{"id":3855,"date":"2020-02-29T12:14:45","date_gmt":"2020-02-29T09:14:45","guid":{"rendered":"http:\/\/www.benga.pro\/?p=3855"},"modified":"2020-02-29T12:14:45","modified_gmt":"2020-02-29T09:14:45","slug":"kablo-ve-iletkenlerin-korunmasi","status":"publish","type":"post","link":"https:\/\/benga.pro\/index.php\/2020\/02\/29\/kablo-ve-iletkenlerin-korunmasi\/","title":{"rendered":"Kablo ve \u0130letkenlerin Korunmas\u0131"},"content":{"rendered":"<p>\u0130letkenler ister bak\u0131r olsun ister al\u00fcminyum olsun asl\u0131nda, ergime s\u0131cakl\u0131\u011f\u0131n\u0131n alt\u0131nda oldu\u011fu s\u00fcrece, y\u00fczlerce derece s\u0131cakl\u0131klarda y\u00fcklenebilirler. Ama ger\u00e7ekte bunu uygulamak m\u00fcmk\u00fcn olmamaktad\u0131r \u00e7\u00fcnk\u00fc gerek \u0131s\u0131l gerekse elektriksel anlamda iletkenleri yal\u0131tmak durumunday\u0131z. Yal\u0131t\u0131m malzemeleri ise bak\u0131r, al\u00fcminyum metallerinin aksine olduk\u00e7a d\u00fc\u015f\u00fck s\u0131cakl\u0131klara dayanabilmektedir.<\/p>\n<p>Yayg\u0131n 2 t\u00fcr yal\u0131t\u0131mdan biri olan thermoplastic (PVC) yal\u0131t\u0131m 70\u00baC s\u0131cakl\u0131\u011fa kadar, thermosetting (XLPE, EDR) yal\u0131t\u0131m ise 90\u00baC s\u0131cakl\u0131\u011fa kadar yap\u0131lar\u0131nda bir de\u011fi\u015fiklik olmadan yal\u0131t\u0131m vazifelerini yerine getirebilirler. Bu \u015fu demektir: PVC yal\u0131t\u0131ml\u0131 bir iletkeni, iletkenin s\u0131cakl\u0131\u011f\u0131 70\u00baC ye ula\u015f\u0131ncaya kadar y\u00fckleyebiliriz. Yal\u0131t\u0131m\u0131n i\u00e7 taraf\u0131nda yani iletkene temas eden y\u00fczeyi 70\u00baC ye maruz kalacakt\u0131r. D\u0131\u015f ortama bakan taraf\u0131 ise elbette 70\u00baC den daha d\u00fc\u015f\u00fck bir s\u0131cakl\u0131kta olacakt\u0131r, d\u0131\u015f ortam\u0131n \u0131s\u0131 iletme kabiliyetine ba\u011fl\u0131 olarak hesapla bulunabilir.\u00a0 Belki 50\u00baC belki 40\u00baC olacakt\u0131r ama bu yaz\u0131m\u0131zda bu hesaba girmeyece\u011fiz. Bizim i\u00e7in \u015fimdi \u00f6nemli olan yal\u0131t\u0131m\u0131n i\u00e7 taraf\u0131n\u0131n temas etmekte oldu\u011fu iletkenin s\u0131cakl\u0131\u011f\u0131d\u0131r.<\/p>\n<p>Ancak kablolarda i\u015fletme s\u0131ras\u0131nda zaman zaman hata ak\u0131mlar\u0131 olu\u015fmayaca\u011f\u0131n\u0131n garantisi yoktur. %100 y\u00fckleyip 90\u00baC iletken s\u0131cakl\u0131\u011f\u0131nda \u00e7al\u0131\u015ft\u0131rmakta oldu\u011fumuz bir XLPE yal\u0131t\u0131ml\u0131 kablomuzda hata sonucu olu\u015fan k\u0131sa devrede \u00e7ok y\u00fcksek ak\u0131mlar ge\u00e7ecektir. Bu k\u0131sa devre ak\u0131m\u0131 iletkenin s\u0131cakl\u0131\u011f\u0131n\u0131 h\u0131zla 90\u00baC\u2019nin \u00fczerine artt\u0131racakt\u0131r. E\u011fer devre gerekli s\u00fcre i\u00e7inde kesilmezse, k\u0131sadevre ak\u0131m\u0131n\u0131n b\u00fcy\u00fckl\u00fc\u011f\u00fcne ba\u011fl\u0131 olarak iletkenin s\u0131cakl\u0131\u011f\u0131 artacak, artacak ve \u00f6nce kablonun yal\u0131t\u0131m\u0131, yal\u0131t\u0131m \u00f6zelli\u011fini kaybedecek, daha sonra alev alacak ve tats\u0131z \u015feyler olu\u015facakt\u0131r.