{"id":2209,"date":"2026-10-08T22:36:04","date_gmt":"2026-10-08T14:36:04","guid":{"rendered":"https:\/\/jutrion.com\/?p=2209"},"modified":"2026-10-08T22:36:07","modified_gmt":"2026-10-08T14:36:07","slug":"275v-vs-320v-vs-385v-spd-choose-correct-uc","status":"publish","type":"post","link":"https:\/\/jutrion.com\/fr\/275v-vs-320v-vs-385v-spd-choose-correct-uc\/","title":{"rendered":"275 V vs 320 V vs 385 V SPD : Comment choisir le bon Uc"},"content":{"rendered":"<h2 class=\"wp-block-heading has-palette-color-9-color has-text-color has-link-color has-large-font-size wp-elements-1\">275 V, 320 V ou 385 V : La r\u00e9ponse courte<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Pour une installation AC 230\/400 V, un SPD 275 V est souvent le premier candidat lorsque son mode de protection voit normalement environ 230 V, mais ce n'est pas un choix automatique pour chaque r\u00e9seau. Utilisez 320 V lorsque la conception approuv\u00e9e n\u00e9cessite une marge de tension continue ou de surtension temporaire plus importante, et utilisez 385 V uniquement lorsque le mode de protection r\u00e9el, l'agencement de mise \u00e0 la terre et les donn\u00e9es du fabricant justifient cette classification plus \u00e9lev\u00e9e. Ne s\u00e9lectionnez pas uniquement en fonction de la tension nominale du syst\u00e8me.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">La bonne U<sub>c<\/sub> est la plus basse tension maximale continue de fonctionnement approuv\u00e9e qui reste au-dessus de la plus haute tension que le SPD peut subir en continu dans son mode connect\u00e9. Elle doit \u00e9galement survivre aux conditions de surtension temporaire attendues \u00e0 ce point. Apr\u00e8s avoir s\u00e9lectionn\u00e9 U<sub>c<\/sub>, v\u00e9rifiez que le niveau de protection de tension r\u00e9sultant U<sub>p<\/sub> est toujours suffisamment bas pour l'\u00e9quipement prot\u00e9g\u00e9.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Cette derni\u00e8re v\u00e9rification est importante car U<sub>c<\/sub> n'est pas une classification de courant de surtension. Une cartouche 385 V n'est pas une version plus robuste d'une cartouche 275 V \u00e0 tous \u00e9gards. Elle peut tol\u00e9rer une tension de fr\u00e9quence de puissance soutenue plus \u00e9lev\u00e9e, mais elle peut commencer \u00e0 limiter \u00e0 une tension plus \u00e9lev\u00e9e et peut avoir une U<sub>p<\/sub>. d\u00e9clar\u00e9e plus \u00e9lev\u00e9e. Le meilleur choix \u00e9quilibre donc la stabilit\u00e9 du service par rapport au niveau de protection.<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"341\" src=\"https:\/\/jutrion.com\/wp-content\/uploads\/2026\/10\/01-spd-uc-275v-320v-385v-comparison-1024x341.webp\" alt=\"\" class=\"wp-image-2231\" srcset=\"https:\/\/jutrion.com\/wp-content\/uploads\/2026\/10\/01-spd-uc-275v-320v-385v-comparison-1024x341.webp 1024w, https:\/\/jutrion.com\/wp-content\/uploads\/2026\/10\/01-spd-uc-275v-320v-385v-comparison-300x100.webp 300w, https:\/\/jutrion.com\/wp-content\/uploads\/2026\/10\/01-spd-uc-275v-320v-385v-comparison-768x256.webp 768w, https:\/\/jutrion.com\/wp-content\/uploads\/2026\/10\/01-spd-uc-275v-320v-385v-comparison-18x6.webp 18w, https:\/\/jutrion.com\/wp-content\/uploads\/2026\/10\/01-spd-uc-275v-320v-385v-comparison.webp 1200w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\"><code><em>Comparaison des classifications Uc des SPD 275 V, 320 V et 385 V sur un circuit 230 V ligne-\u00e0-neutre.<\/em><\/code><\/figcaption><\/figure>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<h2 class=\"wp-block-heading has-palette-color-9-color has-text-color has-link-color has-large-font-size wp-elements-2\">Ce que U<sub>c<\/sub> signifie r\u00e9ellement sur un SPD AC<\/h2>\n<\/blockquote>\n\n\n\n<p class=\"wp-block-paragraph\">U<sub>c<\/sub> est la tension maximale continue de fonctionnement qui peut \u00eatre appliqu\u00e9e aux bornes du SPD dans les conditions d\u00e9clar\u00e9es par le fabricant. Sur un produit AC, il s'agit normalement d'une valeur efficace \u00e0 la fr\u00e9quence d\u00e9clar\u00e9e. Pendant le fonctionnement normal, le SPD doit rester stable \u00e0 cette tension sans se comporter comme si chaque cr\u00eate du r\u00e9seau \u00e9tait une surtension.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Cette d\u00e9finition explique pourquoi U<sub>c<\/sub> doit \u00eatre lu \u00e0 travers un mode de protection sp\u00e9cifique :<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>L\u2013N :<\/strong> phase \u00e0 neutre ;<\/li>\n\n\n\n<li><strong>L\u2013PE :<\/strong> phase \u00e0 terre de protection ;<\/li>\n\n\n\n<li><strong>N\u2013PE :<\/strong> neutre \u00e0 terre de protection ; ou<\/li>\n\n\n\n<li><strong>L\u2013L :<\/strong> phase \u00e0 phase dans un agencement con\u00e7u pour ce mode.