Convertor 12-230 V

<div class="separator" style="clear: both; text-align: center;"> <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj6pmPHqEYLrTm4Nz3H_p742WUfcyjWTh8hC7bi5-n63lHg8F5PoAlgli7q328EHVulVLl0etb071d_FNJkoxyN-Kxdu47Yp6eHTHLR6ezQOYWgnQpwChCqC8AIXTkXmScSofAsznYDL04/s1600/convertor.gif" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="491" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj6pmPHqEYLrTm4Nz3H_p742WUfcyjWTh8hC7bi5-n63lHg8F5PoAlgli7q328EHVulVLl0etb071d_FNJkoxyN-Kxdu47Yp6eHTHLR6ezQOYWgnQpwChCqC8AIXTkXmScSofAsznYDL04/s640/convertor.gif" width="640" /></a></div> <br />

Convertor 12-230 V

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Descarcatorul cu oxid de zinc

<div style="background-color: white; text-align: justify;"> <span style="font-family: Arial, Helvetica, sans-serif;">Protectia la supratensiune este foarte importanta, atunci cand se urmareste imbunatatirea calitatii energiei electrice furnizate si siguranta retelei de distributie.<br /> </span></div> <div style="background-color: white; text-align: justify;"> <span style="font-family: Arial, Helvetica, sans-serif;">Protectia adecvata cu descarcatori mareste calitatea alimentarii cu energie electrica si minimizeaza pierderile datorate nefunctionarii retelelor de distributie.</span></div> <div style="background-color: white; text-align: justify;"> <a href="http://www.energoelectric.ro/images/produse/2.5.5/1-t.jpg" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" src="http://www.energoelectric.ro/images/produse/2.5.5/1-t.jpg" /></a><span style="font-family: Arial, Helvetica, sans-serif;"><br /><strong>Caracteristici principale</strong><br />Tensiuni de pana la 36 kV<br />Pana la zona 4 de poluare<br />Curent nominal de descarcare: 5 & 10 kA<br />Tehnologie fara goluri si fara volum intern de gaz<br />Carcasa din cauciuc siliconic de calitate superioara<br /><br /><strong>Beneficii :</strong><br />Continuitatea alimentarii cu energie electrica<br />Tensiune reziduala redusa<br />Linie de fuga de peste 31 mm<br />Siguranta echipamentelor, personalului de exploatare si a publicului<br />Greutate redusaCalitate superioara a energiei furnizate<br />Disponibil cu suporti de montare pe orice tip de stalp MT<br />Fara intretinere<br />Durata de viata crescuta<br />Tensiune reziduala redusa<br />Greutate redusa<br />Simplitate in instalare</span></div>

Descarcatorul cu oxid de zinc

Protectia la supratensiune este foarte importanta, atunci cand se urmareste imbunatatirea calitatii energiei electrice furnizate si siguranta retelei de distributie.  Protectia adecvata cu descarcato…

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Scurtcircuitul monofazat, bifazat si trifazat

<div align="left" class="MsoTitle" style="background-color: white; color: #171717; font-family: verdana; font-size: 12px;"> <b><span lang="RO" style="font-family: 'Times New Roman'; font-size: 14pt;">CALCULUL CURENTILOR DE SCURTCIRCUIT</span></b></div> <div class="MsoNormal" style="background-color: white; color: #171717; font-family: verdana; font-size: 12px; text-align: justify;"> <span lang="RO" style="font-family: 'Times New Roman'; font-size: 16pt;"></span></div> <div align="left" class="MsoBodyText3" style="background-color: white; color: #171717; font-family: verdana; font-size: 12px;"> <br /></div> <div class="MsoNormal" style="background-color: white; color: #171717; font-family: verdana; font-size: 12px; text-align: justify;"> <span lang="RO" style="font-family: 'Times New Roman'; font-size: 12pt;"></span></div> <div class="MsoNormal" style="background-color: white; text-align: justify;"> <span lang="RO" style="color: #171717; font-family: 'Times New Roman'; font-size: 16pt;">      </span><span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO">  </span><span lang="RO">Prin <i>scurtcircuit</i> se intelege contactul accidental,  a doua sau mai multe conductoare, aflate la potentiale electrice diferite.