{"id":37347,"date":"2023-01-04T17:57:58","date_gmt":"2023-01-04T16:57:58","guid":{"rendered":"https:\/\/www.gt-engineering.it\/?post_type=normativa_tecnica&#038;p=37347"},"modified":"2023-07-10T11:15:05","modified_gmt":"2023-07-10T10:15:05","slug":"systemes-it-les-bases","status":"publish","type":"normativa_tecnica","link":"https:\/\/www.gt-engineering.it\/fr\/reglements-techniques\/normes-iec\/iec-60364-4-41-protection-contre-les-chocs-elec\/systemes-it-les-bases\/","title":{"rendered":"Syst\u00e8mes IT : les bases"},"content":{"rendered":"\n\n    \n        <section\n            data-name=\"Contenuto testuale con immagine\"\n            class=\"bow-gte-testo-media u-spacer-base\"\n            id=\"\"\n        >\n            \n<div class=\"o-text-media px-side-spacer sm:px-side-spacer-sm lg:px-side-spacer-tablet 2xl:px-side-spacer-desktop flex flex-wrap items-start md:block\">\n\n    \n        \n        \n                    <div class=\"relative w-full\">\n                \n<div class=\"a-text font-text text-base normal mt-8 first:mt-0 space-y-4\">\n    <p>Dans les syst\u00e8mes IT, le<strong> neutre<\/strong> du transformateur de distribution<strong> n&rsquo;est pas mis \u00e0 la terre.<\/strong><\/p>\n<p>Ce syst\u00e8me \u00e9lectrique est utilis\u00e9 lorsque la coupure de l&rsquo;alimentation, en cas de d\u00e9faut, g\u00e9n\u00e8re plus de risques que la conservation de l&rsquo;\u00e9nergie. Par exemple, dans une salle d&rsquo;op\u00e9ration d&rsquo;un h\u00f4pital, supposons que pendant que le m\u00e9decin est en train d&rsquo;op\u00e9rer, un \u00e9quipement \u00e9lectrique soit d\u00e9fectueux ; la d\u00e9connexion de l&rsquo;alimentation aura des cons\u00e9quences bien pires que le maintien de l&rsquo;\u00e9nergie \u00e9lectrique dans la salle.<\/p>\n<p>La raison pour laquelle le neutre n&rsquo;est pas mis \u00e0 la terre est pr\u00e9cis\u00e9ment d&#8217;emp\u00eacher le courant de circuler \u00e0 travers le corps humain au cas o\u00f9 il toucherait l&rsquo;\u00e9quipement d\u00e9fectueux. Dans le cas d&rsquo;un syst\u00e8me TT ou TN, une personne peut \u00eatre \u00e9lectrocut\u00e9e parce que le courant, qui circule dans son corps,<strong> revient \u00e0 la source : le neutre mis \u00e0 la terre du transformateur MT\/BT<\/strong>. Si le point neutre n&rsquo;est pas mis \u00e0 la terre, il n&rsquo;y a pas de retour \u00e0 la source !<\/p>\n<p>Pour cette raison, la norme permet de ne pas couper l&rsquo;\u00e9nergie,<strong> mais le d\u00e9faut doit \u00eatre mis en \u00e9vidence<\/strong> car les gens doivent se rendre compte qu&rsquo;ils travaillent dans un environnement o\u00f9 un d\u00e9faut \u00e9lectrique est pr\u00e9sent. Ci-apr\u00e8s, le langage de la norme :<\/p>\n<blockquote><p><em>[IEC 60364-4-41] 411.6.3 Dans les syst\u00e8mes IT, les dispositifs de surveillance et de protection suivants peuvent \u00eatre utilis\u00e9s :<\/em><\/p><\/blockquote>\n<ul>\n<li>\n<blockquote><p><em>dispositifs de contr\u00f4le de l&rsquo;isolement (IMD)<\/em><\/p><\/blockquote>\n<\/li>\n<li>\n<blockquote><p><em>dispositifs de contr\u00f4le du courant r\u00e9siduel (RCM)<\/em><\/p><\/blockquote>\n<\/li>\n<li>\n<blockquote><p><em>syst\u00e8mes de localisation des d\u00e9fauts d&rsquo;isolement (IFLS) ;<\/em><\/p><\/blockquote>\n<\/li>\n<li>\n<blockquote><p><em>dispositifs de protection contre les surintensit\u00e9s ;<\/em><\/p><\/blockquote>\n<\/li>\n<li>\n<blockquote><p><em>dispositifs de protection \u00e0 courant diff\u00e9rentiel r\u00e9siduel (DDR).