00e9e en raison de probl\u00e8mes qui provoquent la formation de courts-circuits sur les barres collectrices basse tension en raison de l'humidit\u00e9. L'analyse de l'huile montre qu'elle contient 42 ppm d'eau, ce qui est sup\u00e9rieur au taux autoris\u00e9 de 30 ppm et provoque une d\u00e9gradation de l'isolation en papier.<\/p>\n<p>Les tunnels sont parmi les endroits les plus difficiles pour utiliser des transformateurs en raison de l'humidit\u00e9 qu'ils contiennent. Cet article vous pr\u00e9sente 3 probl\u00e8mes importants \u00e0 garder \u00e0 l'esprit lors de la s\u00e9lection de transformateurs pour les tunnels : protection de l'isolation et de l'enveloppe, s\u00e9lection des mat\u00e9riaux et protection contre la corrosion, et contr\u00f4le de la ventilation et de la condensation.<\/p>\n<blockquote><p>La r\u00e9ponse br\u00e8ve est la suivante : lors de la s\u00e9lection d'un transformateur pour des tunnels humides, trois \u00e9l\u00e9ments doivent \u00eatre pris en compte : (1) Protection par enveloppe et isolation \u2013 pour les types de transformateurs secs, des enveloppes class\u00e9es IP54 et IP55 doivent \u00eatre sp\u00e9cifi\u00e9es. En cas de transformateurs immerg\u00e9s dans l'huile, des r\u00e9servoirs scell\u00e9s en mat\u00e9riaux r\u00e9sistants \u00e0 la corrosion doivent \u00eatre sp\u00e9cifi\u00e9s ; (2) Mat\u00e9riaux r\u00e9sistants \u00e0 la corrosion \u2013 enveloppes en acier inoxydable ou en mat\u00e9riaux rev\u00eatus de poudre de haute r\u00e9sistance, finitions class\u00e9es pour la classe de corrosivit\u00e9 C3\/C4 selon la norme ISO 12944, isolations tropicalis\u00e9es avec des niveaux d'humidit\u00e9 \u00e9lev\u00e9s ; (3) Ventilation et pr\u00e9vention de la condensation \u2013 \u00e9change d'air contr\u00f4l\u00e9, chauffages anti-condensation ; contr\u00f4leurs d'humidit\u00e9.<\/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\">Pourquoi les tunnels humides d\u00e9truisent les transformateurs<\/h2>\n<p>La d\u00e9faillance d'un transformateur dans des environnements humides n'est g\u00e9n\u00e9ralement pas un accident \u00e9lectrique instantan\u00e9 \u2014 c'est plut\u00f4t un processus chimique et physique graduel. Voici les principales causes :<\/p>\n<ul>\n<li>Humidit\u00e9 dans l'isolation : Dans les transformateurs immerg\u00e9s dans l'huile, l'humidit\u00e9 p\u00e9n\u00e8tre par les respirateurs, les joints et la condensation. Des niveaux d'humidit\u00e9 sup\u00e9rieurs \u00e0 30 ppm dans l'huile du transformateur acc\u00e9l\u00e8rent le vieillissement de l'isolation en papier, r\u00e9duisant sa dur\u00e9e de vie de moiti\u00e9 \u00e0 chaque fois que l'humidit\u00e9 est deux fois sup\u00e9rieure \u00e0 la normale. \u00c0 50\u201360 ppm, la formation de bulles peut se produire lors de la surcharge et entra\u00eener une d\u00e9faillance di\u00e9lectrique.<\/li>\n<li>Suivi de surface et propagation : Sur les enroulements et les bushing de type sec, l'humidit\u00e9 associ\u00e9e \u00e0 la poussi\u00e8re ou au sel cr\u00e9e des canaux conducteurs le long de la surface qui entra\u00eenent des d\u00e9charges partielles et des arcs.<\/li>\n<li>Corrosion du r\u00e9servoir, des accessoires et des connexions : Le condensat contenant du sel attaque les r\u00e9servoirs, les ailettes de radiateur, les accessoires de c\u00e2ble et les connexions boulonn\u00e9es, augmentant la r\u00e9sistance de contact et provoquant finalement des joints chauds.<\/li>\n<li>Condensation des compartiments de contr\u00f4le et basse tension : Les fluctuations de temp\u00e9rature font que l'eau se condense sur les barres omnibus et les modules \u00e9lectroniques, et un seul incident de condensation peut entra\u00eener un arc entre phases.