</span></span></div> <div class="MsoNormal" style="background-color: white; text-align: justify;"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">     </span></span><span style="font-family: Arial, Helvetica, sans-serif;">Curentii de scurtcircuit produc in instalatiile electrice urmatoarele efecte:</span></div> <div class="MsoNormal" style="background-color: white; text-align: justify;"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">            - termice, care conduc la incalzirea puternica a conductelor, a contactelor si a altor parti conductoare ale aparatelor, a infasurarilor transformatoarelor si prin aceasta la d 646h74g istrugerea izolatiei, la arderea si eventual sudarea contactelor aparatelor de comutatie;</span></span></div> <div class="MsoNormal" style="background-color: white; text-align: justify;"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">            - dinamice (mecanice), datorate efectului electrodinamic al curentilor, care duc la indoirea barelor, deteriorarea aparatelor, bobinelor etc</span></span></div> <div class="MsoNormal" style="background-color: white; text-align: justify;"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">. </span></span></div> <div class="MsoNormal" style="background-color: white; text-align: justify; text-indent: 35.4pt;"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">Valoarea curentilor de scurtcircuit depinde de:</span></span></div> <div class="MsoNormal" style="background-color: white; margin: 0in 0in 0.0001pt 1in; text-align: justify; text-indent: -0.25in;"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO">·<span style="font-stretch: normal;">       </span></span><span lang="RO">tensiunea, puterea si numarul surselor care alimenteaza scurtcircuitul;</span></span></div> <div class="MsoNormal" style="background-color: white; margin: 0in 0in 0.0001pt 1in; text-align: justify; text-indent: -0.25in;"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO">·<span style="font-stretch: normal;">       </span></span><span lang="RO">distanta dintre surse si locul de scurtcircuit, adica impedanta echivalenta a circuitului cuprins intre sursa si locul scurtcircuitului;</span></span></div> <div align="left" class="MsoBodyText2" style="background-color: white; margin-left: 1in; text-indent: -0.25in;"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO">·<span style="font-stretch: normal;">       </span></span><span lang="RO">momentul producerii scurtcircuitului si timpul scurs din momentul producerii scurtcircuitului.</span></span></div> <div class="MsoNormal" style="background-color: white; text-align: justify;"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">           </span></span></div> <div class="MsoNormal" style="background-color: white; text-align: justify; text-indent: 35.4pt;"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">În instalatiile de curent alternativ trifazat pot avea loc patru tipuri de scurtcircuite:</span></span></div> <div class="MsoNormal" style="background-color: white; margin: 0in 0in 0.0001pt 1in; text-align: justify; text-indent: -0.25in;"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO">·<span style="font-stretch: normal;">      <b><i> </i></b></span></span><span lang="RO"><b><i>scurtcircuitul trifazat;</i></b></span></span></div> <div class="MsoNormal" style="background-color: white; margin: 0in 0in 0.0001pt 1in; text-align: justify; text-indent: -0.25in;"> <span style="font-family: Arial, Helvetica, sans-serif;"><b><i><span lang="RO">·<span style="font-stretch: normal;">       </span></span><span lang="RO">scurtcircuitul bifazat;</span></i></b></span></div> <div class="MsoNormal" style="background-color: white; margin: 0in 0in 0.0001pt 1in; text-align: justify; text-indent: -0.25in;"> <span style="font-family: Arial, Helvetica, sans-serif;"><b><i><span lang="RO">·<span style="font-stretch: normal;">       </span></span><span lang="RO">scurtcircuitul bifazat cu punere la pamant;</span></i></b></span></div> <div class="MsoNormal" style="background-color: white; margin: 0in 0in 0.0001pt 1in; text-align: justify; text-indent: -0.25in;"> <span style="font-family: Arial, Helvetica, sans-serif;"><b><i><span lang="RO">·<span style="font-stretch: normal;">       </span></span><span lang="RO">scurtcircuitul monofazat.</span></i></b></span></div> <div class="MsoNormal" style="background-color: white; text-align: justify;"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">           </span></span></div> <div align="left" class="MsoBodyTextIndent" style="background-color: white;"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">În tabelul 1 sunt prezentate tipurile de scurtcircuit, care apar in retelele electrice trifazate.