{"id":36488,"date":"2023-01-04T17:58:18","date_gmt":"2023-01-04T16:58:18","guid":{"rendered":"https:\/\/www.gt-engineering.it\/?post_type=normativa_tecnica&#038;p=36488"},"modified":"2023-07-10T11:07:24","modified_gmt":"2023-07-10T10:07:24","slug":"les-parametres-cles","status":"publish","type":"normativa_tecnica","link":"https:\/\/www.gt-engineering.it\/fr\/reglements-techniques\/normes-iec\/iec-62061-securite-fonctionnelle-des-machines\/les-parametres-cles\/","title":{"rendered":"Les param\u00e8tres cl\u00e9s"},"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                    <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\/01\/parameters-150x150.jpg\"\r\n                                type=\"image\/jpeg\"\r\n                            \/>\r\n                                                                                <source\r\n                                media=\"(max-width: 300px)\"\r\n                                width=\"300\"\r\n                                height=\"200\"\r\n                                srcset=\"https:\/\/www.gt-engineering.it\/wp-content\/uploads\/2023\/01\/parameters-300x200.jpg\"\r\n                                type=\"image\/jpeg\"\r\n                            \/>\r\n                                                                                <source\r\n                                media=\"(max-width: 768px)\"\r\n                                width=\"768\"\r\n                                height=\"513\"\r\n                                srcset=\"https:\/\/www.gt-engineering.it\/wp-content\/uploads\/2023\/01\/parameters-768x513.jpg\"\r\n                                type=\"image\/jpeg\"\r\n                            \/>\r\n                                                                                <source\r\n                                media=\"(max-width: 1024px)\"\r\n                                width=\"1024\"\r\n                                height=\"683\"\r\n                                srcset=\"https:\/\/www.gt-engineering.it\/wp-content\/uploads\/2023\/01\/parameters-1024x683.jpg\"\r\n                                type=\"image\/jpeg\"\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\/01\/parameters-scaled.jpg\"\r\n                                                        title=\"parameters\"\r\n                                                        type=\"image\/jpeg\"\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>La IEC 62061 utilise les principaux param\u00e8tres suivants.<\/p>\n<ul>\n<li><strong>\u03bb :<\/strong> Taux de d\u00e9faillance<\/li>\n<li><strong>MTTF<\/strong> : temps moyen avant d\u00e9faillance<\/li>\n<li><strong>SFF<\/strong> : Fraction de d\u00e9faillance s\u00fbre<\/li>\n<li><strong>HFT<\/strong> : Tol\u00e9rance aux pannes mat\u00e9rielles<\/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=\"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                    Taux de d\u00e9faillance    <\/h2>\n        <\/div>\n    \n<div class=\"a-text font-text text-base normal mt-8 first:mt-0 space-y-4\">\n    <p>Elle est \u00e0 la base de la IEC 61508 et donc de la IEC 62061. Nous pouvons emprunter sa d\u00e9finition \u00e0 la IEC 61508-4 :<\/p>\n<blockquote><p><em><strong>3.6.16 taux de d\u00e9faillance.<\/strong> Param\u00e8tre de fiabilit\u00e9 (\u03bb(t)) d&rsquo;une entit\u00e9 (composants individuels ou syst\u00e8mes) tel que \u03bb(t)-dt est la probabilit\u00e9 de d\u00e9faillance de cette entit\u00e9 dans [t, t+dt] \u00e0 condition qu&rsquo;elle ne soit pas tomb\u00e9e en panne pendant [0, t]<\/em><\/p><\/blockquote>\n<p>Math\u00e9matiquement, \u03bb(t) est la probabilit\u00e9 conditionnelle de d\u00e9faillance par unit\u00e9 de temps sur [t, t+dt].