{"id":758,"date":"2023-12-19T20:49:46","date_gmt":"2023-12-19T12:49:46","guid":{"rendered":"https:\/\/www.britecelectric.com\/?post_type=blog&p=758"},"modified":"2024-09-05T16:35:18","modified_gmt":"2024-09-05T08:35:18","slug":"low-voltage-power-supply-systems","status":"publish","type":"blog","link":"https:\/\/www.britecelectric.com\/sv\/blog\/low-voltage-power-supply-systems\/","title":{"rendered":"L\u00e5gsp\u00e4nningsn\u00e4tverk"},"content":{"rendered":"IEC-terminologi<\/strong>\r\n\r\nInternational standard IEC 60364 distinguishes three families of earthing arrangements, using the two-letter codes TN, TT, and IT.\r\n\r\nThe first letter indicates the connection between earth and the power-supply equipment (generator or transformer):\r\n\r\n\u201cT\u201d \u2014 Direct connection of a point with earth\r\n\r\n\u201cI\u201d \u2014 No point is connected with earth, except perhaps via high impedance.\r\n\r\nThe second letter indicates the connection between earth or network and the electrical device being supplied:\r\n\r\n\u201cT\u201d \u2014 Earth connection is by a local direct connection to earth, usually via a ground rod.\r\n\r\n\u201cN\u201d \u2014 the earth connection is supplied by the electricity supply network, either separately to the neutral conductor (TN-S), combined with the neutral conductor (TN-C), or both (TN-C-S). These are discussed below.\r\n\r\nTyper av TN-n\u00e4tverk<\/strong>\r\n\r\nIn a TN earthing system, one of the points in the generator or transformer is connected with earth, usually the star point in a three-phase system. The body of the electrical device is connected with earth via this earth connection at the transformer. This arrangement is a current standard for residential and industrial electric systems particularly in Europe.\r\n\r\nThe conductor that connects the exposed metallic parts of the consumer\u2019s electrical installation is called protective earth (PE; see also: Ground). The conductor that connects to the star point in a three-phase system, or that carries the return current in a single-phase system, is called neutral (N). Three variants of TN systems are distinguished:\r\n\r\nTN\u2212S<\/strong>\r\n\r\nPE och N \u00e4r separata ledare som \u00e4r sammankopplade endast n\u00e4ra str\u00f6mk\u00e4llan.\r\n\r\n\"\"\r\n\r\nTN\u2212C<\/strong>\r\n\r\nEn kombinerad PEN-ledare fyller funktionerna f\u00f6r b\u00e5de en PE- och en N-ledare. (P\u00e5 230\/400 V-system anv\u00e4nds normalt endast f\u00f6r distributionsn\u00e4t)\r\n\r\n\"\"\r\n\r\nTN\u2212C\u2212S<\/strong>\r\n\r\nEn del av systemet anv\u00e4nder en kombinerad PEN-ledare, som n\u00e5gon g\u00e5ng delas upp i separata PE- och N-linjer. Den kombinerade PEN-ledaren uppst\u00e5r vanligtvis mellan transformatorstationen och ing\u00e5ngspunkten till byggnaden, och jord och noll \u00e4r separerade i servicehuvudet. I Storbritannien \u00e4r detta system ocks\u00e5 k\u00e4nt som skyddande multipel jordning (PME), p\u00e5 grund av bruket att ansluta den kombinerade noll- och jordledaren via den kortaste m\u00f6jliga v\u00e4gen till lokala jordstavar vid k\u00e4llanoch med intervaller l\u00e4ngs distributionsn\u00e4ten till varje lokal, f\u00f6r att tillhandah\u00e5lla b\u00e5de systemjordning och utrustningsjordning p\u00e5 var och en av dessa platser. Liknande system i Australien och Nya Zeeland \u00e4r betecknade som multipeljordade neutrala (MEN) och, i Nordamerika, som multijordade neutrala (MGN).\r\n\r\n\"\"\r\n\r\nTT n\u00e4tverk<\/strong>\r\n\r\nI ett TT-jordsystem tillhandah\u00e5lls den skyddande jordanslutningen f\u00f6r konsumenten av en lokal jordelektrod, och det finns en annan oberoende installerad vid generatorn. Det finns ingen \u2018jordtr\u00e5d\u2019 mellan de tv\u00e5. Felslingimpedansen \u00e4r h\u00f6gre, och om inte elektrodimpedansen \u00e4r mycket l\u00e5g, b\u00f6r en TT-installation alltid ha en RCD (GFCI) som sin f\u00f6rsta isolator.\r\n\r\n\"\"\r\n\r\nIT-n\u00e4tverk<\/strong>\r\n\r\nI ett IT-n\u00e4t har det elektriska distributionssystemet ingen koppling till jord alls, eller s\u00e5 har det bara en h\u00f6gimpedansanslutning.