</span></span></div> <div class="MsoNormal" style="background-color: white; text-align: justify;"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <h1 align="left" style="background-color: white;"> <span lang="RO" style="font-weight: normal;"><span style="font-family: Arial, Helvetica, sans-serif; font-size: small;">Tabelul 1</span></span></h1> <h2 align="left" style="background-color: white;"> <span lang="RO" style="font-weight: normal;"><span style="font-family: Arial, Helvetica, sans-serif; font-size: small;">Tipuri de scurtcircuit in retelele electrice</span></span></h2> <div class="MsoNormal" style="background-color: white; text-align: justify;"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div align="center" style="background-color: white;"> <table border="1" cellpadding="0" cellspacing="0" class="MsoNormalTable" style="border-collapse: collapse; border: none;"><tbody> <tr><td style="border: 1pt solid black; padding: 0in 5.4pt;" valign="top" width="189"><div class="MsoNormal"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoNormal"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">Tipul scurtcircuitului</span></span></div> <div class="MsoNormal"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> </td><td style="border-bottom-color: black; border-bottom-width: 1pt; border-right-color: black; border-right-width: 1pt; border-style: solid solid solid none; border-top-color: black; border-top-width: 1pt; padding: 0in 5.4pt;" valign="top" width="189"><div class="MsoNormal"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoNormal"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">Simbol curent                           de scurtcircuit</span></span></div> </td><td style="border-bottom-color: black; border-bottom-width: 1pt; border-right-color: black; border-right-width: 1pt; border-style: solid solid solid none; border-top-color: black; border-top-width: 1pt; padding: 0in 5.4pt;" valign="top" width="189"><div class="MsoNormal"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoNormal"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">Probabilitatea de aparitie in %</span></span></div> </td></tr> <tr><td style="border-bottom-color: black; border-bottom-width: 1pt; border-left-color: black; border-left-width: 1pt; border-right-color: black; border-right-width: 1pt; border-style: none solid solid; padding: 0in 5.4pt;" valign="top" width="189"><div class="MsoNormal"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoNormal"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">Trifazat</span></span></div> <div class="MsoNormal"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> </td><td style="border-bottom-color: black; border-bottom-width: 1pt; border-right-color: black; border-right-width: 1pt; border-style: none solid solid none; padding: 0in 5.4pt;" valign="top" width="189"><div class="MsoNormal"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoNormal"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">                 _{<img height="26" src="http://www.rasfoiesc.com/files/electronica/543_poze/image002.gif" v:shapes="_x0000_i1025" width="26" />}</span></span></div> </td><td style="border-bottom-color: black; border-bottom-width: 1pt; border-right-color: black; border-right-width: 1pt; border-style: none solid solid none; padding: 0in 5.4pt;" valign="top" width="189"><div class="MsoNormal"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoNormal"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">5</span></span></div> </td></tr> <tr><td style="border-bottom-color: black; border-bottom-width: 1pt; border-left-color: black; border-left-width: 1pt; border-right-color: black; border-right-width: 1pt; border-style: none solid solid; padding: 0in 5.4pt;" valign="top" width="189"><div class="MsoNormal"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoNormal"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">Bifazat</span></span></div> <div class="MsoNormal"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> </td><td style="border-bottom-color: black; border-bottom-width: 1pt; border-right-color: black; border-right-width: 1pt; border-style: none solid solid none; padding: 0in 