<\/p>\n<p>Elle est \u00e9troitement li\u00e9e \u00e0 la fonction de fiabilit\u00e9 :<\/p>\n<p>&nbsp;<\/p>\n<\/div>                <\/div>\n            <\/div>\n        \n                    <div\n                class=\"h-auto order-2   mt-6 md:mt-4 lg:mt-8 xl:mt-9 overflow-hidden shadow-content-image w-full md:w-1\/4\"\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=\"81\"\r\n                                srcset=\"https:\/\/www.gt-engineering.it\/wp-content\/uploads\/2023\/01\/Capture-150x81.png.webp\"\r\n                                type=\"image\/webp\"\r\n                            \/>\r\n                                                                                <source\r\n                                media=\"(max-width: 263px)\"\r\n                                width=\"263\"\r\n                                height=\"81\"\r\n                                srcset=\"https:\/\/www.gt-engineering.it\/wp-content\/uploads\/2023\/01\/Capture.png.webp\"\r\n                                type=\"image\/webp\"\r\n                            \/>\r\n                                                                                <source\r\n                                media=\"(max-width: 263px)\"\r\n                                width=\"263\"\r\n                                height=\"81\"\r\n                                srcset=\"https:\/\/www.gt-engineering.it\/wp-content\/uploads\/2023\/01\/Capture.png.webp\"\r\n                                type=\"image\/webp\"\r\n                            \/>\r\n                                                                                <source\r\n                                media=\"(max-width: 263px)\"\r\n                                width=\"263\"\r\n                                height=\"81\"\r\n                                srcset=\"https:\/\/www.gt-engineering.it\/wp-content\/uploads\/2023\/01\/Capture.png.webp\"\r\n                                type=\"image\/webp\"\r\n                            \/>\r\n                                                                            <img\r\n                            class=\"a-image transparent border-image h-auto  w-full mx-auto\"\r\n                                                        srcset=\"https:\/\/www.gt-engineering.it\/wp-content\/uploads\/2023\/01\/Capture.png.webp\"\r\n                                                        title=\"Capture\"\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>\n        <\/section>\n\n    \n\n\n\n\n    \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        \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>Pour utiliser la norme IEC 62061, chaque composant utilis\u00e9 dans le SCS doit avoir une valeur de taux de d\u00e9faillance. En cas de faible demande, c&rsquo;est normalement le cas. En cas de forte demande, le manque de donn\u00e9es directes a contribu\u00e9 \u00e0 l&rsquo;utilisation limit\u00e9e de la norme jusqu&rsquo;\u00e0 pr\u00e9sent.<\/p>\n<p>Les d\u00e9faillances peuvent \u00eatre divis\u00e9es en 4 parties :<\/p>\n<blockquote><p><em>\u03bbS : taux de d\u00e9faillances s\u00fbres<\/em><\/p>\n<p><em>\u03bbD : taux de d\u00e9faillances dangereuses (\u03bb x proportion de d\u00e9faillances dangereuses)<\/em><\/p>\n<p><em>\u03bbDD : taux de d\u00e9faillances dangereuses d\u00e9tect\u00e9es par les fonctions de diagnostic<\/em><\/p>\n<p><em>\u03bbDU : taux de d\u00e9faillances dangereuses NON d\u00e9tect\u00e9es par les fonctions de diagnostic<\/em><\/p>\n<p><em>\u01a9 \u03bbS + \u01a9 \u03bbD est le taux de d\u00e9faillance global.<\/em><\/p><\/blockquote>\n<p>Dans le cas d&rsquo;une demande \u00e9lev\u00e9e, seules les d\u00e9faillances dangereuses sont prises en compte. La partie d\u00e9tectable est calcul\u00e9e comme <strong>\u03bbDD=DC<\/strong> <strong>\u03bbD<\/strong> tandis que la partie ind\u00e9tectable est calcul\u00e9e comme<strong> \u03bbDU=(1-DC) \u03bbD<\/strong><\/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                    MTTFd    <\/h2>\n        <\/div>\n                <\/div>\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>Le temps moyen de d\u00e9faillance (<strong>MTTFD<\/strong>) est un param\u00e8tre utilis\u00e9 pour les composants non r\u00e9parables.