<\/p>\n<p>Kablo \u00fcreticileri, kablolar\u0131n\u0131 hata durumlar\u0131nda\u00a0 thermoplastic (PVC) yal\u0131t\u0131ml\u0131 kablolar\u0131 160\u00baC s\u0131cakl\u0131\u011fa, thermosetting (XLPE, EDR) yal\u0131t\u0131ml\u0131 kablolar\u0131 ise 250\u00baC s\u0131cakl\u0131\u011fa 5 saniye s\u00fcreyle dayanacak \u015fekilde \u00fcretirler. Yani devre tasar\u0131m\u0131n\u0131 yaparken bu s\u0131n\u0131rlar i\u00e7inde kalmam\u0131z, kablolar s\u0131n\u0131r s\u0131cakl\u0131klara ula\u015fmadan devreyi kesmemiz gerekir. Bu s\u0131n\u0131r de\u011ferlerini a\u015fmazsak kablolar\u0131n yal\u0131t\u0131m\u0131nda yap\u0131sal bir hasar olmaz ve kullan\u0131lmaya devam eder.<\/p>\n<p>Elimizde s\u00fcre bilgisi var, i\u015fletme ve s\u0131n\u0131r s\u0131cakl\u0131klar\u0131 aras\u0131ndaki s\u0131cakl\u0131k fark\u0131 var. O halde bu kriter bize bir \u0131s\u0131 enerjisi miktar\u0131n\u0131 ifade ediyor. \u00d6rne\u011fin 90\u00baC iletken s\u0131cakl\u0131\u011f\u0131nda \u00e7al\u0131\u015fan kablomuzda olu\u015fan bir k\u0131sa devre sonucu s\u0131cakl\u0131k y\u00fckseliyorsa, kabloda normalden fazla ilave bir \u0131s\u0131 enerjisi \u00fcretilmeye ba\u015flam\u0131\u015ft\u0131r. Is\u0131 enerjisi art\u0131\u015f\u0131 iletken s\u0131cakl\u0131\u011f\u0131n\u0131 250\u00baCyi\u00a0 a\u015fmadan devrenin kesilmesi laz\u0131md\u0131r.<\/p>\n<p>Bu ili\u015fkileri matematiksel ba\u011f\u0131nt\u0131lar\u0131 kullanarak yaparsak, konu daha iyi anla\u015f\u0131lacakt\u0131r:<\/p>\n<h5><strong>Adyabatik Durum Denklemleri<\/strong><\/h5>\n<p>Adyabatik terimi, bir proses esnas\u0131nda \u00e7evre ile enerji al\u0131\u015fveri\u015finin olmad\u0131\u011f\u0131 durumu ifade eder. Kablonun \u0131s\u0131nmas\u0131 olay\u0131 adyabatik bir proses olarak d\u00fc\u015f\u00fcn\u00fcl\u00fcp buna g\u00f6re form\u00fcllendirilir. Asl\u0131nda \u0131s\u0131nan kablo bir \u015fekilde \u00e7evreye \u0131s\u0131s\u0131n\u0131 yayar ve s\u0131n\u0131r s\u0131cakl\u0131klara ula\u015fmas\u0131 daha zorla\u015f\u0131r ama bunu g\u00f6zard\u0131 etmek form\u00fcllerin hem daha g\u00fcvenli tarafta kalmas\u0131n\u0131 sa\u011flar hem de hesaplama kolayl\u0131\u011f\u0131 sa\u011flar.<\/p>\n<p>Is\u0131 enerjisi form\u00fcl\u00fcn\u00fc hat\u0131rlayal\u0131m:<\/p>\n<p>Q = C m \u0394T\u00a0<strong>\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 (1)<\/strong><\/p>\n<p>Q\u00a0\u2013 \u0131s\u0131 enerjisi, J<br \/>\nC\u00a0\u2013 malzemenin \u00f6zg\u00fcl \u0131s\u0131, J.g<sup>-1<\/sup>.K<sup>-1<\/sup><br \/>\nm\u00a0\u2013 malzemenin a\u011f\u0131rl\u0131\u011f\u0131, g<br \/>\n\u0394T\u00a0\u2013 s\u0131cakl\u0131k fark\u0131, K<\/p>\n<p>Di\u011fer taraftan, iletken \u00fczerinde olu\u015fan \u0131s\u0131 enerjisi ise<\/p>\n<p>Q = I<sup>2<\/sup> R t\u00a0 \u00a0 <strong>\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0(2)<\/strong><\/p>\n<p>R \u2013\u00a0iletkenin direnci, \u03a9<br \/>\nI\u00a0\u2013 iletkenden ge\u00e7en ak\u0131m, A<br \/>\nt\u00a0\u2013 s\u00fcre, s<\/p>\n<p>Bu durumda her iki ifadeyi birbirine e\u015fitleyebiliriz:<\/p>\n<p>C m \u0394T\u00a0=\u00a0I<sup>2<\/sup> R t\u00a0\u00a0\u00a0 <strong>\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0(3)<\/strong><\/p>\n<p>Malzemenin a\u011f\u0131rl\u0131\u011f\u0131 (m), yo\u011funlu\u011fu(\u03c1<sub>c<\/sub>\u00a0) ve hacmin \u00e7arp\u0131m\u0131d\u0131r. Hacim, kesit alan\u0131(S) ve uzunlu\u011fun(L) \u00e7arp\u0131m\u0131d\u0131r. Malzemenin direnci(R) ise \u00f6zg\u00fcl direncinin(\u03c1<sub>r<\/sub>\u00a0)uzunluk(L) ile \u00e7arp\u0131m\u0131n\u0131n kesite(s) oran\u0131d\u0131r.