<\/li>\n<\/ul>\n<p>Et les statistiques confirment la physique : les transformateurs situ\u00e9s sur des sites c\u00f4tiers et dans des tunnels pr\u00e9sentent un taux de d\u00e9faillance 2 \u00e0 3 fois plus \u00e9lev\u00e9 par rapport aux unit\u00e9s dans des zones s\u00e8ches \u00e0 l'int\u00e9rieur des terres, le vieillissement de l'isolation induit par l'humidit\u00e9 \u00e9tant la principale cause de d\u00e9faillance constat\u00e9e lors des enqu\u00eates judiciaires. La solution n'est pas l'entretien \u2014 c'est la sp\u00e9cification correcte lors de l'acquisition.<\/p>\n<h2 id=\"point1\">Point 1 : Protection de l'enceinte et de l'isolation<\/h2>\n<p>La question principale est de savoir comment emp\u00eacher l'humidit\u00e9 d'affecter l'isolation. En termes de langage de sp\u00e9cification, il est important d'\u00eatre pr\u00e9cis :<\/p>\n<table>\n<thead>\n<tr>\n<th>\u00c9l\u00e9ment<\/th>\n<th>Norme \/ Exigence<\/th>\n<th>Sp\u00e9cification de qualit\u00e9 tunnel<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Enceinte de type sec<\/td>\n<td>Classe de protection IP selon IEC 60529<\/td>\n<td>IP54 minimum ; IP55 lorsque des projections d'eau sont possibles<\/td>\n<\/tr>\n<tr>\n<td>R\u00e9servoir immerg\u00e9 dans l'huile<\/td>\n<td>IEC 60529 + conception scell\u00e9e<\/td>\n<td>R\u00e9servoir scell\u00e9 avec syst\u00e8me de pr\u00e9servation de l'huile (couverture d'azote ou type adsorption de gaz)<\/td>\n<\/tr>\n<tr>\n<td>Bagues et terminaisons<\/td>\n<td>IEC 60529 \/ distance de creepage selon IEC 60076<\/td>\n<td>Distances de creepage \u00e9tendues, sheds en silicone ou \u00e9poxy, bo\u00eetes de c\u00e2bles IP54<\/td>\n<\/tr>\n<tr>\n<td>Compartiments de contr\u00f4le \/ basse tension<\/td>\n<td>IEC 60529<\/td>\n<td>Compartiments IP55 avec portes \u00e0 joint et filtres \u00e0 respirateur<\/td>\n<\/tr>\n<tr>\n<td>Syst\u00e8me d'isolation<\/td>\n<td>IEC 60076-11 (sec), IEC 60076-1 (huile)<\/td>\n<td>Isolation tropicalis\u00e9e, limites de teneur en humidit\u00e9 indiqu\u00e9es dans la fiche technique<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>L'erreur habituelle est de sp\u00e9cifier des enceintes IP23 ou IP31 \u2014 bien qu'elles puissent convenir \u00e0 un usage industriel \u00e0 l'int\u00e9rieur, elles ne fonctionneront pas dans des cas expos\u00e9s \u00e0 des conditions d'humidit\u00e9 constante d'un tunnel. Chaque pourcentage d'am\u00e9lioration IP co\u00fbte g\u00e9n\u00e9ralement entre 400 et 1 500 dollars par unit\u00e9, et pourtant, c'est pr\u00e9cis\u00e9ment la distinction entre IP31 et IP55 qui d\u00e9termine si un transformateur de tunnel durera cinq ans.<\/p>\n<h2 id=\"point2\">Point 2 : R\u00e9sistance \u00e0 la corrosion et mat\u00e9riaux<\/h2>\n<p>Le deuxi\u00e8me point important dans la prise de d\u00e9cision est le choix des mat\u00e9riaux. Dans un environnement de tunnel humide, la finition de surface et la qualit\u00e9 du m\u00e9tal sont tout aussi essentielles que la conception des syst\u00e8mes \u00e9lectriques. La norme applicable est ISO 12944 (peintures et rev\u00eatements pour constructions en acier) qui divise la corrosivit\u00e9 atmosph\u00e9rique en cat\u00e9gories allant de C1 (int\u00e9rieurs ventil\u00e9s) \u00e0 C5-X (tr\u00e8s forte). Les tunnels avec des \u00e9claboussures provenant des voitures sont g\u00e9n\u00e9ralement reconnus comme C3 ou C4, tandis que les tunnels riches en sel peuvent atteindre la cat\u00e9gorie C5-I.