{"id":797,"date":"2023-12-19T16:31:05","date_gmt":"2023-12-19T08:31:05","guid":{"rendered":"https:\/\/www.britecelectric.com\/?post_type=blog&p=797"},"modified":"2024-09-05T16:36:33","modified_gmt":"2024-09-05T08:36:33","slug":"surge-protector-faq","status":"publish","type":"blog","link":"https:\/\/www.britecelectric.com\/da\/blog\/surge-protector-faq\/","title":{"rendered":"Oversp\u00e6ndingsbeskytter ofte stillede sp\u00f8rgsm\u00e5l"},"content":{"rendered":"Holder oversp\u00e6ndingsbeskyttere evigt?<\/strong>\r\n\r\nNej, det g\u00f8r de ikke. Hver gang en oversp\u00e6ndingsbeskytter omdirigerer en str\u00f8mst\u00f8d v\u00e6k fra dit tilsluttede udstyr, tager den indre struktur af beskytteren en lille smule skade. Med tiden holder de dele af oversp\u00e6ndingsbeskytteren, der holder dit tilsluttede udstyr sikkert, simpelthen op med at fungere. Hvor lang tid dette tager afh\u00e6nger af frekvensen og styrken af \u200b\u200bstr\u00f8mst\u00f8d.\r\n\r\nEr de eksisterende beskyttelser som MCB, ELCB etc. ikke tilstr\u00e6kkelige til at beskytte mod oversp\u00e6ndinger?<\/strong>\r\n\r\nAll the existing protecting devices like MCB, ELCB etc. are current sensitive devices. They get activated based on a fault current. These devices are triggered when the fault current persists for duration of more than 3 to 20 milliseconds. However, the surge typically lasts for a few micro seconds only during which time it causes all the damage.\r\n\r\nHence the conventional devices like MCB, ELCB fuses etc. are not effective in protection against surges. In view of the above, special equipment called surge protection device which has a response time of two nanoseconds is required to be installed to protect against the surges.\r\n\r\nHvad er en str\u00f8mst\u00f8d?<\/strong>\r\n\r\nEn str\u00f8mst\u00f8d er en stigning i den elektriske str\u00f8m, der str\u00f8mmer gennem ledningerne i dit hus. De kan beskadige almindelige apparater, f\u00f8lsom AV-elektronik og computerudstyr.\r\n\r\nHvilke forskellige teknologier bruges i SPD'er?<\/strong>\r\n\r\nNogle af de popul\u00e6re teknologier, der bruges i SPD'er, er f\u00f8lgende:\r\n
    \r\n \t
  1. i) Gasudledningsr\u00f8r<\/li>\r\n \t
  2. ii) Metaloxidvaristorer<\/li>\r\n<\/ol>\r\niii) Gnistgab\r\n
      \r\n \t
    1. iv) Zenerdiode<\/li>\r\n \t
    2. v) Silicium lavinedioder<\/li>\r\n<\/ol>\r\nBlandt disse er gasudladningsr\u00f8r, metaloxidvaristorer og gnistgab de mest popul\u00e6re typer oversp\u00e6ndingsafledere.\r\n\r\nHvad for\u00e5rsager en str\u00f8mst\u00f8d?<\/strong>\r\n\r\nDe fleste str\u00f8mst\u00f8d stammer fra inde i dit hjem. Str\u00f8mst\u00f8d er for\u00e5rsaget af mange forskellige faktorer, herunder h\u00e5rdt vejr, defekte eller beskadigede elektriske ledninger eller pludselig t\u00e6nding og slukning af en h\u00f8jeffekt elektrisk enhed som et klimaanl\u00e6g eller en stor elektrisk motor.\r\n\r\nSkal SPD-klassificeringerne v\u00e6lges afh\u00e6ngigt af linjestr\u00f8mmen?<\/strong>\r\n\r\nGenerelt er de SPD'er, der er installeret p\u00e5 det elektriske str\u00f8mkredsl\u00f8b, forbundet parallelt og vil derfor v\u00e6re uafh\u00e6ngige af belastningsstr\u00f8m (linje).\r\n\r\nHvorfor bekymre sig om str\u00f8mst\u00f8d?<\/strong>\r\n\r\nSt\u00e6rke str\u00f8mst\u00f8d kan udslette dit hjemmeudstyr p\u00e5 et \u00f8jeblik. Ud over stigninger for\u00e5rsaget af storme, kan det gennemsnitlige hjem opleve flere \u201cskjulte\u201d b\u00f8lger om dagen fra andre forskellige kilder. Disse mindre oversp\u00e6ndinger for\u00e5rsager kumulativ skade p\u00e5 elektronik, forkorter deres levetid og f\u00e5r dem til at svigte.\r\n\r\nHvordan bestemmer man, hvilke typer SPD'er, der skal installeres p\u00e5 et givet sted?<\/strong>\r\n\r\nUdv\u00e6lgelsen af \u200b\u200bSPD'er p\u00e5 et givet sted afh\u00e6nger af:\r\n
        \r\n \t
      1. a) Lokationens topografi i form af lynnedslag.<\/li>\r\n \t
      2. b) Tilb\u00f8jelighed til at skifte oversp\u00e6nding i form af n\u00e6rhed til store belastninger \/ tilsluttet landdistriktsf\u00f8der mv.<\/li>\r\n \t