<\/p>\n<p>m=\u03c1c\u00a0S\u00a0L<strong>\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0(4)<\/strong><\/p>\n<p>R= \u03c1<sub>r<\/sub> L \/ S<strong>\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0(5)<\/strong><\/p>\n<p>\u03c1<sub>c<\/sub>\u00a0\u2013 malzemenin yo\u011funlu\u011fu g.mm<sup>-3<\/sup><br \/>\n\u03c1<sub>r<\/sub>\u00a0\u2013 malzemenin \u00f6zg\u00fcl direnci, \u03a9.mm<br \/>\nL\u00a0\u2013 \u0130letken uzunlu\u011fu, mm<\/p>\n<p>3 numaral\u0131 denklemde 4 ve 5 numaral\u0131 ba\u011f\u0131nt\u0131lar\u0131 kullan\u0131rsak:<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-3869\" src=\"http:\/\/www.benga.pro\/wp-content\/uploads\/2020\/02\/2-300x141.jpg\" alt=\"\" width=\"268\" height=\"126\" \/><\/p>\n<p>Ula\u015ft\u0131\u011f\u0131m\u0131z 6 numaral\u0131 ba\u011f\u0131nt\u0131da bir tan\u0131m yapal\u0131m ve k ad\u0131nda bir de\u011fi\u015fken tan\u0131mlayal\u0131m:<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-3871\" src=\"http:\/\/www.benga.pro\/wp-content\/uploads\/2020\/02\/1.jpg\" alt=\"\" width=\"103\" height=\"54\" \/><\/p>\n<p>olsun. Bu durumda 6 numaral\u0131 ba\u011f\u0131nt\u0131m\u0131z \u015fu hale gelecektir.<\/p>\n<p>k<sup>2<\/sup> S<sup>2<\/sup> = I<sup>2<\/sup> t\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0<strong>\u00a0\u00a0\u00a0 \u00a0\u00a0(7)<\/strong><\/p>\n<p>Bu ba\u011f\u0131nt\u0131 ile devremizde bir hata olu\u015ftu\u011funda, hata s\u00fcresi boyunca kablo \u00fczerinde olu\u015facak \u0131s\u0131 enerjisini tespit edebiliriz. Dolay\u0131s\u0131yla, s\u0131cakl\u0131k fark\u0131n\u0131 ifade eden \u00a0ve s\u00fcreyi ifade eden t ile s\u0131n\u0131r s\u0131cakl\u0131\u011f\u0131na ula\u015f\u0131p ula\u015f\u0131lmad\u0131\u011f\u0131n\u0131 kontrol eder, kabul edilecek bir s\u00fcre i\u00e7inde devreyi keseriz.<\/p>\n<h5><strong>k katsay\u0131s\u0131n\u0131n irdelenmesi<\/strong><\/h5>\n<p><strong>k<sup>2<\/sup> S<sup>2<\/sup> = I<sup>2<\/sup> t\u00a0 \u00a0 \u00a0 \u00a0 <\/strong>ba\u011f\u0131nt\u0131s\u0131, daha \u00f6nce de vurguland\u0131\u011f\u0131 gibi adyabatik bir ortam oldu\u011fu d\u00fc\u015f\u00fcn\u00fclerek t\u00fcretilmi\u015ftir. Sadece hata esnas\u0131nda hata s\u00fcresi boyunca kullan\u0131lacak bir ba\u011f\u0131nt\u0131d\u0131r. Kablonun normal \u00e7al\u0131\u015fma durumunda bu ba\u011f\u0131nt\u0131 kullan\u0131lamaz. \u00c7\u00fcnk\u00fc normal \u00e7al\u0131\u015fma adyabatik olarak de\u011ferlendirilemez. Kablo, bulundu\u011fu d\u0131\u015f ortama \u0131s\u0131 verir, ortam s\u0131cakl\u0131\u011f\u0131 ile aras\u0131nda bir denge olu\u015fur ve kablo iletime devam eder.<\/p>\n<p>Adyabatik yani \u00e7evreyle \u0131s\u0131 al\u0131\u015fveri\u015fi olmad\u0131\u011f\u0131n\u0131 d\u00fc\u015f\u00fcnsek, kabloyu hi\u00e7 kullanamay\u0131z. \u00c7\u00fcnk\u00fc bir kablo saatlerce, g\u00fcnlerce, aylarca, y\u0131llarca gerilim alt\u0131nda olabilir. 