<\/em><\/p><\/blockquote>\n<\/li>\n<\/ul>\n<p>&nbsp;<\/p>\n<\/div>            <\/div>\n        \n        \n                <div class=\"clear-both\"><\/div>\n        \n\n    <\/div>\n        <\/section>\n\n    \n\n\n\n\n    \n        <section\n            data-name=\"Contenuto testuale con immagine\"\n            class=\"bow-gte-testo-media u-spacer-base\"\n            id=\"\"\n        >\n            \n<div class=\"o-text-media px-side-spacer sm:px-side-spacer-sm lg:px-side-spacer-tablet 2xl:px-side-spacer-desktop flex flex-wrap items-start md:block\">\n\n    \n        \n                    <div\n                class=\"h-auto mb-6 md:mb-4 lg:mb-8 xl:mb-9 float-left mr-6 md:mr-4 lg:mr-8 xl:mr-9  overflow-hidden shadow-content-image w-full md:w-1\/3\"\n            >\n                \r\n\r\n    \r\n        \r\n            \r\n                \r\n                    <picture\r\n                        class=\"\"\r\n                                            >\r\n                                                                                                        <source\r\n                                media=\"(max-width: 150px)\"\r\n                                width=\"150\"\r\n                                height=\"150\"\r\n                                srcset=\"https:\/\/www.gt-engineering.it\/wp-content\/uploads\/2023\/06\/Seconda-1-150x150.webp\"\r\n                                type=\"image\/webp\"\r\n                            \/>\r\n                                                                                <source\r\n                                media=\"(max-width: 300px)\"\r\n                                width=\"300\"\r\n                                height=\"176\"\r\n                                srcset=\"https:\/\/www.gt-engineering.it\/wp-content\/uploads\/2023\/06\/Seconda-1-300x176.webp\"\r\n                                type=\"image\/webp\"\r\n                            \/>\r\n                                                                                <source\r\n                                media=\"(max-width: 768px)\"\r\n                                width=\"768\"\r\n                                height=\"449\"\r\n                                srcset=\"https:\/\/www.gt-engineering.it\/wp-content\/uploads\/2023\/06\/Seconda-1-768x449.webp\"\r\n                                type=\"image\/webp\"\r\n                            \/>\r\n                                                                                <source\r\n                                media=\"(max-width: 1024px)\"\r\n                                width=\"1024\"\r\n                                height=\"599\"\r\n                                srcset=\"https:\/\/www.gt-engineering.it\/wp-content\/uploads\/2023\/06\/Seconda-1-1024x599.webp\"\r\n                                type=\"image\/webp\"\r\n                            \/>\r\n                                                                            <img\r\n                            class=\"a-image transparent border-image h-auto  w-full\"\r\n                                                        srcset=\"https:\/\/www.gt-engineering.it\/wp-content\/uploads\/2023\/06\/Seconda-1.webp\"\r\n                                                        title=\"Seconda-1\"\r\n                                                        type=\"image\/webp\"\r\n                        \/>\r\n                    <\/picture>\r\n\r\n                \r\n\r\n                    \r\n    \r\n            <\/div>\n        \n                    <div class=\"relative w-full\">\n                \n<div class=\"a-text font-text text-base normal mt-8 first:mt-0 space-y-4\">\n    <p>On peut se demander pourquoi la norme s&rsquo;inqui\u00e8te d&rsquo;un d\u00e9faut apparemment inoffensif. <strong>La raison en est l&rsquo;augmentation du risque en cas de second d\u00e9faut sur une autre phase.<\/strong> Dans le cas d&rsquo;un syst\u00e8me triphas\u00e9, le premier d\u00e9faut peut se trouver sur la phase L2 et le second sur la phase L3. Dans cette situation, si une personne touche les deux \u00e9quipements d\u00e9fectueux, elle s&rsquo;expose \u00e0 un choc \u00e9lectrique de 400 Vca (en Europe).<\/p>\n<p>Comment \u00e9viter cela ? C&rsquo;est tr\u00e8s simple : toutes les parties conductrices expos\u00e9es doivent \u00eatre reli\u00e9es entre elles !