<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">Un r\u00e9seau triphas\u00e9 peut \u00eatre d\u00e9crit comme 230\/400 V, pourtant la tension \u00e0 travers un module SPD individuel peut \u00eatre de 230 V ou 400 V selon l'endroit o\u00f9 ce module est connect\u00e9. L'\u00e9tiquette du syst\u00e8me et l'\u00e9tiquette de la cartouche ne sont donc pas interchangeables.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Ne confondez pas U<sub>c<\/sub> avec les autres chiffres imprim\u00e9s sur un SPD :<\/p>\n\n\n\n<figure class=\"wp-block-table jutrion-table\"><table class=\"has-fixed-layout\"><thead><tr><th>Marquage<\/th><th>Ce qu'il d\u00e9crit<\/th><th>Ce qu'il ne prouve pas<\/th><\/tr><\/thead><tbody><tr><td>U<sub>c<\/sub><\/td><td>Tension maximale qui peut rester en continu \u00e0 travers le mode de protection d\u00e9clar\u00e9<\/td><td>Capacit\u00e9 de d\u00e9charge de surtension ou tension d\u00e9livr\u00e9e \u00e0 la charge pendant une surtension<\/td><\/tr><tr><td>U<sub>p<\/sub><\/td><td>Niveau de protection de tension d\u00e9clar\u00e9 sous des conditions de test d'impulsion sp\u00e9cifi\u00e9es<\/td><td>Tol\u00e9rance de tension de fonctionnement continue<\/td><\/tr><tr><td>I<sub>n<\/sub><\/td><td>Devoir de courant de d\u00e9charge nominal utilisant la forme d'onde 8\/20 \u00b5s<\/td><td>Capacit\u00e9 de foudre directe<\/td><\/tr><tr><td>I<sub>max<\/sub><\/td><td>Courant de d\u00e9charge maximal pour un SPD de Type 2 sous le test 8\/20 \u00b5s d\u00e9clar\u00e9<\/td><td>Devoir r\u00e9p\u00e9t\u00e9 \u00e0 cette valeur maximale<\/td><\/tr><tr><td>I<sub>imp<\/sub><\/td><td>Devoir de courant d'impulsion associ\u00e9 aux tests de Type 1 et \u00e0 la forme d'onde 10\/350 \u00b5s<\/td><td>Un substitut pour U<sub>c<\/sub> ou U<sub>p<\/sub><\/td><\/tr><tr><td>U<sub>T<\/sub> \/ donn\u00e9es TOV<\/td><td>Comportement sous une surtension temporaire de fr\u00e9quence de puissance sp\u00e9cifi\u00e9e pour une dur\u00e9e donn\u00e9e<\/td><td>Permission de fonctionner en continu \u00e0 cette tension<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">Pour une explication plus large des types de SPD, des classifications de courant de d\u00e9charge et des positions d'installation, utilisez le <a href=\"https:\/\/jutrion.com\/fr\/surge-protective-device-guide\/\">guide des dispositifs de protection contre les surtensions JUTRION<\/a>. Cet article se concentre sur la d\u00e9cision plus \u00e9troite : choisir parmi les valeurs U de 275 V, 320 V et 385 V<sub>c<\/sub> .<\/p>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<h2 class=\"wp-block-heading has-palette-color-9-color has-text-color has-link-color has-large-font-size wp-elements-3\">Pourquoi les trois classifications apparaissent dans les projets 230\/400 V<\/h2>\n<\/blockquote>\n\n\n\n<p class=\"wp-block-paragraph\">Les trois classifications existent parce qu'un syst\u00e8me basse tension ne pr\u00e9sente pas une tension parfaitement fixe dans toutes les conditions de fonctionnement et de d\u00e9faut. La tol\u00e9rance d'alimentation, la r\u00e9gulation de la tension, la distorsion harmonique, le d\u00e9placement du neutre, les d\u00e9fauts \u00e0 la terre et l'arrangement de mise \u00e0 la terre peuvent modifier la tension appliqu\u00e9e \u00e0 un mode de protection. Les familles de produits diff\u00e8rent \u00e9galement par leur comportement TOV et leur technologie interne.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Pour une alimentation nominale de 230 V phase-\u00e0-neutre, le rapport simple est :<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>275 \/ 230 = 1,20, 320 \/ 230 = 1,39, et 385 \/ 230 = 1,67.<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Ces rapports sont utiles pour voir la marge de tension continue croissante, mais ils ne constituent pas une formule de s\u00e9lection compl\u00e8te. Ils ne d\u00e9crivent pas la tension maximale \u00e0 l'\u00e9tat stable du site, le mode de protection, ou comment le SPD se comporte pendant un TOV. Deux SPDs avec le m\u00eame U<sub>c<\/sub> peuvent \u00e9galement avoir des U<sub>T<\/sub>, la U<sub>p<\/sub>, des donn\u00e9es de protection de secours et de d\u00e9connexion.<\/p>\n\n\n\n<figure class=\"wp-block-table jutrion-table\"><table class=\"has-fixed-layout\"><thead><tr><th>U<sub>c<\/sub> classe<\/th><th>Raison typique pour laquelle il entre dans la liste restreinte<\/th><th>Principal avantage<\/th><th>V\u00e9rification principale avant approbation<\/th><\/tr><\/thead><tbody><tr><td>275 V CA<\/td><td>Le mode de protection voit normalement environ 230 V et les donn\u00e9es TOV du produit conviennent au r\u00e9seau<\/td><td>Une marge de tension plus stricte soutient souvent un niveau de protection relativement bas<\/td><td>Peut-il rester stable \u00e0 la tension continue la plus \u00e9lev\u00e9e du site et survivre au TOV sp\u00e9cifi\u00e9 ?