7 numaral\u0131 ba\u011f\u0131nt\u0131daki s\u00fcre (t) de\u011fi\u015fkenine \u00e7ok b\u00fcy\u00fck de\u011ferler koyarsak ak\u0131m (I) de\u011ferinin \u00e7ok azalmas\u0131 gerekir ki anlams\u0131z bir durum olur.<\/p>\n<p>k katsay\u0131s\u0131 i\u00e7in a\u015fa\u011f\u0131daki ba\u011f\u0131nt\u0131ya ula\u015fm\u0131\u015ft\u0131k.<\/p>\n<p><strong>\u00a0 <img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"http:\/\/www.benga.pro\/wp-content\/uploads\/2020\/02\/1.jpg\" width=\"109\" height=\"57\" \/>\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0<\/strong><\/p>\n<p>\u0394T ifadesi iletkeninin hatan\u0131n olu\u015ftu\u011fu andaki s\u0131cakl\u0131k de\u011feri ile s\u0131n\u0131r s\u0131cakl\u0131k de\u011feri aras\u0131ndaki farkt\u0131r. Ancak hatan\u0131n ne zaman olu\u015faca\u011f\u0131n\u0131 bilemeyece\u011fimizden dolay\u0131, iletkenin bulundu\u011fu s\u0131cakl\u0131\u011f\u0131 da kestiremeyiz. Belki o anda iletken %30 y\u00fck ile \u00e7al\u0131\u015f\u0131yordur, iletken s\u0131cakl\u0131\u011f\u0131 40-50\u00baC dir, belki %50 y\u00fck ile \u00e7al\u0131\u015f\u0131yordur, iletken s\u0131cakl\u0131\u011f\u0131 60-70\u00baC dir, belki %100 y\u00fck ile \u00e7al\u0131\u015f\u0131yordur ve s\u0131cakl\u0131k 90\u00baC dir. Bu durumda yap\u0131lacak en g\u00fcvenli \u015fey, hatan\u0131n olu\u015ftu\u011fu andaki iletken s\u0131cakl\u0131\u011f\u0131n\u0131 90\u00baC kabul etmektir.<\/p>\n<p>C, \u03c1c, \u03c1r de\u011ferleri asl\u0131nda sabit olmay\u0131p s\u0131cakl\u0131k ile de\u011fi\u015fen de\u011ferlerdir. \u0130letkenin s\u0131cakl\u0131\u011f\u0131 artt\u0131k\u00e7a yo\u011funlu\u011fu, \u00f6zg\u00fcl direnci ve \u00f6zg\u00fcl \u0131s\u0131s\u0131 da de\u011fi\u015fecektir. Bu de\u011fi\u015fimleri de g\u00f6z \u00f6n\u00fcne al\u0131nmas\u0131 durumunda k de\u011ferini veren form\u00fcl\u00fcm\u00fcz, IEC 60364-5-54 de g\u00f6sterilen hali alacakt\u0131r.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-medium wp-image-3872\" src=\"http:\/\/www.benga.pro\/wp-content\/uploads\/2020\/02\/3-300x58.jpg\" alt=\"\" width=\"300\" height=\"58\" \/><\/p>\n<p>Q<sub>c<\/sub>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 20\u00b0C s\u0131cakl\u0131kta iletkenin \u00f6zg\u00fcl \u0131s\u0131s\u0131, J.K-1.mm-3<br \/>\n\u00df\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 0 \u00b0C s\u0131cakl\u0131kta direncin s\u0131cakl\u0131k katsay\u0131n\u0131n tersi<br \/>\n\u03c1<sub>20<\/sub>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 20 \u00b0C s\u0131cakl\u0131kta iletkenin elektriksel direnci, \u03a9.mm<br \/>\n\u03f4<sub>i<\/sub>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 iletkenin ilk s\u0131cakl\u0131\u011f\u0131, \u00b0C<br \/>\n\u03f4<sub>f<\/sub>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 iletkenin son s\u0131cakl\u0131\u011f\u0131, \u00b0C<\/p>\n<p>Bak\u0131r, al\u00fcminyum ve \u00e7elik i\u00e7in Qc, \u00df, \u03c1<sub>20 <\/sub>de\u011ferleri sabittir ve a\u015fa\u011f\u0131daki tabloda verebiliriz.