<\/p>\n<\/div>            <\/div>\n        \n        \n                <div class=\"clear-both\"><\/div>\n        \n\n    <\/div>\n        <\/section>\n\n    \n\n\n\n\n    \n        <section\n            data-name=\"Contenuto testuale con immagine\"\n            class=\"bow-gte-testo-media u-spacer-base\"\n            id=\"\"\n        >\n            \n<div class=\"o-text-media px-side-spacer sm:px-side-spacer-sm lg:px-side-spacer-tablet 2xl:px-side-spacer-desktop flex flex-wrap items-start md:block\">\n\n    \n                    <div class=\"mb-6 relative w-full md:mb-4 lg:mb-8 xl:mb-9\">\n                \n        <div                class=\"m-headings\"\n            >\n    \n    \n<h2 class=\"a-heading text-left text-primary font-heading text-2xl lg:text-3xl xl:text-4xl font-normal mt-2 first:mt-0\">\n                    Syst\u00e8mes IT : comment la s\u00e9curit\u00e9 est-elle garantie ?    <\/h2>\n        <\/div>\n                <\/div>\n        \n                    <div\n                class=\"h-auto mb-6 md:mb-4 lg:mb-8 xl:mb-9 float-left mr-6 md:mr-4 lg:mr-8 xl:mr-9  overflow-hidden shadow-content-image w-full md:w-1\/3\"\n            >\n                \r\n\r\n    \r\n        \r\n            \r\n                \r\n                    <picture\r\n                        class=\"\"\r\n                                            >\r\n                                                                                                        <source\r\n                                media=\"(max-width: 150px)\"\r\n                                width=\"150\"\r\n                                height=\"150\"\r\n                                srcset=\"https:\/\/www.gt-engineering.it\/wp-content\/uploads\/2023\/06\/Terza-150x150.webp\"\r\n                                type=\"image\/webp\"\r\n                            \/>\r\n                                                                                <source\r\n                                media=\"(max-width: 300px)\"\r\n                                width=\"300\"\r\n                                height=\"150\"\r\n                                srcset=\"https:\/\/www.gt-engineering.it\/wp-content\/uploads\/2023\/06\/Terza-300x150.webp\"\r\n                                type=\"image\/webp\"\r\n                            \/>\r\n                                                                                <source\r\n                                media=\"(max-width: 768px)\"\r\n                                width=\"768\"\r\n                                height=\"385\"\r\n                                srcset=\"https:\/\/www.gt-engineering.it\/wp-content\/uploads\/2023\/06\/Terza-768x385.webp\"\r\n                                type=\"image\/webp\"\r\n                            \/>\r\n                                                                                <source\r\n                                media=\"(max-width: 1024px)\"\r\n                                width=\"1024\"\r\n                                height=\"513\"\r\n                                srcset=\"https:\/\/www.gt-engineering.it\/wp-content\/uploads\/2023\/06\/Terza-1024x513.webp\"\r\n                                type=\"image\/webp\"\r\n                            \/>\r\n                                                                            <img\r\n                            class=\"a-image transparent border-image h-auto  w-full\"\r\n                                                        srcset=\"https:\/\/www.gt-engineering.it\/wp-content\/uploads\/2023\/06\/Terza.webp\"\r\n                                                        title=\"Terza\"\r\n                                                        type=\"image\/webp\"\r\n                        \/>\r\n                    <\/picture>\r\n\r\n                \r\n\r\n                    \r\n    \r\n            <\/div>\n        \n                    <div class=\"relative w-full\">\n                \n<div class=\"a-text font-text text-base normal mt-8 first:mt-0 space-y-4\">\n    <p>Le dispositif de surveillance est la premi\u00e8re condition pour r\u00e9duire le risque. <strong>La deuxi\u00e8me condition est la liaison de toutes les parties conductrices expos\u00e9es<\/strong>. En effet, si elles sont toutes reli\u00e9es ensemble, en cas de premier d\u00e9faut sur, disons, L1, lorsque le second sur L3 se produit, ce dernier devient comme un court-circuit.