<\/td><\/tr><tr><td>320 V CA<\/td><td>La conception n\u00e9cessite une marge de tension d'exploitation suppl\u00e9mentaire, ou le fabricant attribue cette classe \u00e0 l'agencement de r\u00e9seau requis<\/td><td>Plus de tol\u00e9rance \u00e0 l'\u00e9l\u00e9vation de tension soutenue qu'une classe de 275 V<\/td><td>Son U<sub>p<\/sub> est-il toujours coordonn\u00e9 avec la tension d'impulsion de r\u00e9sistance de l'\u00e9quipement ?<\/td><\/tr><tr><td>385 V CA<\/td><td>Le mode connect\u00e9 ou la strat\u00e9gie TOV approuv\u00e9e n\u00e9cessite une marge de tension substantiellement plus \u00e9lev\u00e9e<\/td><td>Risque r\u00e9duit de fonctionnement ind\u00e9sirable d\u00fb \u00e0 une tension de fr\u00e9quence de puissance \u00e9lev\u00e9e<\/td><td>La classe sup\u00e9rieure laisse-t-elle un niveau de protection efficace suffisamment bas \u00e0 la charge ?<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">Il s'agit d'un tableau de filtrage, pas d'un tableau de substitution universel. Un appareil de 320 V ne peut pas automatiquement remplacer un appareil de 275 V, et un appareil de 385 V ne peut pas \u00eatre approuv\u00e9 simplement parce qu'il est moins susceptible de r\u00e9agir \u00e0 une tension de r\u00e9seau \u00e9lev\u00e9e.<\/p>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<h2 class=\"wp-block-heading has-palette-color-9-color has-text-color has-link-color has-large-font-size wp-elements-4\">Commencez par la tension \u00e0 travers chaque mode de protection<\/h2>\n<\/blockquote>\n\n\n\n<p class=\"wp-block-paragraph\">Dessinez la connexion du SPD avant de choisir la cartouche. Marquez la tension normale \u00e0 travers chaque mode et demandez quelle tension peut appara\u00eetre l\u00e0 pendant les \u00e9tats de fonctionnement et de d\u00e9faut cr\u00e9dibles d\u00e9finis par le projet.<\/p>\n\n\n\n<h3 class=\"wp-block-heading has-palette-color-9-color has-text-color has-link-color has-medium-font-size wp-elements-5\">Protection monophas\u00e9e 230 V, L\u2013N<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Un SPD connect\u00e9 de la ligne au neutre voit normalement la tension phase-\u00e0-neutre. Dans un syst\u00e8me 230 V ordinaire et correctement r\u00e9gul\u00e9, 275 V est couramment s\u00e9lectionn\u00e9. L'approbation d\u00e9pend toujours de la plage d'alimentation autoris\u00e9e, des mesures sur site lorsque cela est pertinent, des exigences TOV et de la fiche technique exacte.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Si le site fonctionne r\u00e9guli\u00e8rement pr\u00e8s ou au-dessus de la limite sup\u00e9rieure suppos\u00e9e par la conception, s\u00e9lectionner 275 V uniquement \u00e0 partir de l'\u00e9tiquette nominale peut entra\u00eener un vieillissement acc\u00e9l\u00e9r\u00e9 ou un fonctionnement inutile du disjoncteur thermique. La r\u00e9ponse technique n'est pas automatiquement \u201c installer 385 V \u201d. D\u00e9terminez d'abord si la tension \u00e9lev\u00e9e est une condition de fonctionnement valide, un probl\u00e8me de qualit\u00e9 d'alimentation, un d\u00e9faut de neutre ou une application en dehors de la conception originale.<\/p>\n\n\n\n<h3 class=\"wp-block-heading has-palette-color-9-color has-text-color has-link-color has-medium-font-size wp-elements-6\">Protection triphas\u00e9e 230\/400 V, L\u2013N ou L\u2013PE<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Dans un syst\u00e8me en \u00e9toile 230\/400 V, chaque phase est d'environ 230 V au neutre et d'environ 400 V \u00e0 une autre phase. Un module connect\u00e9 L\u2013N n'est donc pas continuellement expos\u00e9 \u00e0 400 V pendant le fonctionnement normal. Un module connect\u00e9 dans un autre mode peut faire face \u00e0 une exigence diff\u00e9rente.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Cette distinction est la raison pour laquelle le nombre de p\u00f4les ne s\u00e9lectionne pas U<sub>c<\/sub>. \u201c Un SPD \u00e0 quatre p\u00f4les pour un panneau de 400 V \u201d est incomplet. La sp\u00e9cification doit indiquer la configuration du r\u00e9seau et le circuit de protection, tel que 3+1 ou 4+0, et identifier la tension \u00e0 travers chaque module.<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"341\" src=\"https:\/\/jutrion.com\/wp-content\/uploads\/2026\/10\/02-three-phase-spd-3-plus-1-protection-modes-1024x341.webp\" alt=\"\" class=\"wp-image-2232\" srcset=\"https:\/\/jutrion.com\/wp-content\/uploads\/2026\/10\/02-three-phase-spd-3-plus-1-protection-modes-1024x341.webp 1024w, https:\/\/jutrion.com\/wp-content\/uploads\/2026\/10\/02-three-phase-spd-3-plus-1-protection-modes-300x100.webp 300w, https:\/\/jutrion.com\/wp-content\/uploads\/2026\/10\/02-three-phase-spd-3-plus-1-protection-modes-768x256.webp 768w, https:\/\/jutrion.com\/wp-content\/uploads\/2026\/10\/02-three-phase-spd-3-plus-1-protection-modes-18x6.webp 18w, https:\/\/jutrion.com\/wp-content\/uploads\/2026\/10\/02-three-phase-spd-3-plus-1-protection-modes.webp 1200w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\"><code><em>Arrangement SPD triphas\u00e9 3+1 avec L1, L2 et L3 prot\u00e9g\u00e9s \u00e0 la terre et un module N-PE s\u00e9par\u00e9.