<\/p>\n<table width=\"0\">\n<tbody>\n<tr>\n<td width=\"111\">\n<p style=\"text-align: center;\">\n<\/td>\n<td style=\"text-align: center;\" width=\"69\">\u00a0\u00df<\/p>\n<p>[\u00b0C]<\/td>\n<td style=\"text-align: center;\" width=\"113\">Q<sub>c<\/sub><\/p>\n<p>[J.K<sup>-1<\/sup>.mm<sup>-3<\/sup>]<\/td>\n<td style=\"text-align: center;\" width=\"104\">\u03c1<sub>20<\/sub><\/p>\n<p>[\u03a9.mm]<\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: center;\" width=\"111\">Bak\u0131r<\/td>\n<td style=\"text-align: center;\" width=\"69\">234.5<\/td>\n<td style=\"text-align: center;\" width=\"113\">3.45 x 10<sup>-3<\/sup><\/td>\n<td width=\"104\">\n<p style=\"text-align: center;\">17.241 x 10<sup>-6<\/sup><\/p>\n<\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: center;\" width=\"111\">Al\u00fcminyum<\/td>\n<td style=\"text-align: center;\" width=\"69\">228<\/td>\n<td style=\"text-align: center;\" width=\"113\">2.5 x 10<sup>-3<\/sup><\/td>\n<td width=\"104\">\n<p style=\"text-align: center;\">28.267 x 10<sup>-6<\/sup><\/p>\n<\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: center;\" width=\"111\">\u00c7elik<\/td>\n<td style=\"text-align: center;\" width=\"69\">202<\/td>\n<td style=\"text-align: center;\" width=\"113\">3.8 x 10<sup>-3<\/sup><\/td>\n<td width=\"104\">\n<p style=\"text-align: center;\">138 x 10<sup>-6<\/sup><\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>8 numaral\u0131 ba\u011f\u0131nt\u0131da tablodaki de\u011ferleri kullanarak bak\u0131r, al\u00fcminyum ve \u00e7elik i\u00e7in ayr\u0131 ayr\u0131 olarak k de\u011ferini veren ba\u011f\u0131nt\u0131y\u0131 olu\u015fturabiliriz.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-medium wp-image-3873\" src=\"http:\/\/www.benga.pro\/wp-content\/uploads\/2020\/02\/4-300x250.jpg\" alt=\"\" width=\"300\" height=\"250\" \/><\/p>\n<p>Bir hata an\u0131nda belli bir s\u00fcre i\u00e7in \u00e7\u0131k\u0131labilecek s\u0131n\u0131r s\u0131cakl\u0131klar kablo \u00fcreticileri ve standartlarda tan\u0131mland\u0131\u011f\u0131n\u0131 s\u00f6ylemi\u015ftik. Bu s\u0131cakl\u0131k de\u011ferlerini ve 9-10-11 numaral\u0131 ba\u011f\u0131nt\u0131lar\u0131 kullanarak k de\u011ferlerini, <em>sadece o s\u0131cakl\u0131k aral\u0131\u011f\u0131 i\u00e7in olmak kayd\u0131yla<\/em>, bulabiliriz.<\/p>\n<table width=\"0\">\n<tbody>\n<tr>\n<td width=\"176\"><\/td>\n<td width=\"64\"><\/td>\n<td width=\"64\"><\/td>\n<td colspan=\"3\" width=\"228\"><strong>k<\/strong><\/td>\n<\/tr>\n<tr>\n<td width=\"176\"><strong>Yal\u0131t\u0131m\u0131n T\u00fcr\u00fc<\/strong><\/td>\n<td width=\"64\"><strong>\u03f4<\/strong><strong><sub>i<\/sub><\/strong><strong>\u00a0(\u00baC)<\/strong><\/td>\n<td width=\"64\"><strong>\u03f4<\/strong><strong><sub>f<\/sub><\/strong><strong>\u00a0(\u00baC)<\/strong><\/td>\n<td width=\"55\"><strong>Bak\u0131r<\/strong><\/td>\n<td width=\"121\"><strong>Al\u00fcminyum<\/strong><\/td>\n<td width=\"52\"><strong>\u00c7elik<\/strong><\/td>\n<\/tr>\n<tr>\n<td width=\"176\">Termoplastik (PVC)<\/td>\n<td width=\"64\">70<\/td>\n<td width=\"64\">160<\/td>\n<td width=\"55\">115<\/td>\n<td width=\"121\">76<\/td>\n<td width=\"52\">42<\/td>\n<\/tr>\n<tr>\n<td