<\/p>\n<p>Le courant de court-circuit d\u00e9clenche l&rsquo;ouverture de la protection contre les courts-circuits (disjoncteur par exemple) et donc l&rsquo;interruption de l&rsquo;\u00e9nergie vers l&rsquo;\u00e9quipement.<\/p>\n<\/div>            <\/div>\n        \n        \n                <div class=\"clear-both\"><\/div>\n        \n\n    <\/div>\n        <\/section>\n\n    \n\n\n\n\n    \n        <section\n            data-name=\"Contenuto testuale con immagine\"\n            class=\"bow-gte-testo-media u-spacer-base\"\n            id=\"\"\n        >\n            \n<div class=\"o-text-media px-side-spacer sm:px-side-spacer-sm lg:px-side-spacer-tablet 2xl:px-side-spacer-desktop flex flex-wrap items-start md:block\">\n\n    \n        \n                    <div\n                class=\"h-auto mb-6 md:mb-4 lg:mb-8 xl:mb-9 float-left mr-6 md:mr-4 lg:mr-8 xl:mr-9  overflow-hidden shadow-content-image w-full md:w-1\/3\"\n            >\n                \r\n\r\n    \r\n        \r\n            \r\n                \r\n                    <picture\r\n                        class=\"\"\r\n                                            >\r\n                                                                                                        <source\r\n                                media=\"(max-width: 150px)\"\r\n                                width=\"150\"\r\n                                height=\"150\"\r\n                                srcset=\"https:\/\/www.gt-engineering.it\/wp-content\/uploads\/2023\/06\/Quarta-150x150.webp\"\r\n                                type=\"image\/webp\"\r\n                            \/>\r\n                                                                                <source\r\n                                media=\"(max-width: 300px)\"\r\n                                width=\"300\"\r\n                                height=\"282\"\r\n                                srcset=\"https:\/\/www.gt-engineering.it\/wp-content\/uploads\/2023\/06\/Quarta-300x282.webp\"\r\n                                type=\"image\/webp\"\r\n                            \/>\r\n                                                                                <source\r\n                                media=\"(max-width: 768px)\"\r\n                                width=\"768\"\r\n                                height=\"721\"\r\n                                srcset=\"https:\/\/www.gt-engineering.it\/wp-content\/uploads\/2023\/06\/Quarta-768x721.webp\"\r\n                                type=\"image\/webp\"\r\n                            \/>\r\n                                                                                <source\r\n                                media=\"(max-width: 1024px)\"\r\n                                width=\"1024\"\r\n                                height=\"961\"\r\n                                srcset=\"https:\/\/www.gt-engineering.it\/wp-content\/uploads\/2023\/06\/Quarta-1024x961.webp\"\r\n                                type=\"image\/webp\"\r\n                            \/>\r\n                                                                            <img\r\n                            class=\"a-image transparent border-image h-auto  w-full\"\r\n                                                        srcset=\"https:\/\/www.gt-engineering.it\/wp-content\/uploads\/2023\/06\/Quarta.webp\"\r\n                                                        title=\"Quarta\"\r\n                                                        type=\"image\/webp\"\r\n                        \/>\r\n                    <\/picture>\r\n\r\n                \r\n\r\n                    \r\n    \r\n            <\/div>\n        \n                    <div class=\"relative w-full\">\n                \n<div class=\"a-text font-text text-base normal mt-8 first:mt-0 space-y-4\">\n    <p>Jusqu&rsquo;ici, tout va bien : les syst\u00e8mes IT sont s\u00fbrs parce que le point neutre n&rsquo;est pas mis \u00e0 la terre :<\/p>\n<ol>\n<li><strong>Le point neutre n&rsquo;est pas mis \u00e0 la terre<\/strong> et donc le courant qui traverse le corps qui touche un \u00e9quipement d\u00e9fectueux ne trouve pas le moyen de revenir \u00e0 la source : la personne est en s\u00e9curit\u00e9 !