<\/em><\/code><\/figcaption><\/figure>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<h2 class=\"wp-block-heading has-palette-color-9-color has-text-color has-link-color has-large-font-size wp-elements-7\">Syst\u00e8me de mise \u00e0 la terre et arrangement de circuit Changer la r\u00e9ponse<\/h2>\n<\/blockquote>\n\n\n\n<p class=\"wp-block-paragraph\">La m\u00eame alimentation nominale de 230\/400 V peut n\u00e9cessiter un assemblage SPD diff\u00e9rent selon qu'il s'agit de TN-C, TN-S, TT ou IT. La question importante n'est pas seulement combien de modules sont install\u00e9s, mais quels composants sont connect\u00e9s entre quels conducteurs.<\/p>\n\n\n\n<h3 class=\"wp-block-heading has-palette-color-9-color has-text-color has-link-color has-medium-font-size wp-elements-8\">Syst\u00e8mes TN<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Les syst\u00e8mes TN-C et TN-S ont diff\u00e9rents points de connexion PEN ou N\/PE, donc utilisez un assemblage d\u00e9clar\u00e9 pour l'arrangement TN sp\u00e9cifique. Une cartouche de 275 V est courante pour un mode de protection de 230 V, mais ses performances TOV doivent toujours \u00eatre v\u00e9rifi\u00e9es ; les variantes de 320 V ou 385 V ne sont utilis\u00e9es que lorsque la marge de tension continue ou de TOV requise les supporte.<\/p>\n\n\n\n<h3 class=\"wp-block-heading has-palette-color-9-color has-text-color has-link-color has-medium-font-size wp-elements-9\">Syst\u00e8mes TT et circuits 3+1<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Un arrangement 3+1 place couramment des composants limitant la tension de la phase \u00e0 la terre et un composant bas\u00e9 sur un \u00e9cart de \u00e9tincelle de la terre \u00e0 PE. Les cartouches de phase sont donc s\u00e9lectionn\u00e9es pour un fonctionnement L\u2013N ; le composant N\u2013PE a des donn\u00e9es diff\u00e9rentes. Cet arrangement peut contr\u00f4ler les cons\u00e9quences de TOV dans les syst\u00e8mes TT, mais il doit suivre la norme d'installation applicable et les instructions du fabricant.<\/p>\n\n\n\n<h3 class=\"wp-block-heading has-palette-color-9-color has-text-color has-link-color has-medium-font-size wp-elements-10\">Syst\u00e8mes IT<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Dans un syst\u00e8me IT, les conducteurs sains peuvent augmenter par rapport \u00e0 la terre apr\u00e8s la premi\u00e8re faute \u00e0 la terre. Ne sp\u00e9cifiez pas une cartouche L\u2013PE de 275 V uniquement parce que les charges sont appel\u00e9es 230 V. Utilisez un assemblage d\u00e9clar\u00e9 pour l'arrangement IT et v\u00e9rifiez la tension conducteur-terre, les modes de protection et le comportement TOV.<\/p>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<h2 class=\"wp-block-heading has-palette-color-9-color has-text-color has-link-color has-large-font-size wp-elements-11\">Le v\u00e9ritable compromis : vieillissement nuisible contre niveau de protection<\/h2>\n<\/blockquote>\n\n\n\n<p class=\"wp-block-paragraph\">Choisir U<sub>c<\/sub> trop bas et le choisir trop haut cr\u00e9e diff\u00e9rents probl\u00e8mes.<\/p>\n\n\n\n<h3 class=\"wp-block-heading has-palette-color-9-color has-text-color has-link-color has-medium-font-size wp-elements-12\">Si U<sub>c<\/sub> est trop bas<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Un varistor \u00e0 oxyde m\u00e9tallique est d\u00e9pendant de la tension. Un fonctionnement r\u00e9p\u00e9t\u00e9 ou soutenu trop pr\u00e8s de sa limite continue peut augmenter les fuites, la temp\u00e9rature et le vieillissement. Une surtension temporaire en dehors de la capacit\u00e9 d\u00e9clar\u00e9e peut provoquer le fonctionnement du disjoncteur thermique interne, laissant le circuit en aval sous tension mais plus prot\u00e9g\u00e9 contre les surtensions. Dans un d\u00e9calage s\u00e9v\u00e8re, la d\u00e9faillance peut \u00eatre dangereuse \u00e0 moins que le produit et la protection de secours ne la d\u00e9gagent correctement.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Un indicateur rouge peu apr\u00e8s la mise en service ne prouve pas n\u00e9cessairement que le site a subi un \u00e9v\u00e9nement exceptionnel de foudre. L'enqu\u00eate doit inclure la tension en r\u00e9gime permanent, l'int\u00e9grit\u00e9 du neutre, le c\u00e2blage, l'exposition TOV, la protection de secours et si le U install\u00e9<sub>c<\/sub> et le circuit correspondent au r\u00e9seau.