<\/p>\n<p>Il s&rsquo;agit du temps pr\u00e9vu lorsque 63,2 % des composants test\u00e9s ont subi une d\u00e9faillance dangereuse. Il s&rsquo;agit d&rsquo;un param\u00e8tre statistique : si le MTTFD d&rsquo;une \u00e9lectrovanne est de 30 ans, cela ne signifie pas qu&rsquo;elle est garantie pendant 30 ans. Cela signifie simplement que, si l&rsquo;on consid\u00e8re par exemple 100 vannes, 63 d&rsquo;entre elles sont tomb\u00e9es en panne au bout de 30 ans ; cependant, si vous achetez l&rsquo;une de ces 100 vannes, elle peut tomber en panne au bout d&rsquo;un mois.<\/p>\n<p>Le MTTFD, ainsi que le \u03bbD,<strong> ne sont valables que pour la dur\u00e9e de vie utile du composant,<\/strong> qui est normalement de 20 ans. Au-del\u00e0 de cette p\u00e9riode, les param\u00e8tres perdent de leur importance, car les taux de d\u00e9faillance ne peuvent plus \u00eatre consid\u00e9r\u00e9s comme constants. En d&rsquo;autres termes, si une vanne hydraulique a une MTTFD de 150 ans, elle ne peut \u00eatre utilis\u00e9e que pendant 20 ans pour des op\u00e9rations li\u00e9es \u00e0 la s\u00e9curit\u00e9. Pass\u00e9 ce d\u00e9lai, elle doit \u00eatre remplac\u00e9e.<\/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 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=\"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                    Safe Failure Function \u2013 SFF    <\/h2>\n        <\/div>\n    \n<div class=\"a-text font-text text-base normal mt-8 first:mt-0 space-y-4\">\n    <p>The Safe Failure Fraction(SFF) a \u00e9t\u00e9 introduite dans la norme IEC 61508 en tant que mesure utilis\u00e9e pour d\u00e9terminer la tol\u00e9rance minimale aux d\u00e9faillances mat\u00e9rielles (HFT) d&rsquo;un sous-syst\u00e8me de s\u00e9curit\u00e9. Ci-apr\u00e8s ses d\u00e9finitions :<\/p>\n<blockquote><p>[<em>IEC 62061] 3.2 Termes et d\u00e9finitions<\/em><br \/>\n<em>3.2.56\u00a0<strong>Safe Failure Fraction<\/strong>(SFF) : fraction du taux de d\u00e9faillance global d&rsquo;un sous-syst\u00e8me qui n&rsquo;entra\u00eene pas de d\u00e9faillance dangereuse.<\/em><\/p><\/blockquote>\n<p>A premi\u00e8re vue, la d\u00e9finition de la IEC 62061 ne semble pas correcte ; mais il faut consid\u00e9rer que les d\u00e9faillances dangereuses d\u00e9tectables, puisqu&rsquo;elles sont d\u00e9tectables, ne g\u00e9n\u00e8rent aucune situation dangereuse : c&rsquo;est le raisonnement qui sous-tend la d\u00e9finition. <strong>Le SFF est utilis\u00e9 \u00e0 la fois en mode de forte et de faible demande, avec la m\u00eame signification.<\/strong><\/p>\n<p>\u00c9tant donn\u00e9 que les d\u00e9faillances mat\u00e9rielles al\u00e9atoires de la norme IEC 61508 sont bas\u00e9es sur les diff\u00e9rents types de taux de d\u00e9faillance d&rsquo;un composant, la SFF est une indication du degr\u00e9 de \u00ab\u00a0transparence\u00a0\u00bb des d\u00e9faillances. En d&rsquo;autres termes, plus le pourcentage de d\u00e9faillances dangereuses non d\u00e9tect\u00e9es est faible, plus le SFF est \u00e9lev\u00e9.<\/p>\n<p>Voici comment il est calcul\u00e9 :<\/p>\n<\/div>                <\/div>\n            <\/div>\n        \n                    <div\n                class=\"h-auto order-2   mt-6 md:mt-4 lg:mt-8 xl:mt-9 overflow-hidden shadow-content-image w-full\"\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=\"69\"\r\n                                srcset=\"https:\/\/www.gt-engineering.it\/wp-content\/uploads\/2023\/01\/Capture-2-150x69.png.webp\"\r\n                                type=\"image\/webp\"\r\n                            \/>\r\n                                                                                <source\r\n                                media=\"(max-width: 159px)\"\r\n                                width=\"159\"\r\n                                height=\"69\"\r\n                                srcset=\"https:\/\/www.gt-engineering.it\/wp-content\/uploads\/2023\/01\/Capture-2.png.webp\"\r\n                                type=\"image\/webp\"\r\n                            \/>\r\n                                                                                <source\r\n                                media=\"(max-width: 159px)\"\r\n                                width=\"159\"\r\n                                height=\"69\"\r\n                                srcset=\"https:\/\/www.gt-engineering.it\/wp-content\/uploads\/2023\/01\/Capture-2.png.webp\"\r\n                                type=\"image\/webp\"\r\n                            \/>\r\n                                                                                <source\r\n                                media=\"(max-width: 159px)\"\r\n                                width=\"159\"\r\n                                height=\"69\"\r\n                                srcset=\"https:\/\/www.gt-engineering.it\/wp-content\/uploads\/2023\/01\/Capture-2.png.webp\"\r\n                                type=\"image\/webp\"\r\n                            \/>\r\n                                                                            <img\r\n                            class=\"a-image transparent border-image h-auto  w-full mx-auto\"\r\n                                                        srcset=\"https:\/\/www.gt-engineering.it\/wp-content\/uploads\/2023\/01\/Capture-2.png.webp\"\r\n                                                        title=\"Capture\"\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>\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        \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><strong>Le SFF est la proportion de d\u00e9faillances \u00ab\u00a0s\u00fbres\u00a0\u00bb par rapport \u00e0 l&rsquo;ensemble des d\u00e9faillances<\/strong>. Une d\u00e9faillance \u00ab\u00a0s\u00fbre\u00a0\u00bb est soit une d\u00e9faillance qui est s\u00fbre de par sa conception, <strong>soit une d\u00e9faillance dangereuse qui est imm\u00e9diatement d\u00e9tect\u00e9e et corrig\u00e9e.<\/strong> Les normes IEC d\u00e9finissent une d\u00e9faillance s\u00fbre comme une d\u00e9faillance qui n&rsquo;a pas le potentiel de mettre le SIS dans un \u00e9tat dangereux ou de non-fonctionnement. Une d\u00e9faillance dangereuse est une d\u00e9faillance qui peut emp\u00eacher le SIS d&rsquo;effectuer un SIF sp\u00e9cifique, mais lorsqu&rsquo;elle est d\u00e9tect\u00e9e peu apr\u00e8s son apparition, par exemple par des diagnostics en ligne, la d\u00e9faillance est consid\u00e9r\u00e9e comme \u00ab\u00a0s\u00fbre\u00a0\u00bb puisque les diagnostics peuvent ramener le syst\u00e8me \u00e0 un \u00e9tat s\u00fbr.<\/p>\n<p>De nombreux dispositifs de s\u00e9curit\u00e9 \u00e9lectroniques sont dot\u00e9s de diagnostics int\u00e9gr\u00e9s, de sorte que la plupart des d\u00e9faillances dangereuses deviennent des d\u00e9faillances dangereuses d\u00e9tectables, ce qui leur conf\u00e8re un SFF \u00e9lev\u00e9, souvent sup\u00e9rieur \u00e0 90 %. Les dispositifs de s\u00e9curit\u00e9 m\u00e9caniques, pour lesquels les diagnostics internes ne sont pas r\u00e9alisables, <strong>auront, en g\u00e9n\u00e9ral, une faible SFF.<\/strong><\/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                    Hardware Fault Tolerance \u2013 HFT    <\/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\/01\/Tabella-6-620611.png-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=\"181\"\r\n                                srcset=\"https:\/\/www.gt-engineering.it\/wp-content\/uploads\/2023\/01\/Tabella-6-620611.png-1-300x181.webp\"\r\n                                type=\"image\/webp\"\r\n                            \/>\r\n                                                                                <source\r\n                                media=\"(max-width: 768px)\"\r\n                                width=\"768\"\r\n                                height=\"465\"\r\n                                srcset=\"https:\/\/www.gt-engineering.it\/wp-content\/uploads\/2023\/01\/Tabella-6-620611.png-1-768x465.webp\"\r\n                                type=\"image\/webp\"\r\n                            \/>\r\n                                                                                <source\r\n                                media=\"(max-width: 1024px)\"\r\n                                width=\"1024\"\r\n                                height=\"619\"\r\n                                srcset=\"https:\/\/www.gt-engineering.it\/wp-content\/uploads\/2023\/01\/Tabella-6-620611.png-1-1024x619.