      3. c) F\u00f8lsomhed af udstyret tilsluttet kredsl\u00f8bet.<\/li>\r\n<\/ol>\r\nNormally SPDs with Class-B & C are installed at the main panels and SPDs with Class-C rate are installed at the sub panels. The ratings for class-B, SPDs shall be a minimum of 12.5 KA Iimp.\r\n\r\nFor the Class-C (Imax. rating), it should be, a minimum of 40 kA at the sub panels.\r\n\r\nFor the Class-D SPDs which are installed near sensitive equipment, the criteria shall be the residual voltage or the protection level which should be lower than the temporary over voltage withstanding capacity of the protected equipment.\r\n\r\nHvad g\u00f8r en oversp\u00e6ndingsbeskytter?<\/strong>\r\n\r\nEn oversp\u00e6ndingsbeskytter beskytter elektronikken mod de skadelige virkninger af str\u00f8mst\u00f8d og sp\u00e6ndingsspidser. Oversp\u00e6ndingsbeskyttere kan absorbere og sprede kraften fra en oversp\u00e6nding, s\u00e5 tilsluttet udstyr er afsk\u00e6rmet mod oversp\u00e6ndingen.\r\n\r\nHvordan ved man, at den installerede SPD virker?<\/strong>\r\n\r\nDa SPD'erne altid er forbundet parallelt med det elektriske kredsl\u00f8b, er det under det normale forl\u00f8b ikke muligt at vide, om de er i funktionsdygtig stand eller ej. Derfor er det n\u00f8dvendigt at have en lokal og fjernindikation ved hj\u00e6lp af elektrisk kontakt for at kende og overv\u00e5ge SPD'ens sundhed.\r\n\r\nEr det n\u00f8dvendigt at have separat jording til SPD'er?<\/strong>\r\n\r\nDet er ikke n\u00f8dvendigt at have en separat eller dedikeret jordforbindelse til SPD'er. SPD'erne skal altid tilsluttes det generelle jordnet.\r\n\r\nEr et godt jordingssystem n\u00f8dvendigt for effektiv drift af SPD'en?<\/strong>\r\n\r\nAlle SPD'er virker ved at aflede den overskydende energi til jorden. Derfor er det bydende n\u00f8dvendigt, at jordingssystemet, der er tilsluttet SPD'en, skal v\u00e6re i effektiv driftstilstand, s\u00e5 oversp\u00e6ndingsstr\u00f8mmen kan str\u00f8mme til jorden uden nogen hindring.\r\n\r\nEr SPD'er tilg\u00e6ngelige til andre applikationer end det elektriske kredsl\u00f8b som telefonlinjer, datalinjer osv.?<\/strong>\r\n\r\nSPD'er er bestemt tilg\u00e6ngelige for alle kredsl\u00f8b som telefonlinjer, datalinjer, Ethernet-linjer, signallinjer osv. I alle disse kredsl\u00f8b er SPD'er forbundet i serie.\r\n\r\nEr prim\u00e6re SPD'er alene tilstr\u00e6kkelige til udstyrsbeskyttelse?<\/strong>\r\n\r\nNej, fra et lille anl\u00e6g til et stort anl\u00e6g er det normalt n\u00f8dvendigt at anvende en kaskade- eller lagdelt tilgang, hvor prim\u00e6r beskyttelse er installeret ved serviceindgangspanelet og sekund\u00e6r beskyttelse ved grenpaneler. Hver facilitet kr\u00e6ver individuel analyse for at bestemme den rigtige beskyttelse til at opfylde behovene for det anvendte udstyr. Det kan endda v\u00e6re n\u00f8dvendigt at inkludere yderligere point-of-use SPD'er, hvis dette udstyr er placeret et stykke fra forsyningspanelet. En kaskade tilganganbefales af IEEE, og denne type tilgang vil give den mest effektive oversp\u00e6ndingsbeskyttelse i hele en facilitet. For mere information om, hvor du skal anvende SPD'er, skal du v\u00e6lge den type milj\u00f8, du er interesseret i: industri, kommerciel eller bolig.\r\n\r\nHvorfor har jeg brug for en SPD, n\u00e5r jeg allerede har en isolationstransformator?<\/strong>\r\n\r\nIsolationstransformatorer giver meget god common mode afvisning, men giver ikke god differentiel (normal) mode afvisning. Med andre ord vil en oversp\u00e6nding, der er overlejret ligeligt p\u00e5 b\u00e5de linje (L) og neutral (N) ledere, se afvisning af isolationstransformatoren, mens en oversp\u00e6nding, der optr\u00e6der forskelligt mellem L og N lederne, vil passere gennem transformeren. Husk ogs\u00e5, at de fleste transienter genereres af belastningerne i anl\u00e6gget p\u00e5 belastningssiden af \u200b\u200bdissetransformere. For at minimere virkningerne af disse internt genererede transienter fra et stykke udstyr til et andet b\u00f8r der placeres en SPD.","protected":false},"featured_media":798,"parent":0,"menu_order":176,"template":"","meta":{"_acf_changed":false},"blog_category":[8],"class_list":["post-797","blog","type-blog","status-publish","has-post-thumbnail","hentry","blog_category-company-news"],"acf":{"des":"Do surge protectors last forever?No, they do not. Each time a surge protector reroutes a power surge away from your connected equipment, the internal structure of the protector takes a little bit of damage.","txt":"Do surge protectors last forever?