<\/p>\n\n\n\n<h3 class=\"wp-block-heading has-palette-color-9-color has-text-color has-link-color has-medium-font-size wp-elements-13\">Si U<sub>c<\/sub> est trop \u00e9lev\u00e9<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">A higher-U<sub>c<\/sub> varistor normally begins significant conduction at a higher voltage. Depending on the product design, this can raise U<sub>p<\/sub>. For example, one manufacturer\u2019s otherwise comparable single-pole Type 2 family declares U<sub>p<\/sub> at no more than 1.5 kV for its 275 V and 320 V versions, but no more than 1.75 kV for its 385 V version. That is a product example, not a universal conversion rule, but it shows why the higher number is not automatically superior.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">The relevant protection at the load is not just the catalogue U<sub>p<\/sub>. Connection-lead inductance adds voltage while surge current rises. Long conductors can erase the apparent advantage of a lower U<sub>p<\/sub>. U<sub>c<\/sub>, la U<sub>p<\/sub>, conductor length and equipment impulse withstand voltage must therefore be coordinated together.<\/p>\n\n\n\n<blockquote class=\"wp-block-quote jutrion-info-box is-layout-flow wp-block-quote-is-layout-flow\">\n<p class=\"wp-block-paragraph\"><strong>Selection principle:<\/strong> choose the lowest U<sub>c<\/sub> class that is approved for the maximum continuous voltage, protection mode, earthing arrangement and TOV duty. Then confirm that its U<sub>p<\/sub> and installed lead voltage remain below the protected equipment\u2019s impulse withstand requirement with an adequate margin.<\/p>\n<\/blockquote>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"341\" src=\"https:\/\/jutrion.com\/wp-content\/uploads\/2026\/10\/03-spd-uc-tov-up-selection-tradeoff-1024x341.webp\" alt=\"\" class=\"wp-image-2235\" srcset=\"https:\/\/jutrion.com\/wp-content\/uploads\/2026\/10\/03-spd-uc-tov-up-selection-tradeoff-1024x341.webp 1024w, https:\/\/jutrion.com\/wp-content\/uploads\/2026\/10\/03-spd-uc-tov-up-selection-tradeoff-300x100.webp 300w, https:\/\/jutrion.com\/wp-content\/uploads\/2026\/10\/03-spd-uc-tov-up-selection-tradeoff-768x256.webp 768w, https:\/\/jutrion.com\/wp-content\/uploads\/2026\/10\/03-spd-uc-tov-up-selection-tradeoff-18x6.webp 18w, https:\/\/jutrion.com\/wp-content\/uploads\/2026\/10\/03-spd-uc-tov-up-selection-tradeoff.webp 1200w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\"><code><em>SPD Uc selection trade-off between low-voltage ageing and a higher downstream voltage protection level.<\/em><\/code><\/figcaption><\/figure>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<h2 class=\"wp-block-heading has-palette-color-9-color has-text-color has-link-color has-large-font-size wp-elements-14\">Field Case: Why Moving Straight to 385 V Left the VFDs Exposed<\/h2>\n<\/blockquote>\n\n\n\n<p class=\"wp-block-paragraph\">An anonymized cold-chain packaging facility in Southeast Asia experienced repeated SPD disconnector operation on secondary 230\/400 V distribution panels during the first three months after commissioning. The indicators on several installed 275 V Type 2 cartridges changed to red. The local contractor assumed that frequent lightning surges were exhausting the SPDs and replaced the cartridges with 385 V versions, treating the higher U<sub>c<\/sub> as a heavier-duty rating.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Two months later, a grid-switching event was followed by dielectric failure in three variable frequency drives and two digital controller cards. The 385 V cartridges remained serviceable, forcing the investigation to separate the original nuisance disconnection from the later failure of protection coordination.<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"341\" src=\"https:\/\/jutrion.com\/wp-content\/uploads\/2026\/10\/04-385v-spd-vfd-field-case-1024x341.webp\" alt=\"\" class=\"wp-image-2233\" srcset=\"https:\/\/jutrion.com\/wp-content\/uploads\/2026\/10\/04-385v-spd-vfd-field-case-1024x341.webp 1024w, https:\/\/jutrion.com\/wp-content\/uploads\/2026\/10\/04-385v-spd-vfd-field-case-300x100.webp 300w, https:\/\/jutrion.com\/wp-content\/uploads\/2026\/10\/04-385v-spd-vfd-field-case-768x256.webp 768w, https:\/\/jutrion.com\/wp-content\/uploads\/2026\/10\/04-385v-spd-vfd-field-case-18x6.webp 18w, https:\/\/jutrion.com\/wp-content\/uploads\/2026\/10\/04-385v-spd-vfd-field-case.webp 1200w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\"><code><em>Field case showing a 385 V SPD, 60 cm connection path and approximately 2.4 kV reaching downstream VFDs.