width=\"176\">Termoplastik (PVC)<\/td>\n<td width=\"64\">70<\/td>\n<td width=\"64\">140<\/td>\n<td width=\"55\">103<\/td>\n<td width=\"121\">68<\/td>\n<td width=\"52\">37<\/td>\n<\/tr>\n<tr>\n<td width=\"176\">Termoset (XLPE, EDR)<\/td>\n<td width=\"64\">90<\/td>\n<td width=\"64\">160<\/td>\n<td width=\"55\">100<\/td>\n<td width=\"121\">66<\/td>\n<td width=\"52\">36<\/td>\n<\/tr>\n<tr>\n<td width=\"176\">Termoset (XLPE, EDR)<\/td>\n<td width=\"64\">90<\/td>\n<td width=\"64\">250<\/td>\n<td width=\"55\">143<\/td>\n<td width=\"121\">94<\/td>\n<td width=\"52\">52<\/td>\n<\/tr>\n<tr>\n<td width=\"176\">Termoset (Lastik)<\/td>\n<td width=\"64\">60<\/td>\n<td width=\"64\">200<\/td>\n<td width=\"55\">141<\/td>\n<td width=\"121\">93<\/td>\n<td width=\"52\">51<\/td>\n<\/tr>\n<tr>\n<td width=\"176\">Termoset (Lastik)<\/td>\n<td width=\"64\">85<\/td>\n<td width=\"64\">220<\/td>\n<td width=\"55\">134<\/td>\n<td width=\"121\">89<\/td>\n<td width=\"52\">48<\/td>\n<\/tr>\n<tr>\n<td width=\"176\">Termoset (Silikon Lastik)<\/td>\n<td width=\"64\">180<\/td>\n<td width=\"64\">350<\/td>\n<td width=\"55\">132<\/td>\n<td width=\"121\">87<\/td>\n<td width=\"52\">47<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>&nbsp;<\/p>\n<h5>\u0130letkenin hata s\u00fcresince y\u00fcklenebilece\u011fi \u0131s\u0131 enerjisi<\/h5>\n<p>Yukar\u0131da, <strong>Q = C m \u0394T\u00a0 (1)<\/strong> ve <strong>Q = I<sup>2<\/sup> R t<\/strong> (2) numaral\u0131 enerji denklemlerini birbirine e\u015fitleyip bir tak\u0131m sonu\u00e7lara ula\u015ft\u0131k.\u00a0 Ancak baz\u0131 kolayla\u015ft\u0131rmalar yapt\u0131k, mesela iletken uzunlu\u011fu(L) b\u00fcy\u00fckl\u00fc\u011f\u00fcn\u00fc denklemin her iki taraf\u0131nda oldu\u011fu i\u00e7in g\u00f6t\u00fcrd\u00fck. Sonu\u00e7ta <strong>k<sup>2<\/sup> S<sup>2<\/sup> = I<sup>2<\/sup> t<\/strong>\u00a0 e\u015fitli\u011fine ula\u015ft\u0131k. Bu e\u015fitli\u011fin her iki taraf\u0131 art\u0131k enerji birimi de\u011fildir! Ama enerji hakk\u0131nda fikir veren bir ba\u015fka b\u00fcy\u00fckl\u00fck tan\u0131mlanm\u0131\u015f oluyor : <strong>I<sup>2<\/sup> t<\/strong> . Birimi de A<sup>2<\/sup> s dir.<\/p>\n<p>Yani iletkenlerin hata s\u00fcresince y\u00fcklenebilece\u011fi \u0131s\u0131 enerjisi yerine y\u00fcklenebilece\u011fi <strong>I<sup>2<\/sup> t <\/strong>de\u011feri kullan\u0131l\u0131r<strong>. <\/strong>Yukar\u0131da verilen belli <strong>k<\/strong> de\u011ferleri i\u00e7in belli kesitteki iletkenlerin <strong>I<sup>2<\/sup> t<\/strong> de\u011ferlerini <strong>k<sup>2<\/sup> S<sup>2<\/sup> = I<sup>2<\/sup> t <\/strong>e\u015fitli\u011fini kullanarak bulmak m\u00fcmk\u00fcnd\u00fcr. <em>Bu e\u015fitli\u011fin kullan\u0131m\u0131 5s ve alt\u0131ndaki hata ak\u0131mlar\u0131 i\u00e7in s\u0131n\u0131rland\u0131r\u0131lm\u0131\u015ft\u0131r.