<\/li>\n<li>Dans tous les cas, <strong>le d\u00e9faut est d\u00e9tect\u00e9<\/strong>, par exemple, par un <strong>dispositif de surveillance de l&rsquo;isolation<\/strong>. L&rsquo;illustration montre un exemple de IMD : en l&rsquo;absence de d\u00e9faut, les trois lampes sont allum\u00e9es. En cas de d\u00e9faut \u00e0 la terre sur L2, la lampe du milieu s&rsquo;\u00e9teint. Il s&rsquo;agit bien s\u00fbr d&rsquo;une \u00ab\u00a0m\u00e9thode didactique\u00a0\u00bb, juste pour expliquer le concept.<\/li>\n<\/ol>\n<p><strong>Toutes les parties conductrices expos\u00e9es sont connect\u00e9es ensemble<\/strong> de sorte qu&rsquo;en cas de second d\u00e9faut sur une autre phase, une protection contre les courts-circuits ouvrira le circuit d\u00e9fectueux. Si le d\u00e9faut se produit sur la m\u00eame phase, la protection ne s&rsquo;ouvre pas, mais le d\u00e9faut n&rsquo;est pas dangereux pour les personnes.<\/p>\n<\/div>            <\/div>\n        \n        \n                <div class=\"clear-both\"><\/div>\n        \n\n    <\/div>\n        <\/section>\n\n    \n\n\n\n\n    \n        <section\n            data-name=\"Contenuto testuale con immagine\"\n            class=\"bow-gte-testo-media u-spacer-base\"\n            id=\"\"\n        >\n            \n<div class=\"o-text-media px-side-spacer sm:px-side-spacer-sm lg:px-side-spacer-tablet 2xl:px-side-spacer-desktop flex flex-wrap items-start md:block\">\n\n    \n                    <div class=\"mb-6 relative w-full md:mb-4 lg:mb-8 xl:mb-9\">\n                \n        <div                class=\"m-headings\"\n            >\n    \n    \n<h2 class=\"a-heading text-left text-primary font-heading text-2xl lg:text-3xl xl:text-4xl font-normal mt-2 first:mt-0\">\n                    Syst\u00e8mes IT : les courants parasites    <\/h2>\n        <\/div>\n                <\/div>\n        \n                    <div\n                class=\"h-auto mb-6 md:mb-4 lg:mb-8 xl:mb-9 float-left mr-6 md:mr-4 lg:mr-8 xl:mr-9  overflow-hidden shadow-content-image w-full md:w-1\/3\"\n            >\n                \r\n\r\n    \r\n        \r\n            \r\n                \r\n                    <picture\r\n                        class=\"\"\r\n                                            >\r\n                                                                                                        <source\r\n                                media=\"(max-width: 150px)\"\r\n                                width=\"150\"\r\n                                height=\"150\"\r\n                                srcset=\"https:\/\/www.gt-engineering.it\/wp-content\/uploads\/2023\/06\/Quinta-150x150.webp\"\r\n                                type=\"image\/webp\"\r\n                            \/>\r\n                                                                                <source\r\n                                media=\"(max-width: 300px)\"\r\n                                width=\"300\"\r\n                                height=\"173\"\r\n                                srcset=\"https:\/\/www.gt-engineering.it\/wp-content\/uploads\/2023\/06\/Quinta-300x173.webp\"\r\n                                type=\"image\/webp\"\r\n                            \/>\r\n                                                                                <source\r\n                                media=\"(max-width: 768px)\"\r\n                                width=\"768\"\r\n                                height=\"443\"\r\n                                srcset=\"https:\/\/www.gt-engineering.it\/wp-content\/uploads\/2023\/06\/Quinta-768x443.webp\"\r\n                                type=\"image\/webp\"\r\n                            \/>\r\n                                                                                <source\r\n                                media=\"(max-width: 1024px)\"\r\n                                width=\"1024\"\r\n                                height=\"590\"\r\n                                srcset=\"https:\/\/www.gt-engineering.it\/wp-content\/uploads\/2023\/06\/Quinta-1024x590.webp\"\r\n                                type=\"image\/webp\"\r\n                            \/>\r\n                                                                            <img\r\n                            class=\"a-image transparent border-image h-auto  w-full\"\r\n                                                        srcset=\"https:\/\/www.gt-engineering.it\/wp-content\/uploads\/2023\/06\/Quinta.webp\"\r\n                                                        title=\"Quinta\"\r\n                                                        type=\"image\/webp\"\r\n                        \/>\r\n                    <\/picture>\r\n\r\n                \r\n\r\n                    \r\n    \r\n            <\/div>\n        \n                    <div class=\"relative w-full\">\n                \n<div class=\"a-text font-text text-base normal mt-8 first:mt-0 space-y-4\">\n    <p>Jusqu&rsquo;\u00e0 pr\u00e9sent, tout va bien, mais il manque un aspect important dans les syst\u00e8mes IT : <strong>les courants parasites<\/strong>.<\/p>\n<p>Si le neutre n&rsquo;est pas mis \u00e0 la terre,<strong> il n&rsquo;y a pas de retour \u00e0 la source<\/strong> et la personne est en s\u00e9curit\u00e9. En r\u00e9alit\u00e9, malheureusement, m\u00eame dans un syst\u00e8me non reli\u00e9 \u00e0 la terre,<strong> le courant trouve un moyen de retourner \u00e0 la source<\/strong> ! Le probl\u00e8me est qu&rsquo;un syst\u00e8me IT peut s&rsquo;\u00e9tendre sur des kilom\u00e8tres et que plus le r\u00e9seau est grand, plus la capacit\u00e9 <strong>parasite est importante<\/strong>.<\/p>\n<p>Il existe des r\u00e8gles de base pour estimer les courants parasites : en voici une :<\/p>\n<p>Id = 0.4 s<\/p>\n<p>O\u00f9 :<\/p>\n<p>Id est le courant parasites en A et<br \/>\nS est la puissance install\u00e9e en MVA<br \/>\nPar exemple, si la distribution IT est compos\u00e9e d&rsquo;\u00e9quipements ayant une puissance install\u00e9e de 100 kVA, un courant parasites de 40 mA peut circuler \u00e0 travers la r\u00e9sistance de terre de l&rsquo;\u00e9quipement.<\/p>\n<p>La raison pour laquelle les courants parasites sont dangereux dans les syst\u00e8mes IT est<strong> qu&rsquo;ils peuvent cr\u00e9er des tensions de contact dangereuses<\/strong>.<\/p>\n<p>C&rsquo;est pourquoi le langage utilis\u00e9 pour limiter le risque li\u00e9 aux courants parasites dans les syst\u00e8mes IT est le suivant.<\/p>\n<blockquote><p><em>[IEC 60364-4-41] 411.6.2 Les pi\u00e8ces conductrices expos\u00e9es doivent \u00eatre mises \u00e0 la terre individuellement, en groupes ou collectivement. La condition suivante doit \u00eatre remplie : Dans les syst\u00e8mes \u00e0 courant alternatif, la condition suivante doit \u00eatre remplie pour limiter la tension de contact \u00e0 :<\/em><\/p><\/blockquote>\n<p>O\u00f9 :<\/p>\n<ul>\n<li><strong>Ra<\/strong> est la somme des r\u00e9sistances en \u03a9 de l&rsquo;\u00e9lectrode de terre et du conducteur de protection pour les parties conductrices expos\u00e9es ;<\/li>\n<li><strong>Id<\/strong> est le courant de d\u00e9faut en A du premier d\u00e9faut d&rsquo;imp\u00e9dance n\u00e9gligeable entre un conducteur de ligne et une partie conductrice expos\u00e9e. La valeur de Id tient compte des courants de fuite et de l&rsquo;imp\u00e9dance totale de mise \u00e0 la terre de l&rsquo;installation \u00e9lectrique.