\r\n\r\n\"\"","protected":false},"featured_media":780,"parent":0,"menu_order":183,"template":"","meta":{"_acf_changed":false},"blog_category":[8],"class_list":["post-758","blog","type-blog","status-publish","has-post-thumbnail","hentry","blog_category-company-news"],"acf":{"des":"International standard IEC 60364 distinguishes three families of earthing arrangements, using the two-letter codes TN, TT, and IT.","txt":"IEC terminology<\/strong>\r\n\r\nInternational standard IEC 60364 distinguishes three families of earthing arrangements, using the two-letter codes TN, TT, and IT.\r\n\r\nThe first letter indicates the connection between earth and the power-supply equipment (generator or transformer):\r\n\r\n\u201cT\u201d \u2014 Direct connection of a point with earth\r\n\r\n\u201cI\u201d \u2014 No point is connected with earth, except perhaps via high impedance.\r\n\r\nThe second letter indicates the connection between earth or network and the electrical device being supplied:\r\n\r\n\u201cT\u201d \u2014 Earth connection is by a local direct connection to earth, usually via a ground rod.\r\n\r\n\u201cN\u201d \u2014 the earth connection is supplied by the electricity supply network, either separately to the neutral conductor (TN-S), combined with the neutral conductor (TN-C), or both (TN-C-S). These are discussed below.\r\n\r\nTypes of TN networks<\/strong>\r\n\r\nIn a TN earthing system, one of the points in the generator or transformer is connected with earth, usually the star point in a three-phase system. The body of the electrical device is connected with earth via this earth connection at the transformer. This arrangement is a current standard for residential and industrial electric systems particularly in Europe.\r\n\r\nThe conductor that connects the exposed metallic parts of the consumer\u2019s electrical installation is called protective earth (PE; see also: Ground). The conductor that connects to the star point in a three-phase system, or that carries the return current in a single-phase system, is called neutral (N). Three variants of TN systems are distinguished:\r\n\r\nTN\u2212S<\/strong>\r\n\r\nPE and N are separate conductors that are connected together only near the power source.\r\n\r\n\"\"\r\n\r\nTN\u2212C<\/strong>\r\n\r\nA combined PEN conductor fulfills the functions of both a PE and an N conductor. (On 230\/400 V systems normally only used for distribution networks)\r\n\r\n\"\"\r\n\r\nTN\u2212C\u2212S<\/strong>\r\n\r\nPart of the system uses a combined PEN conductor, which is at some point split up into separate PE and N lines. The combined PEN conductor typically occurs between the substation and the entry point into the building, and earth and neutral are separated in the service head. In the UK, this system is also known as protective multiple earthing (PME), because of the practice of connecting the combined neutral-and-earth conductor via the shortest practicable route to local earth rods at the source and at intervals along the distribution networks to each premises, to provide both system earthing and equipment earthing at each of these locations. Similar systems in Australia and New Zealand are designated as multiple earthed neutral (MEN) and, in North America, as multi-grounded neutral (MGN).\r\n\r\n\"\"\r\n\r\nTT network<\/strong>\r\n\r\nIn a TT earthing system, the protective earth connection for the consumer is provided by a local earth electrode, and there is another independently installed at the generator. There is no \u2018earth wire\u2019 between the two. The fault loop impedance is higher, and unless the electrode impedance is very low indeed, a TT installation should always have an RCD (GFCI) as its first isolator.\r\n\r\n\"\"\r\n\r\nIT network<\/strong>\r\n\r\nIn an IT network, the electrical distribution system has no connection to earth at all, or it has only a high-impedance connection.\r\n\r\n\"\""},"_links":{"self":[{"href":"https:\/\/www.britecelectric.com\/sv\/wp-json\/wp\/v2\/blog\/758","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.britecelectric.com\/sv\/wp-json\/wp\/v2\/blog"}],"about":[{"href":"https:\/\/www.britecelectric.com\/sv\/wp-json\/wp\/v2\/types\/blog"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.britecelectric.com\/sv\/wp-json\/wp\/v2\/media\/780"}],"wp:attachment":[{"href":"https:\/\/www.britecelectric.com\/sv\/wp-json\/wp\/v2\/media?parent=758"}],"wp:term":[{"taxonomy":"blog_category","embeddable":true,"href":"https:\/\/www.britecelectric.com\/sv\/wp-json\/wp\/v2\/blog_category?post=758"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}