<\/em><\/p>\n<h5>\u0130letkenin korunmas\u0131<\/h5>\n<p>Art\u0131k iletkenin limitlerini tam anlam\u0131yla tespit etmi\u015f oluyoruz. Elimizde iletkenin dayanabilece\u011fi azami <strong>I<sup>2<\/sup> t<\/strong> de\u011feri var. Bu de\u011ferin alt\u0131nda kalarak iletkeni korumak, devreyi kesmek gerekir. Hat koruma cihazlar\u0131n\u0131n o hat \u00fczerinden ge\u00e7en hata ak\u0131m\u0131n\u0131, ak\u0131m \u015fiddetinin karesiyle ters orant\u0131l\u0131 bir s\u00fcrede a\u00e7mak zorundad\u0131r. Tasar\u0131m s\u0131ras\u0131nda bu ko\u015fulun sa\u011flan\u0131p sa\u011flanmad\u0131\u011f\u0131 mutlaka kontrol edilmelidir. E\u011fer sa\u011flanm\u0131yorsa devre kesici de\u011fi\u015ftirilmeli, o da olmuyorsa iletken kesit de\u011fi\u015fikli\u011fi yaparak yeni bir <strong>I<sup>2<\/sup> t<\/strong> de\u011feri ko\u015fulunu sa\u011flayamaya \u00e7al\u0131\u015f\u0131lmal\u0131d\u0131r.<\/p>\n<p>Geldi\u011fimiz noktada devre koruyucular\u0131n art\u0131k \u00e7al\u0131\u015fma e\u011frilerini incelemek \u00f6nem kazanmaktad\u0131r. \u00c7\u00fcnk\u00fc hata an\u0131nda, hata ak\u0131m\u0131n\u0131n \u015fiddetine ba\u011fl\u0131 olarak devre kesicinin ne kadar s\u00fcrede a\u00e7aca\u011f\u0131n\u0131 ancak ak\u0131m-zaman e\u011frisine bakarak g\u00f6rebiliriz. Topraklamalar y\u00f6netmeli\u011finde devre kesicilerin izin verilen azami a\u00e7ma s\u00fcreleri verilmi\u015ftir:<\/p>\n<p>Faz-Toprak gerilimi 230V olan <strong>TN sistemlerde<\/strong> (\u00dclkemizde kullan\u0131lan) a\u00e7ma s\u00fcresi 0,4 saniyedir. Bu s\u00fcre,<em> -y\u00f6netmelikte verilen baz\u0131 ko\u015fullar\u0131n sa\u011flanmas\u0131 kayd\u0131yla-<\/em> sabit donan\u0131m\u0131 besleyen devrelerde azami 5 saniye olabilir. <strong>5 saniye<\/strong> kablolar\u0131n, <strong>ekipmanlar\u0131n korumas\u0131<\/strong>nda dikkate al\u0131nabilecek bir s\u00fcredir, <strong>0,4 saniye<\/strong> ise insanlar\u0131n, <strong>canl\u0131lar\u0131n korunmas\u0131<\/strong> i\u00e7in izin verilen s\u00fcredir. <strong>TT sistem<\/strong>lerde bu s\u00fcre <strong>0,2 saniye<\/strong>dir.<strong> IT sistemler<\/strong>de n\u00f6tr\u00fc da\u011f\u0131t\u0131lmam\u0131\u015f ise <strong>0,4 saniye<\/strong>, n\u00f6tr\u00fc da\u011f\u0131t\u0131lm\u0131\u015f ise <strong>0,8 saniye<\/strong>dir.<\/p>\n<p>&nbsp;<\/p>\n<h5>Excel ile hata ak\u0131m\u0131n\u0131n sigorta e\u011frisi \u00fczerinde g\u00f6sterilmesi<\/h5>\n<p>Buraya kadar anlat\u0131lanlar\u0131 a\u015fa\u011f\u0131daki excel tablosunu kullanarak online olarak yapabilirsiniz.<\/p>\n<p><strong><em>(Excelin online versiyonu, masa\u00fcst\u00fc versiyonu kadar \u00e7ok fonksiyonlu de\u011fildir. Bu nedenle sigorta e\u011frilerini al\u0131\u015f\u0131k oldu\u011fumuzun tersine yan olarak \u00e7izmek durumunda kald\u0131k.)<\/em><\/strong><\/p>\n<p>\u0130lk b\u00f6l\u00fcmde, iletkenin \u00f6zelliklerini ve s\u0131n\u0131r s\u0131cakl\u0131klar\u0131n\u0131 se\u00e7erek k de\u011ferini ve k2s2 de\u011ferini tespit ediniz.<\/p>\n<p>\u0130kinci b\u00f6l\u00fcmde kullan\u0131lacak sigorta tipini ve amperaj\u0131n\u0131 a\u00e7\u0131l\u0131r listeden se\u00e7iniz. Hesaplad\u0131\u011f\u0131n\u0131z hata ak\u0131m\u0131n\u0131 ilgili h\u00fccreye giriniz. (Hata ak\u0131m\u0131n\u0131n hesaplanmas\u0131 bu yaz\u0131n\u0131n konusu olmad\u0131\u011f\u0131 i\u00e7in hesap y\u00f6ntemine girilmemi\u015ftir.)<\/p>\n<p>Grafikten hata ak\u0131m\u0131 ile sigorta e\u011frisinin durumu g\u00f6r\u00fclecek, a\u00e7ma zaman\u0131 tespit edilecektir. k2s2&gt;I2t ko\u015fuluna bak\u0131larak iletkenin korunup korunmad\u0131\u011f\u0131 tespit edilecektir.