<\/em><\/code><\/figcaption><\/figure>\n\n\n\n<h3 class=\"wp-block-heading has-palette-color-9-color has-text-color has-link-color has-medium-font-size wp-elements-15\">Why the 275 V Cartridges Were Disconnecting<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Recorded phase-to-neutral voltage repeatedly reached 258\u2013262 V AC RMS and contained notable fifth-harmonic distortion. The investigation attributed rising varistor leakage and temperature to prolonged power-frequency stress rather than repeated lightning impulses. This does not mean every 275 V SPD will fail at 262 V: the response also depends on TOV data, waveform, ambient temperature and ageing. Here, the site measurements and product data had not been reviewed together.<\/p>\n\n\n\n<h3 class=\"wp-block-heading has-palette-color-9-color has-text-color has-link-color has-medium-font-size wp-elements-16\">Why the 385 V Replacement Was Not an Equivalent Upgrade<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">The 385 V cartridges tolerated the elevated supply, but their declared U<sub>p<\/sub> was 1.8 kV versus no more than 1.35 kV for the original cartridges. The 60 cm connection path was estimated, for the assessed surge current and geometry, to add about 0.6 kV. The resulting 2.4 kV first-pass estimate did not exceed the drives\u2019 stated 2.5 kV impulse withstand, but it left almost no margin for tolerance, waveform and installation effects.<\/p>\n\n\n\n<h3 class=\"wp-block-heading has-palette-color-9-color has-text-color has-link-color has-medium-font-size wp-elements-17\">Resolution: Use the Middle Voltage Class and Shorten the Current Path<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">The replacement used a JUTRION 320 V Type 2 configuration declared at U<sub>p<\/sub> \u2264 1.4 kV. Its U<sub>c<\/sub> provided approximately 22% margin over the recorded 262 V RMS, subject to confirmation against the product documentation and site TOV assessment. Busbar comb connections and optimized V-wiring reduced the total path from about 60 cm to less than 25 cm; under the same estimation method, inductive addition fell below approximately 0.25 kV and the effective protection estimate stayed below about 1.65 kV.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">No repeat nuisance disconnection or related controller damage was reported during the observation period. The correction combined sufficient continuous-voltage margin, a lower U<sub>p<\/sub> and a shorter discharge path instead of automatically selecting the highest U<sub>c<\/sub>.<\/p>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<h2 class=\"wp-block-heading has-palette-color-9-color has-text-color has-link-color has-large-font-size wp-elements-18\">A Worked 230\/400 V Panel Comparison<\/h2>\n<\/blockquote>\n\n\n\n<p class=\"wp-block-paragraph\">For an illustrative 230\/400 V commercial board with separate N and PE conductors and a 3+1 SPD, review the candidates in this order:<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>Identify the mode voltage.<\/strong> Each phase module is connected L\u2013N, so it normally sees about 230 V, not 400 V.<\/li>\n\n\n\n<li><strong>Establish the highest continuous supply voltage.<\/strong> Use the project\u2019s supply tolerance and any verified site data. Do not treat an abnormal neutral condition as an ordinary continuous operating point.<\/li>\n\n\n\n<li><strong>Define TOV duty.<\/strong> Review the earthing system, plausible neutral and earth faults, and the U<sub>T<\/sub>-versus-time data required by the installation design.<\/li>\n\n\n\n<li><strong>Compare approved products.<\/strong> A 275 V version may provide adequate continuous and TOV performance. If it does not, the 320 V version may be evaluated. A 385 V version remains a candidate only if the higher margin is actually necessary.<\/li>\n\n\n\n<li><strong>Recheck protection performance.<\/strong> Compare U<sub>p<\/sub> for each exact model, then include the effect of the connecting conductors and coordination with downstream protection.<\/li>\n<\/ol>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"341\" src=\"https:\/\/jutrion.com\/wp-content\/uploads\/2026\/10\/05-spd-lead-length-v-wiring-comparison-1024x341.webp\" alt=\"\" class=\"wp-image-2234\" srcset=\"https:\/\/jutrion.com\/wp-content\/uploads\/2026\/10\/05-spd-lead-length-v-wiring-comparison-1024x341.webp 1024w, https:\/\/jutrion.com\/wp-content\/uploads\/2026\/10\/05-spd-lead-length-v-wiring-comparison-300x100.webp 300w, https:\/\/jutrion.com\/wp-content\/uploads\/2026\/10\/05-spd-lead-length-v-wiring-comparison-768x256.webp 768w, https:\/\/jutrion.com\/wp-content\/uploads\/2026\/10\/05-spd-lead-length-v-wiring-comparison-18x6.webp 18w, https:\/\/jutrion.com\/wp-content\/uploads\/2026\/10\/05-spd-lead-length-v-wiring-comparison.webp 1200w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\"><code><em>Comparison of a 60 cm SPD connection and optimized V-wiring under 25 cm for improved VFD protection.