5.4pt;" valign="top" width="189"><div class="MsoNormal"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoNormal"> <span lang="RO">_{<span style="font-family: Arial, Helvetica, sans-serif;"><img height="26" src="http://www.rasfoiesc.com/files/electronica/543_poze/image004.gif" v:shapes="_x0000_i1028" width="26" /></span>}</span></div> </td><td style="border-bottom-color: black; border-bottom-width: 1pt; border-right-color: black; border-right-width: 1pt; border-style: none solid solid none; padding: 0in 5.4pt;" valign="top" width="189"><div class="MsoNormal"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoNormal"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">10</span></span></div> </td></tr> <tr><td style="border-bottom-color: black; border-bottom-width: 1pt; border-left-color: black; border-left-width: 1pt; border-right-color: black; border-right-width: 1pt; border-style: none solid solid; padding: 0in 5.4pt;" valign="top" width="189"><div class="MsoNormal"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoNormal"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">Bifazat cu punere la pamant</span></span></div> <div class="MsoNormal"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> </td><td style="border-bottom-color: black; border-bottom-width: 1pt; border-right-color: black; border-right-width: 1pt; border-style: none solid solid none; padding: 0in 5.4pt;" valign="top" width="189"><div class="MsoNormal"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoNormal"> <span lang="RO">_{<span style="font-family: Arial, Helvetica, sans-serif;"><img height="26" src="http://www.rasfoiesc.com/files/electronica/543_poze/image006.gif" v:shapes="_x0000_i1026" width="34" /></span>}</span></div> </td><td style="border-bottom-color: black; border-bottom-width: 1pt; border-right-color: black; border-right-width: 1pt; border-style: none solid solid none; padding: 0in 5.4pt;" valign="top" width="189"><div class="MsoNormal"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoNormal"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">20</span></span></div> </td></tr> <tr><td style="border-bottom-color: black; border-bottom-width: 1pt; border-left-color: black; border-left-width: 1pt; border-right-color: black; border-right-width: 1pt; border-style: none solid solid; padding: 0in 5.4pt;" valign="top" width="189"><div class="MsoNormal"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoNormal"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">Monofazat</span></span></div> <div class="MsoNormal"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> </td><td style="border-bottom-color: black; border-bottom-width: 1pt; border-right-color: black; border-right-width: 1pt; border-style: none solid solid none; padding: 0in 5.4pt;" valign="top" width="189"><div class="MsoNormal"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoNormal"> <span lang="RO">_{<span style="font-family: Arial, Helvetica, sans-serif;"><img height="26" src="http://www.rasfoiesc.com/files/electronica/543_poze/image008.gif" v:shapes="_x0000_i1027" width="24" /></span>}</span></div> </td><td style="border-bottom-color: black; border-bottom-width: 1pt; border-right-color: black; border-right-width: 1pt; border-style: none solid solid none; padding: 0in 5.4pt;" valign="top" width="189"><div class="MsoNormal"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoNormal"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">65</span></span></div> </td></tr> </tbody></table> </div> <div class="MsoNormal" style="background-color: white; text-align: justify;"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoNormal" style="background-color: white; text-align: justify;"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">            Tipul de scurtcircuit care poate sa apara intr-o retea electrica este determinat de modul de tratare a neutrului transformatorului, la care este legata reteaua considerata. Scurtcircuitul monofazat poate apare numai in retelele cu neutrul legat direct la pamant. În retelele cu neutrul izolat, contactul dintre un conductor si pamant poarta denumirea de <i>punere la</i><b></b><i>pamant</i>. La aceste retele scurtcircuitul bifazat cu punere la pamant este de fapt un scurtcircuit bifazat simplu.