<\/strong>\r\n\r\nNo, they do not. Each time a surge protector reroutes a power surge away from your connected equipment, the internal structure of the protector takes a little bit of damage. Over time the parts of the surge protector that keep your connected equipment safe simply stop working. How long this takes depends on the frequency and strength of power surges.\r\n\r\nAre the existing protections like MCB, ELCB etc. not sufficient to protect against surges?<\/strong>\r\n\r\nAll the existing protecting devices like MCB, ELCB etc. are current sensitive devices. They get activated based on a fault current. These devices are triggered when the fault current persists for duration of more than 3 to 20 milliseconds. However, the surge typically lasts for a few micro seconds only during which time it causes all the damage.\r\n\r\nHence the conventional devices like MCB, ELCB fuses etc. are not effective in protection against surges. In view of the above, special equipment called surge protection device which has a response time of two nanoseconds is required to be installed to protect against the surges.\r\n\r\nWhat is a power surge?<\/strong>\r\n\r\nA power surge is a spike in the electrical current flowing through the wires of your house. They can damage common appliances, sensitive AV electronics and computer equipment.\r\n\r\nWhat are the different technologies used in SPDs?<\/strong>\r\n\r\nSome of the popular technologies used in SPDs are the following:\r\n
          \r\n \t
        1. i) Gas discharge tubes<\/li>\r\n \t
        2. ii) Metal oxide varistors<\/li>\r\n<\/ol>\r\niii) Spark gap\r\n
            \r\n \t
          1. iv) Zener diode<\/li>\r\n \t
          2. v) Silicon Avalanche diodes<\/li>\r\n<\/ol>\r\nAmong these, gas discharge tubes, metal oxide varistors and spark gap are the most popular types of surge arresters.\r\n\r\nWhat causes a power surge?<\/strong>\r\n\r\nMost power surges stem from inside your home. Power surges are caused by many different factors, including severe weather, faulty or damaged electric wiring or the sudden turning on and off of a high power electrical device like an air conditioner or large electric motor.\r\n\r\nAre the SPDs ratings to be selected depending on the line current?<\/strong>\r\n\r\nGenerally, the SPDs installed on the electrical Power circuit are connected in parallel and hence will be independent of load (line) current.\r\n\r\nWhy worry about power surges?<\/strong>\r\n\r\nStrong power surges can wipe out your home equipment in an instant. In addition to surges caused by storms, the average home can experience multiple \u201chidden\u201d surges a day from other various sources. These smaller surges cause cumulative damage to electronics, shortening their life and eventually causing them to fail.\r\n\r\nHow to determine what types of SPDs are to be installed at a given location?<\/strong>\r\n\r\nThe selection of SPDs at a given location depends on:\r\n
              \r\n \t
            1. a) The topography of the location in terms of lightning strikes.<\/li>\r\n \t
            2. b) Susceptibility to switching surges in terms of proximity to large loads \/ connected to rural feeder etc.<\/li>\r\n \t