<\/em><\/code><\/figcaption><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">If 275 V passes the continuous-voltage and TOV checks, it normally remains the first candidate. Move to 320 V when additional margin is required and U<sub>p<\/sub> remains acceptable. Use 385 V only when the mode or TOV duty justifies it and the downstream protection calculation still passes.<\/p>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<h2 class=\"wp-block-heading has-palette-color-9-color has-text-color has-link-color has-large-font-size wp-elements-19\">Read U<sub>c<\/sub>, la U<sub>T<\/sub> and U<sub>p<\/sub> as One Set<\/h2>\n<\/blockquote>\n\n\n\n<p class=\"wp-block-paragraph\">An SPD datasheet should allow the designer to trace three different voltage questions:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>U<sub>c<\/sub>:<\/strong> What voltage may remain continuously across this protection mode?<\/li>\n\n\n\n<li><strong>U<sub>T<\/sub> or TOV characteristic:<\/strong> What happens at a stated power-frequency overvoltage and duration\u2014does the SPD withstand it or fail safely?<\/li>\n\n\n\n<li><strong>U<sub>p<\/sub>:<\/strong> To what declared level does the SPD limit a specified impulse at its terminals?<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">Do not infer one value from another. After voltage compatibility is established, separately verify Type 1, Type 2 or Type 1+2 duty; I<sub>imp<\/sub>, I<sub>n<\/sub> et I<sub>max<\/sub>; prospective short-circuit current; disconnection; backup protection; and remote indication.<\/p>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<h2 class=\"wp-block-heading has-palette-color-9-color has-text-color has-link-color has-large-font-size wp-elements-20\">What to Put in an SPD Enquiry or Specification<\/h2>\n<\/blockquote>\n\n\n\n<p class=\"wp-block-paragraph\">\u201cNeed 4P 385 V SPD\u201d is not enough information for a reliable product match. Send the electrical context that determines the cartridge duty:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>nominal system voltage and frequency;<\/li>\n\n\n\n<li>single-phase or three-phase conductor arrangement;<\/li>\n\n\n\n<li>earthing system: TN-C, TN-S, TT, IT or another defined arrangement;<\/li>\n\n\n\n<li>required protection circuit, such as 1+1, 3+1 or 4+0;<\/li>\n\n\n\n<li>SPD type and installation position;<\/li>\n\n\n\n<li>required U<sub>c<\/sub>, TOV and U<sub>p<\/sub> performance;<\/li>\n\n\n\n<li>I<sub>imp<\/sub>, I<sub>n<\/sub> et I<sub>max<\/sub> requirements;<\/li>\n\n\n\n<li>prospective short-circuit current and upstream protection;<\/li>\n\n\n\n<li>remote contact, replaceable module and certification requirements; and<\/li>\n\n\n\n<li>destination market, quantity and project documentation needs.<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">La <a href=\"https:\/\/jutrion.com\/fr\/spd\/\">JUTRION AC SPD range<\/a> includes Type 2 and Type 1+2 options for low-voltage distribution systems. A final model should be matched to the actual network and connection diagram rather than selected from the U<sub>c<\/sub> number in isolation.<\/p>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<h2 class=\"wp-block-heading has-palette-color-9-color has-text-color has-link-color has-large-font-size wp-elements-21\">Common Questions About 275 V, 320 V and 385 V SPDs<\/h2>\n<\/blockquote>\n\n\n<div id=\"rank-math-faq\" class=\"rank-math-block\">\n<div class=\"rank-math-list\">\n<div id=\"faq-question-1791463372687\" class=\"rank-math-list-item\">\n<h3 class=\"rank-math-question\">Can I use a 385 V SPD on a 230 V system?<\/h3>\n<div class=\"rank-math-answer\">\n\n<p>Possibly, but it is not automatically the best choice. Confirm that the product is declared for the network and protection mode, then compare its U<sub>p<\/sub> with the protected equipment. The extra U<sub>c<\/sub> margin is useful only if the design needs it and the resulting protection level remains acceptable.<\/p>\n\n<\/div>\n<\/div>\n<div id=\"faq-question-1791464255661\" class=\"rank-math-list-item\">\n<h3 class=\"rank-math-question\">Is a 275 V SPD always correct for a 230 V supply?<\/h3>\n<div class=\"rank-math-answer\">\n\n<p>No. It is a common candidate for a mode that normally sees 230 V, but suitability depends on maximum continuous voltage, earthing system, TOV exposure, circuit arrangement and the exact datasheet.<\/p>\n\n<\/div>\n<\/div>\n<div id=\"faq-question-1791464321354\" class=\"rank-math-list-item\">\n<h3 class=\"rank-math-question\">Why would an SPD fail when no lightning strike was reported?