</span></span></div> <div align="left" class="MsoBodyText2" style="background-color: white;"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">          </span></span></div> <div align="left" class="MsoBodyText2" style="background-color: white;"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">  Calculul curentilor de scurtcircuit este necesar pentru:</span></span></div> <div class="MsoNormal" style="background-color: white; margin: 0in 0in 0.0001pt 1in; text-align: justify; text-indent: -0.25in;"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO">·<span style="font-stretch: normal;">       </span></span><span lang="RO">verificarea elementelor componente ale instalatiilor electrice la stabilitate termica si dinamica;</span></span></div> <div class="MsoNormal" style="background-color: white; margin: 0in 0in 0.0001pt 1in; text-align: justify; text-indent: -0.25in;"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO">·<span style="font-stretch: normal;">       </span></span><span lang="RO">alegerea si reglarea instalatiilor de protectie prin relee si automatizare.</span></span></div> <div class="MsoNormal" style="background-color: white; text-align: justify;"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">            Curentii de scurtcircuit trifazat produc cele mai mari solicitari dinamice si termice. Datorita acestui fapt calculul curentilor de scurt-circuit trifazat serveste la:</span></span></div> <div class="MsoNormal" style="background-color: white; margin: 0in 0in 0.0001pt; text-align: justify; text-indent: 0.75in;"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO">·<span style="font-stretch: normal;">       </span></span><span lang="RO">alegerea aparatajului primar si dimensionarea cailor de curent;</span></span></div> <div class="MsoNormal" style="background-color: white; margin: 0in 0in 0.0001pt 1in; text-align: justify; text-indent: -0.25in;"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO">·<span style="font-stretch: normal;">       </span></span><span lang="RO">verificarea tensiunii remanente pe barele colectoare ale statiilor electrice.</span></span></div> <div class="MsoNormal" style="background-color: white; text-align: justify;"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">            Calculul curentilor, in cazul scurtcircuitelor nesimetrice bi si monofazate, serveste la alegerea si reglarea instalatiilor de protectie prin relee si automatizare si la dimensionarea prizelor de pamant de exploa-tare din cadrul posturilor de transformare.</span></span></div> <div class="MsoNormal" style="background-color: white; text-align: justify;"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">            Valorile curentilor de scurtcircuit sunt aproximativ cu doua ordine de marime mai mari decat ale curentilor nominali.</span></span></div> <div class="MsoNormal" style="background-color: white; text-align: justify;"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">            Din punctul de vedere al „distantei electrice” (impedanta elec-trica) dintre locul in care se produce scurtcircuitul si sursele de tensiune, scurtcircuitele se impart in scurtcircuite „departate” si scurtcircuite „apro-piate”.</span></span></div> <div class="MsoNormal" style="background-color: white; text-align: justify;"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">            Prin <i>scurtcircuit departat</i> se intelege scurtcircuitul la care pon-derea impedantei generatorului sincron este redusa fata de impedanta dintre sursa si locul de scurtcircuit si deci scurtcircuitul se produce „departe” de generator, impedanta de calcul fiind constanta in timp.</span></span></div> <div class="MsoNormal" style="background-color: white; text-align: justify;"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">În cazul <i>scurtcircuitului apropiat</i>, in limitarea curentului de scurtcircuit, o mare pondere o are impedanta generatorului sincron care nu este constanta in timp. Scurtcircuitul este apropiat, daca cel putin un generator electric se afla „aproape” de locul de scurtcircuit.