<\/p>\n<table>\n<thead>\n<tr>\n<th>Composant<\/th>\n<th>Sp\u00e9cification standard<\/th>\n<th>Sp\u00e9cification de qualit\u00e9 tunnel<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Rev\u00eatement du r\u00e9servoir et de l'enceinte<\/td>\n<td>ISO 12944 C2\/C3, couche unique<\/td>\n<td>Syst\u00e8me de rev\u00eatement C4 ou C5, \u00e9paisseur minimale de film sec de 120 \u00e0 240 \u00b5m<\/td>\n<\/tr>\n<tr>\n<td>Mat\u00e9riau de la coque de l'enceinte<\/td>\n<td>Acier lamin\u00e9 \u00e0 froid, peinture<\/td>\n<td>Acier inoxydable (304\/316) ou galvanis\u00e9 \u00e0 chaud + rev\u00eatement en poudre \u00e9pais<\/td>\n<\/tr>\n<tr>\n<td>Fixations et accessoires<\/td>\n<td>Acier zingu\u00e9<\/td>\n<td>Fixations en acier inoxydable, passe-c\u00e2bles en laiton ou en acier inoxydable<\/td>\n<\/tr>\n<tr>\n<td>Radiateurs \/ ailettes de refroidissement<\/td>\n<td>Acier au carbone standard<\/td>\n<td>Ailettes rev\u00eatues ou marge de refroidissement augment\u00e9e pour compenser la perte de rev\u00eatement<\/td>\n<\/tr>\n<tr>\n<td>Respirateurs en gel de silice<\/td>\n<td>Norme<\/td>\n<td>Gel de silice de qualit\u00e9 r\u00e9actif avec indicateur de couleur, volume plus important<\/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>Taper<\/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>Dry-type (cast resin)<\/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>Facteur<\/th>\n<th>Type sec (r\u00e9sine coul\u00e9e)<\/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>Maintenance<\/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\">Meilleures marques et comparaison des prix<\/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>Marque<\/th>\n<th>Pays<\/th>\n<th>Tunnel-Relevant Strengths<\/th>\n<th>Prix indicatif (USD)<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Schneider Electric<\/td>\n<td>France<\/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>Allemagne<\/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>Suisse<\/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>\u00c9tats-Unis<\/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>Chine<\/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\">Questions Fr\u00e9quemment Pos\u00e9es<\/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\">R\u00e9f\u00e9rences<\/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 s\u00e9rie \u2014 Transformateurs de puissance<\/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\/fr\/\" 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\">Conclusion<\/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\/fr\/wp-json\/wp\/v2\/posts\/10651","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/subian-electric.com\/fr\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/subian-electric.com\/fr\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/subian-electric.com\/fr\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/subian-electric.com\/fr\/wp-json\/wp\/v2\/comments?post=10651"}],"version-history":[{"count":2,"href":"https:\/\/subian-electric.com\/fr\/wp-json\/wp\/v2\/posts\/10651\/revisions"}],"predecessor-version":[{"id":10909,"href":"https:\/\/subian-electric.com\/fr\/wp-json\/wp\/v2\/posts\/10651\/revisions\/10909"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/subian-electric.com\/fr\/wp-json\/wp\/v2\/media\/10653"}],"wp:attachment":[{"href":"https:\/\/subian-electric.com\/fr\/wp-json\/wp\/v2\/media?parent=10651"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/subian-electric.com\/fr\/wp-json\/wp\/v2\/categories?post=10651"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/subian-electric.com\/fr\/wp-json\/wp\/v2\/tags?post=10651"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}