<\/p>\n<p>&nbsp;<\/p>\n<p style=\"text-align: center;\"><iframe loading=\"lazy\" src=\"https:\/\/onedrive.live.com\/embed?resid=5E384BA25F057C18%21125&amp;authkey=%21AJPzn5MIttgHYOI&amp;em=2&amp;wdAllowInteractivity=False&amp;AllowTyping=True&amp;Item='Chart'!N3%3AW57&amp;wdHideGridlines=True&amp;wdDownloadButton=True&amp;wdInConfigurator=True\" width=\"600\" height=\"1150\" frameborder=\"0\" scrolling=\"no\"><\/iframe><\/p>\n<p>&nbsp;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u0130letkenler ister bak\u0131r olsun ister al\u00fcminyum olsun asl\u0131nda, ergime s\u0131cakl\u0131\u011f\u0131n\u0131n alt\u0131nda oldu\u011fu s\u00fcrece, y\u00fczlerce derece s\u0131cakl\u0131klarda y\u00fcklenebilirler. Ama ger\u00e7ekte bunu uygulamak m\u00fcmk\u00fcn olmamaktad\u0131r \u00e7\u00fcnk\u00fc gerek \u0131s\u0131l gerekse elektriksel anlamda iletkenleri yal\u0131tmak durumunday\u0131z. Yal\u0131t\u0131m malzemeleri ise bak\u0131r, al\u00fcminyum metallerinin aksine olduk\u00e7a d\u00fc\u015f\u00fck s\u0131cakl\u0131klara dayanabilmektedir. Yayg\u0131n 2 t\u00fcr yal\u0131t\u0131mdan biri olan thermoplastic (PVC) yal\u0131t\u0131m 70\u00baC s\u0131cakl\u0131\u011fa kadar,&hellip;&nbsp;<a href=\"https:\/\/benga.pro\/index.php\/2020\/02\/29\/kablo-ve-iletkenlerin-korunmasi\/\" rel=\"bookmark\"><span class=\"screen-reader-text\">Kablo ve \u0130letkenlerin Korunmas\u0131<\/span><\/a><\/p>\n","protected":false},"author":3,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"neve_meta_sidebar":"","neve_meta_container":"","neve_meta_enable_content_width":"","neve_meta_content_width":0,"neve_meta_title_alignment":"","neve_meta_author_avatar":"","neve_post_elements_order":"","neve_meta_disable_header":"","neve_meta_disable_footer":"","neve_meta_disable_title":"","_themeisle_gutenberg_block_has_review":false,"footnotes":""},"categories":[5,49],"tags":[267,268,269,270,61,271,272,273],"class_list":["post-3855","post","type-post","status-publish","format-standard","hentry","category-elektrik-tesisat","category-teknik-konular","tag-acma-zamani","tag-hata-akimi","tag-i2t","tag-k2s2","tag-kablo","tag-kesici","tag-sigorta","tag-sigorta-egrisi"],"_links":{"self":[{"href":"https:\/\/benga.pro\/index.php\/wp-json\/wp\/v2\/posts\/3855","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/benga.pro\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/benga.pro\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/benga.pro\/index.php\/wp-json\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/benga.pro\/index.php\/wp-json\/wp\/v2\/comments?post=3855"}],"version-history":[{"count":0,"href":"https:\/\/benga.pro\/index.php\/wp-json\/wp\/v2\/posts\/3855\/revisions"}],"wp:attachment":[{"href":"https:\/\/benga.pro\/index.php\/wp-json\/wp\/v2\/media?parent=3855"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/benga.pro\/index.php\/wp-json\/wp\/v2\/categories?post=3855"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/benga.pro\/index.php\/wp-json\/wp\/v2\/tags?post=3855"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}