</span></span></div> <div class="MsoNormal" style="background-color: white; text-align: justify;"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;"><br /></span></span></div> <div class="MsoNormal" style="background-color: white; text-align: justify;"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;"> <b>CURENTUL DE SCURTCIRCUIT DEPARTAT</b></span></span></div> <div class="MsoNormal" style="background-color: white; text-align: justify;"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO">        </span><span lang="RO">Regimul de scurtcircuit, intr-o retea, este caracterizat de faptul ca prin disparitia sarcinii active a receptorului, in urma scurtcircuitarii, ramane ca sarcina numai reteaua care are un pronuntat caracter inductiv.</span></span></div> <div class="MsoNormal" style="background-color: white; text-align: justify;"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">            Se poate considera, ca model de calcul pentru curentul de scurt-circuit departat, schema din figura 5.1 in care, in urma scurtcircuitarii sarcinii <i>Z_s</i> , prin deteriorarea izolatiei intre punctele <i>a</i> si <i>b</i>, ramane in circuit rezistenta <i>R</i> si inductanta <i>L</i>.</span></span></div> <div class="MsoNormal" style="background-color: white; text-align: justify;"> <span style="font-family: Arial, Helvetica, sans-serif;"><span style="height: 42px; margin-left: 167px; margin-top: 95px; width: 66px;"></span></span></div> <table cellpadding="0" cellspacing="0" style="background-color: white; text-align: justify;"><tbody> <tr><td bgcolor="white" height="42" style="background-attachment: initial; background-clip: initial; background-image: initial; background-origin: initial; background-position: initial; background-repeat: initial; background-size: initial; border: 0.75pt solid white; vertical-align: top;" width="66"><span style="font-family: Arial, Helvetica, sans-serif;"><span style="z-index: 1;"><table cellpadding="0" cellspacing="0" style="width: %px;"><tbody> <tr><td><div class="shape" style="padding: 4.35pt 7.95pt;" v:shape="_x0000_s1028"> <div class="MsoNormal"> <span lang="RO"></span></div> </div> </td></tr> </tbody></table> </span> </span></td></tr> </tbody></table> <div class="MsoNormal" style="background-color: white; line-height: 18px; text-align: justify; text-indent: 0.5in;"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO" style="line-height: normal; text-indent: 0px;"><img height="121" src="http://www.rasfoiesc.com/files/electronica/543_poze/image010.gif" v:shapes="_x0000_i1029" width="258" /></span><b style="line-height: normal; text-indent: 0px;"><span lang="RO"></span></b></span></div> <div style="background-color: white; text-align: justify;"> </div> <div class="MsoNormal" style="background-color: white; text-align: justify;"> <b><span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></b></div> <div class="MsoNormal" style="background-color: white; text-align: justify;"> <span style="font-family: Arial, Helvetica, sans-serif;"><b><span lang="RO">Fig.5.1</span></b><i><span lang="RO"> </span></i><span lang="RO">Explicativa privind producerea curentului de scurtcircuit.</span><span lang="RO"></span></span></div> <div class="MsoNormal" style="background-color: white; text-align: justify;"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">            Ecuatia diferentiala corespunzatoare regimului tranzitoriu este:</span></span></div> <div class="MsoNormal" style="background-color: white; text-align: justify;"> <span style="font-family: Arial, Helvetica, sans-serif;"><i><span lang="RO">u = R i_sc +L</span></i><span lang="RO"> _{<img height="42" src="http://www.rasfoiesc.com/files/electronica/543_poze/image012.gif" v:shapes="_x0000_i1030" width="30" />} ,                                     </span><span lang="RO">(5.1)</span></span></div> <div class="MsoNormal" style="background-color: white; text-align: justify;"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">in care tensiunea de alimentare are expresia:</span></span></div> <div class="MsoNormal" style="background-color: white; text-align: justify;"> <span style="font-family: Arial, Helvetica, sans-serif;"><i><span lang="RO">u = U</span></i><span lang="RO"> _{<img height="22" src="http://www.rasfoiesc.com/files/electronica/543_poze/image014.gif" v:shapes="_x0000_i1031" width="26" />}sin<i>(</i></span><i><span lang="RO">w</span></i><i><span lang="RO"> t + </span></i><i><span lang="RO">b</span></i><i><span lang="RO">)</span></i><span lang="RO"> .                              </span><span lang="RO">(5.2)</span></span></div> <div class="MsoNormal" style="background-color: white; text-align: justify;"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoNormal" style="background-color: white; text-align: justify;"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">            Solutia acestei ecuatii diferentiale este constituita dintr-o componenta permanenta si una aperiodica (libera).</span></span></div> <div class="MsoNormal" style="background-color: white; text-align: justify;"> <span style="font-family: Arial, Helvetica, sans-serif;"><i><span lang="RO">i_sc(t) = i_p(t) + i_a(t) ,        </span></i><span lang="RO">                            </span><span lang="RO">(5.3)</span></span></div> <div class="MsoNormal" style="background-color: white; text-align: justify;"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoNormal" style="background-color: white; text-align: justify;"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">unde componenta periodica are expresia:</span></span></div> <div class="MsoNormal" style="background-color: white; text-align: justify;"> <span style="font-family: Arial, Helvetica, sans-serif;"><i><span lang="RO">i_p(t) = I_p</span></i><span lang="RO"> _{<img height="22" src="http://www.rasfoiesc.com/files/electronica/543_poze/image014.gif" v:shapes="_x0000_i1032" width="26" />}sin<i>(</i></span><i><span lang="RO">w</span></i><i><span lang="RO"> t + </span></i><i><span lang="RO">b</span></i><i><span lang="RO"> - </span></i><i><span lang="RO">j</span></i><i><span lang="RO"> _sc)</span></i><span lang="RO"> ,                             </span><span lang="RO">(5.4)</span></span></div> <div class="MsoNormal" style="background-color: white; text-align: justify;"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">            În figura 5.2 se prezinta variatia in timp a curentului de scurtcircuit.</span></span></div> <div class="MsoNormal" style="background-color: white; text-align: justify; text-indent: 0.5in;"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">Componenta aperiodica  <i>i_a</i>  scade treptat spre zero, ea amortizan-du-se in timp de circa 0,2 s, in schimb componenta periodica <i>i_p</i> are o am-plitudine constanta.</span></span></div> <div class="MsoNormal" style="background-color: white; text-align: justify;"> <span style="font-family: Arial, Helvetica, sans-serif;"><span style="height: 30px; margin-left: 179px; margin-top: 239px; width: 78px;"></span></span></div> <table cellpadding="0" cellspacing="0" style="background-color: white; text-align: justify;"><tbody> <tr><td bgcolor="white" height="30" style="background-attachment: initial; background-clip: initial; background-image: initial; background-origin: initial; background-position: initial; background-repeat: initial; background-size: initial; border: 0.75pt solid white; vertical-align: top;" width="78"><span style="font-family: Arial, Helvetica, sans-serif;"><span style="z-index: 2;"><table cellpadding="0" cellspacing="0" style="width: %px;"><tbody> <tr><td><div class="shape" style="padding: 4.35pt 7.95pt;" v:shape="_x0000_s1029"> <div class="MsoNormal"> <span lang="RO"></span></div> </div> </td></tr> </tbody></table> </span> </span></td></tr> </tbody></table> <div class="MsoNormal" style="background-color: white; line-height: 18px; text-align: justify; text-indent: 0.5in;"> <span lang="RO" style="line-height: normal; text-indent: 0px;"><span style="font-family: Arial, Helvetica, sans-serif;"><img height="266" src="http://www.rasfoiesc.com/files/electronica/543_poze/image017.gif" v:shapes="_x0000_i1033" width="345" /></span></span></div> <div style="background-color: white; text-align: justify;"> </div> <div class="MsoNormal" style="background-color: white; text-align: justify;"> <span style="font-family: Arial, Helvetica, sans-serif;"><b><span lang="RO">  Fig.5.2</span></b><span lang="RO"> Variatia in timp a curentului de scurtcircuit departat.