<\/h3>\n<div class=\"rank-math-answer\">\n\n<p>Possible causes include repeated switching surges, sustained overvoltage, a lost or unstable neutral, incorrect U<sub>c<\/sub>, wrong protection circuit, ageing, loose connections or inadequate backup coordination. A failed indicator is a reason to investigate the system, not merely to fit a higher-voltage cartridge.<\/p>\n\n<\/div>\n<\/div>\n<div id=\"faq-question-1791464332925\" class=\"rank-math-list-item\">\n<h3 class=\"rank-math-question\">Does 320 V U<sub>c<\/sub> mean a 320 V nominal system?<\/h3>\n<div class=\"rank-math-answer\">\n\n<p>No. U<sub>c<\/sub> is the maximum continuous voltage across the SPD protection mode, not necessarily the nominal line-to-line or line-to-neutral system designation. Read it with the connection diagram.<\/p>\n\n<\/div>\n<\/div>\n<div id=\"faq-question-1791464348648\" class=\"rank-math-list-item\">\n<h3 class=\"rank-math-question\">Are U<sub>c<\/sub> and U<sub>CPV<\/sub> interchangeable?<\/h3>\n<div class=\"rank-math-answer\">\n\n<p>No. U<sub>CPV<\/sub> is used for photovoltaic DC SPD applications and must be selected from the maximum PV string voltage under the project\u2019s temperature conditions. For that task, use the separate <a href=\"https:\/\/jutrion.com\/fr\/how-to-select-dc-spd-solar-pv\/\">DC SPD selection guide for solar PV<\/a>.<\/p>\n\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<h2 class=\"wp-block-heading has-palette-color-9-color has-text-color has-link-color has-large-font-size wp-elements-22\">The Practical Selection Rule<\/h2>\n<\/blockquote>\n\n\n\n<p class=\"wp-block-paragraph\">Do not choose 275 V, 320 V or 385 V from the front label of the distribution board. First establish the voltage across each SPD protection mode, then verify the highest continuous voltage, earthing arrangement and TOV duty. From the ratings that pass those checks, choose the option that still gives adequate U<sub>p<\/sub> coordination at the protected equipment.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">In many ordinary 230 V protection modes, that process begins with 275 V. It moves to 320 V or 385 V only when the network conditions and manufacturer data support the change. Higher U<sub>c<\/sub> is additional voltage margin\u2014not a universal measure of better surge protection.<\/p>\n\n\n\n<h3 class=\"wp-block-heading has-palette-color-9-color has-text-color has-link-color has-medium-font-size wp-elements-23\">R\u00e9f\u00e9rences techniques<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li><a href=\"https:\/\/webstore.iec.ch\/en\/publication\/65314\" target=\"_blank\" rel=\"noopener\">IEC 61643-11:2025 \u2014 Low-voltage surge protective devices connected to AC low-voltage power systems<\/a><\/li>\n\n\n\n<li><a href=\"https:\/\/webstore.iec.ch\/en\/publication\/32531\" target=\"_blank\" rel=\"noopener\">IEC 61643-12:2020 \u2014 Selection and application principles for low-voltage SPDs<\/a><\/li>\n\n\n\n<li><a href=\"https:\/\/www.se.com\/ar\/es\/faqs\/FAQ000246782\/\" target=\"_blank\" rel=\"noopener\">Schneider Electric \u2014 IEC SPD parameters including U<sub>c<\/sub>, la U<sub>p<\/sub> et I<sub>n<\/sub><\/a><\/li>\n<\/ul>","protected":false},"excerpt":{"rendered":"<p>275 V, 320 V or 385 V: The Short Answer For a 230\/400 V AC installation, a 275 V SPD is often the first candidate when its protection mode normally sees about 230 V, but it is not an automatic choice for every network. Use 320 V when the approved design needs more continuous-voltage or [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":2236,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-2209","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-electrical-guides"],"blocksy_meta":[],"_links":{"self":[{"href":"https:\/\/jutrion.com\/fr\/wp-json\/wp\/v2\/posts\/2209","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/jutrion.com\/fr\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/jutrion.com\/fr\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/jutrion.com\/fr\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/jutrion.com\/fr\/wp-json\/wp\/v2\/comments?post=2209"}],"version-history":[{"count":1,"href":"https:\/\/jutrion.com\/fr\/wp-json\/wp\/v2\/posts\/2209\/revisions"}],"predecessor-version":[{"id":2237,"href":"https:\/\/jutrion.com\/fr\/wp-json\/wp\/v2\/posts\/2209\/revisions\/2237"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/jutrion.com\/fr\/wp-json\/wp\/v2\/media\/2236"}],"wp:attachment":[{"href":"https:\/\/jutrion.com\/fr\/wp-json\/wp\/v2\/media?parent=2209"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/jutrion.com\/fr\/wp-json\/wp\/v2\/categories?post=2209"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/jutrion.com\/fr\/wp-json\/wp\/v2\/tags?post=2209"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}