            3. c) Sensitivity of the equipment connected to the circuit.<\/li>\r\n<\/ol>\r\nNormally SPDs with Class-B & C are installed at the main panels and SPDs with Class-C rate are installed at the sub panels. The ratings for class-B, SPDs shall be a minimum of 12.5 KA Iimp.\r\n\r\nFor the Class-C (Imax. rating), it should be, a minimum of 40 kA at the sub panels.\r\n\r\nFor the Class-D SPDs which are installed near sensitive equipment, the criteria shall be the residual voltage or the protection level which should be lower than the temporary over voltage withstanding capacity of the protected equipment.\r\n\r\nWhat does a surge protector do?<\/strong>\r\n\r\nA surge protector safeguards electronics from the harmful effects of power surges and voltage spikes. Surge protectors can absorb and dissipate the power of a surge so that connected equipment is shielded from the surge.\r\n\r\nHow does one know the SPD installed is working?<\/strong>\r\n\r\nSince the SPDs are always connected in parallel to the electrical circuit, during the normal course it is not possible to know whether they are in working condition or not. Hence it is necessary to have a local and remote indication using electrical contact in order to know and monitor the healthiness of the SPD.\r\n\r\nIs it necessary for having separate grounding for SPDs?<\/strong>\r\n\r\nIt is not necessary to have a separate or dedicated grounding for SPDs. The SPDs should always be connected to the general earth grid.\r\n\r\nIs a good earthing system necessary for efficient working of the SPD?<\/strong>\r\n\r\nAll SPDs work by diverting the excess energy to the ground. Hence it is imperative that the earthing system connected to the SPD must be in efficient working condition so that the surge current can flow to the earth without any hindrance.\r\n\r\nAre SPDs available for applications other than the electrical circuit like telephone lines, data lines etc.?<\/strong>\r\n\r\nSPDs are certainly available for every circuit like telephone lines, data lines, Ethernet lines, signal lines etc. In all these circuits SPDs are connected in series.\r\n\r\nAre primary SPDs alone sufficient for equipment protection?<\/strong>\r\n\r\nNo, from a small facility to a large facility, it is usually necessary to adopt a cascaded or layered approach where primary protection is installed at the service entrance panel, and secondary protection at branch panels. Each facility requires individual analysis to determine the right protection to meet the needs of the equipment being used. It can even be necessary to include additional point-of-use SPDs if this equipment is located some distance from the supplying panel. A cascaded approach is recommended by the IEEE and this type of approach will provide the most effective surge protection throughout a facility. For more information on where to apply SPDs, select the type of environment you\u2019re interested in: industrial, commercial, or residential.\r\n\r\nWhy do I need an SPD when I already have an isolation transformer?<\/strong>\r\n\r\nIsolation transformers provide very good common mode rejection but do not provide good differential (normal) mode rejection. In other words, a surge superimposed equally on both the line (L) and neutral (N) conductors will see rejection by the isolation transformer, while a surge appearing differentially between the L and N conductors will pass through the transformer. Also, keep in mind the majority of transients are being generated by the loads within the facility, on the load side of these transformers. To minimize the effects of these internally generated transients from one piece of equipment to another an SPD should be placed."},"_links":{"self":[{"href":"https:\/\/www.britecelectric.com\/da\/wp-json\/wp\/v2\/blog\/797","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.britecelectric.com\/da\/wp-json\/wp\/v2\/blog"}],"about":[{"href":"https:\/\/www.britecelectric.com\/da\/wp-json\/wp\/v2\/types\/blog"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.britecelectric.com\/da\/wp-json\/wp\/v2\/media\/798"}],"wp:attachment":[{"href":"https:\/\/www.britecelectric.com\/da\/wp-json\/wp\/v2\/media?parent=797"}],"wp:term":[{"taxonomy":"blog_category","embeddable":true,"href":"https:\/\/www.britecelectric.com\/da\/wp-json\/wp\/v2\/blog_category?post=797"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}