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\/01\/Tabella-6-620611.png-1.webp\"\r\n                                                        title=\"Tabella-6-620611.png\"\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 concept de tol\u00e9rance aux pannes mat\u00e9rielles (HFT) est utilis\u00e9 dans la norme IEC 61508 pour indiquer<strong> la capacit\u00e9 d&rsquo;un sous-syst\u00e8me mat\u00e9riel \u00e0 continuer \u00e0 ex\u00e9cuter une fonction requise<\/strong> en pr\u00e9sence de pannes ou d&rsquo;erreurs. La HFT est donn\u00e9e sous forme de chiffre, o\u00f9 <strong>HFT = 0 signifie que s&rsquo;il y a un d\u00e9faut, la fonction <\/strong>(par exemple, mesurer la pression)<strong> est perdue<\/strong>. HFT = 1 signifie que si une voie tombe en panne, il existe une autre voie capable d&rsquo;ex\u00e9cuter la m\u00eame fonction, ou que le sous-syst\u00e8me peut tol\u00e9rer une panne et continuer \u00e0 fonctionner. Un sous-syst\u00e8me compos\u00e9 de trois canaux vot\u00e9s 2oo3 fonctionne tant que deux de ses trois canaux fonctionnent. Cela signifie que le sous-syst\u00e8me peut tol\u00e9rer la d\u00e9faillance d&rsquo;un canal et continuer \u00e0 fonctionner normalement. La tol\u00e9rance aux pannes mat\u00e9rielles du groupe vot\u00e9 2oo3 est donc HFT = 1.<br \/>\n<strong>Voyons maintenant sa d\u00e9finition :<\/strong><\/p>\n<blockquote><p><em>[IEC 62061] 3.2 Termes et d\u00e9finitions<\/em><br \/>\n<em>3.2.36 Tol\u00e9rance aux pannes mat\u00e9rielles (HFT). Propri\u00e9t\u00e9 d&rsquo;un sous-syst\u00e8me de perdre potentiellement la fonction de s\u00e9curit\u00e9 sur au moins N+1 d\u00e9faillances.<\/em><\/p><\/blockquote>\n<p>L&rsquo;architecture du syst\u00e8me de contr\u00f4le et la \u00ab\u00a0safe failure fraction\u00a0\u00bb (SFF) jouent un r\u00f4le important dans la norme EN 62061. Le niveau d&rsquo;int\u00e9grit\u00e9 de la s\u00e9curit\u00e9 du mat\u00e9riel qui peut \u00eatre revendiqu\u00e9 pour un sous-syst\u00e8me est limit\u00e9 non seulement par le PFHD, mais aussi par la tol\u00e9rance aux fautes du mat\u00e9riel et la \u00ab\u00a0safe failure fraction\u00a0\u00bb.<\/p>\n<p>La combinaison de ces deux \u00e9l\u00e9ments est d\u00e9finie dans la nouvelle \u00e9dition 2021 de la norme comme les <strong>contraintes architecturales<\/strong> et son r\u00e9sultat est le SIL maximum que le sous-syst\u00e8me de s\u00e9curit\u00e9 peut atteindre (autrefois appel\u00e9 Sil Claim ou SIL CL).<\/p>\n<p>Le tableau 6 de l&rsquo;\u00e9dition 2021 d\u00e9taille le SIL maximal qu&rsquo;un composant peut atteindre, sur la base de sa fraction de d\u00e9faillance s\u00fbre et de son HFT. Comme on peut le voir, si un sous-syst\u00e8me 1oo1 (architecture de base du sous-syst\u00e8me A ou<strong> HFT=0<\/strong>) a un tr\u00e8s faible pourcentage de d\u00e9faillances dangereuses non d\u00e9tect\u00e9es (ce qui signifie un SFF \u00e9lev\u00e9), son sous-syst\u00e8me peut atteindre SIL 2 ou m\u00eame SIL3.<strong> La nouvelle \u00e9dition pr\u00e9cise que, dans le cas des composants \u00e9lectrom\u00e9caniques, cela est tr\u00e8s improbable.<\/strong><\/p>\n<\/div>            <\/div>\n        \n        \n                <div class=\"clear-both\"><\/div>\n        \n\n    <\/div>\n        <\/section>\n\n    \n","protected":false},"excerpt":{"rendered":"<p>IEC 62061 utilises les param\u00e8tres cl\u00e9s suivants :<\/p>\n","protected":false},"author":182,"featured_media":35559,"parent":36437,"menu_order":2,"template":"","meta":{"_acf_changed":false,"footnotes":""},"normative-tecniche":[165],"class_list":["post-36488","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 v27.7 - 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