<\/li>\n<\/ul>\n<p>&nbsp;<\/p>\n<\/div>            <\/div>\n        \n        \n                <div class=\"clear-both\"><\/div>\n        \n\n    <\/div>\n        <\/section>\n\n    \n\n\n\n\n    \n        <section\n            data-name=\"Contenuto testuale con immagine\"\n            class=\"bow-gte-testo-media u-spacer-base\"\n            id=\"\"\n        >\n            \n<div class=\"o-text-media px-side-spacer sm:px-side-spacer-sm lg:px-side-spacer-tablet 2xl:px-side-spacer-desktop flex flex-wrap items-start md:block\">\n\n    \n        \n                    <div\n                class=\"h-auto mb-6 md:mb-4 lg:mb-8 xl:mb-9 float-left mr-6 md:mr-4 lg:mr-8 xl:mr-9  overflow-hidden shadow-content-image w-full md:w-1\/3\"\n            >\n                \r\n\r\n    \r\n        \r\n            \r\n                \r\n                    <picture\r\n                        class=\"\"\r\n                                            >\r\n                                                                                                        <source\r\n                                media=\"(max-width: 150px)\"\r\n                                width=\"150\"\r\n                                height=\"150\"\r\n                                srcset=\"https:\/\/www.gt-engineering.it\/wp-content\/uploads\/2023\/06\/Sesta-150x150.webp\"\r\n                                type=\"image\/webp\"\r\n                            \/>\r\n                                                                                <source\r\n                                media=\"(max-width: 300px)\"\r\n                                width=\"300\"\r\n                                height=\"173\"\r\n                                srcset=\"https:\/\/www.gt-engineering.it\/wp-content\/uploads\/2023\/06\/Sesta-300x173.webp\"\r\n                                type=\"image\/webp\"\r\n                            \/>\r\n                                                                                <source\r\n                                media=\"(max-width: 768px)\"\r\n                                width=\"768\"\r\n                                height=\"443\"\r\n                                srcset=\"https:\/\/www.gt-engineering.it\/wp-content\/uploads\/2023\/06\/Sesta-768x443.webp\"\r\n                                type=\"image\/webp\"\r\n                            \/>\r\n                                                                                <source\r\n                                media=\"(max-width: 1024px)\"\r\n                                width=\"1024\"\r\n                                height=\"590\"\r\n                                srcset=\"https:\/\/www.gt-engineering.it\/wp-content\/uploads\/2023\/06\/Sesta-1024x590.webp\"\r\n                                type=\"image\/webp\"\r\n                            \/>\r\n                                                                            <img\r\n                            class=\"a-image transparent border-image h-auto  w-full\"\r\n                                                        srcset=\"https:\/\/www.gt-engineering.it\/wp-content\/uploads\/2023\/06\/Sesta.webp\"\r\n                                                        title=\"Sesta\"\r\n                                                        type=\"image\/webp\"\r\n                        \/>\r\n                    <\/picture>\r\n\r\n                \r\n\r\n                    \r\n    \r\n            <\/div>\n        \n                    <div class=\"relative w-full\">\n                \n<div class=\"a-text font-text text-base normal mt-8 first:mt-0 space-y-4\">\n    <p>En d\u00e9finitive, pourquoi un syst\u00e8me IT est-il s\u00fbr ? Parce que quatre conditions doivent \u00eatre remplies :<\/p>\n<ul>\n<li><strong>Toutes les parties conductrices expos\u00e9es doivent \u00eatre reli\u00e9es entre elles<\/strong>.<\/li>\n<li><strong>Le premier d\u00e9faut est d\u00e9tect\u00e9<\/strong>, par exemple, par un<strong> dispositif de surveillance de l&rsquo;isolation<\/strong>.<\/li>\n<li>Le courant de d\u00e9faut <strong>ne doit pas g\u00e9n\u00e9rer une tension de contact dangereuse<\/strong> (\u2264 50 Vac).<\/li>\n<li><strong>Un deuxi\u00e8me d\u00e9faut sur une phase diff\u00e9rente doit \u00eatre d\u00e9tect\u00e9<\/strong> et un dispositif de courant de court-circuit doit mettre les appareils hors tension. Ci-apr\u00e8s la langue utilis\u00e9e dans la norme :<\/li>\n<\/ul>\n<\/div>            <\/div>\n        \n        \n                <div class=\"clear-both\"><\/div>\n        \n\n    <\/div>\n        <\/section>\n\n    \n\n\n\n\n    \n        <section\n            data-name=\"Contenuto testuale con immagine\"\n            class=\"bow-gte-testo-media u-spacer-base\"\n            id=\"\"\n        >\n            \n<div class=\"o-text-media px-side-spacer sm:px-side-spacer-sm lg:px-side-spacer-tablet 2xl:px-side-spacer-desktop flex flex-wrap items-start flex-col\">\n\n    \n\n                    <div \n                class=\"order-2 relative w-full\"\n            >\n                <div\n                    class=\"pt-6 space-y-6 w-full md:pt-0 md:space-y-4 lg:space-y-8 xl:space-y-9\"\n                >\n                    \n<div class=\"a-text font-text text-base normal mt-8 first:mt-0 space-y-4\">\n    <blockquote><p><em><span lang=\"EN-GB\">[IEC 60364-4-41] <\/span>411.6.4 Apr\u00e8s l&rsquo;apparition d&rsquo;un premier d\u00e9faut, les conditions de coupure automatique de l&rsquo;alimentation, en cas de second d\u00e9faut survenant sur un conducteur sous tension diff\u00e9rent, doivent \u00eatre les suivantes :<\/em><\/p>\n<p><em>a) Lorsque les parties conductrices expos\u00e9es sont reli\u00e9es par un conducteur de protection collectivement mis \u00e0 la terre sur le m\u00eame syst\u00e8me de mise \u00e0 la terre, les conditions similaires \u00e0 un syst\u00e8me TN s&rsquo;appliquent et les conditions suivantes doivent \u00eatre remplies lorsque le neutre est mis \u00e0 la terre sur le m\u00eame syst\u00e8me de mise \u00e0 la terre que le conducteur sous tension.<\/em><\/p>\n<p><em>Les conditions suivantes doivent \u00eatre remplies lorsque le conducteur neutre n&rsquo;est pas distribu\u00e9 dans les r\u00e9seaux \u00e0 courant alternatif [&#8230;] :<\/em><\/p><\/blockquote>\n<p>2 * Ia * Zs \u2264 U<\/p>\n<p>O\u00f9<\/p>\n<ul>\n<li>U est la tension alternative nominale en V entre les conducteurs de ligne (normalement 400 Vca en Europe) ;<\/li>\n<li>Zs est l&rsquo;imp\u00e9dance en \u03a9 de la boucle de d\u00e9faut comprenant le conducteur de ligne et le conducteur de protection du circuit ;<\/li>\n<li>Ia est le courant en A qui provoque le fonctionnement du dispositif de protection dans le temps requis au 411.3.2.2 pour les syst\u00e8mes TN ou au 411.3.2.3.<\/li>\n<\/ul>\n<p>La formule peut sembler \u00e9trange, pourquoi ? Si nous l&rsquo;\u00e9crivons diff\u00e9remment, elle deviendra plus claire :<\/p>\n<p>Ia \u2264 \u00bd * U\/Zs<\/p>\n<p>Le probl\u00e8me est que Zs n&rsquo;est pas un courant de boucle de d\u00e9faut normal, mais le courant de boucle de d\u00e9faut de 2 boucles de d\u00e9faut. La norme consid\u00e8re que \u00ab\u00a0chaque courant de boucle de d\u00e9faut\u00a0\u00bb correspond \u00e0 la moiti\u00e9 du courant traversant la boucle compl\u00e8te. En fait, <strong>c&rsquo;est une fa\u00e7on d&rsquo;\u00eatre conservateur<\/strong> !<\/p>\n<\/div>                <\/div>\n            <\/div>\n        \n        \n    <\/div>\n        <\/section>\n\n    \n","protected":false},"excerpt":{"rendered":"<p>Dans les syst\u00e8mes IT, le neutre du transformateur de distribution n&rsquo;est pas mis \u00e0 la terre.<\/p>\n","protected":false},"author":182,"featured_media":37348,"parent":37153,"menu_order":5,"template":"","meta":{"_acf_changed":false,"footnotes":""},"normative-tecniche":[165],"class_list":["post-37347","normativa_tecnica","type-normativa_tecnica","status-publish","has-post-thumbnail","hentry","tipologia_normativa-normes-iec"],"acf":{"sottotitolo":"","allegati":null},"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v27.2 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>Syst\u00e8mes IT : les bases - Gt-Engineering<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.gt-engineering.it\/fr\/reglements-techniques\/normes-iec\/iec-60364-4-41-protection-contre-les-chocs-elec\/systemes-it-les-bases\/\" \/>\n<meta property=\"og:locale\" content=\"fr_FR\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Syst\u00e8mes IT : les bases - 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