</span></span></div> <div class="MsoNormal" style="background-color: white; text-align: justify;"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">           </span></span></div> <div class="MsoNormal" style="background-color: white; text-align: justify;"> <span lang="RO"><b><span style="font-family: Arial, Helvetica, sans-serif;">CURENTUL DE SCURTCIRCUIT APROPIAT</span></b></span></div> <div class="MsoBodyText" style="background-color: white; text-align: justify;"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">            În cazul scurtcircuitului apropiat, in limitarea curentului de scurtcircuit o mare pondere o are impedanta generatorului sincron care nu este constanta in timp. În aceasta situatie, cresterea brusca a curentului, in infasurarea statorica a generatorului, duce la cresterea campului magnetic de reactie care are un caracter demagnetizant, avand drept consecinta scaderea valorii efective a tensiunii electromotoare, respectiv scaderea va-lorii efective a componentei periodice a curentului de scurtcircuit. Dar, da-torita inductivitatii infasurarilor de excitatie si de amortizare a gene-ratorului, scaderea tensiunii electromotoare nu se produce brusc, ci in regim tranzitoriu.</span></span></div> <div class="MsoNormal" style="background-color: white; text-align: justify;"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">            În majoritatea cazurilor, generatoarele electrice sunt echipate cu <i>regulatoare automate de tensiune</i> <i>(RAT),</i> destinate sa mentina constanta tensiunea la borne, la valoarea nominala, prin variatia curentului de excitatie.</span></span></div> <div class="MsoNormal" style="background-color: white; text-align: justify;"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">            Regulatoarele automate de tensiune intra in actiune destul de repede, dupa 0,2 – 0,3 secunde de la producerea scurtcircuitului, incat valoarea efectiva a componentei periodice a curentului creste din nou, pana la valoarea corespunzatoare regimului de scurtcircuit stabilizat.       </span></span></div> <div class="MsoNormal" style="background-color: white; text-align: justify; text-indent: 0.5in;"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">În figura 5.3 este aratata variatia curentului de scurtcircuit apropiat, alimentat de un generator electric sincron prevazut cu regulator auto-mat de tensiune.</span></span></div> <div class="MsoNormal" style="background-color: white; text-align: justify; text-indent: 0.5in;"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoNormal" style="background-color: white; text-align: justify;"> <span style="font-family: Arial, Helvetica, sans-serif;"><span style="height: 30px; margin-left: 179px; margin-top: 222px; width: 66px;"></span></span></div> <table cellpadding="0" cellspacing="0" style="background-color: white; text-align: justify;"><tbody> <tr><td bgcolor="white" height="30" style="background-attachment: initial; background-clip: initial; background-image: initial; background-origin: initial; background-position: initial; background-repeat: initial; background-size: initial; border: 0.75pt solid white; vertical-align: top;" width="66"><span style="font-family: Arial, Helvetica, sans-serif;"><span style="z-index: 3;"><table cellpadding="0" cellspacing="0" style="width: %px;"><tbody> <tr><td><div class="shape" style="padding: 4.35pt 7.95pt;" v:shape="_x0000_s1030"> <div class="MsoNormal"> <span lang="RO"></span></div> </div> </td></tr> </tbody></table> </span> </span></td></tr> </tbody></table> <div class="MsoNormal" style="background-color: white; line-height: 18px; text-align: justify; text-indent: 0.5in;"> <span lang="RO" style="line-height: normal; text-indent: 0px;"><span style="font-family: Arial, Helvetica, sans-serif;"><img height="248" src="http://www.rasfoiesc.com/files/electronica/543_poze/image019.gif" v:shapes="_x0000_i1034" width="409" /></span></span></div> <div style="background-color: white; text-align: justify;"> </div> <div class="MsoNormal" style="background-color: white; text-align: justify;"> <span style="font-family: Arial, Helvetica, sans-serif;"><b><span lang="RO">Fig. 5.3</span></b><span lang="RO"> Variatia curentului de scurtcircuit apropiat produs de generatoare prevazute cu</span></span></div> <div class="MsoNormal" style="background-color: white; text-align: justify;"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">              regulator automat de tensiune.</span></span></div> <div class="MsoNormal" style="background-color: white; text-align: justify;"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoNormal" style="background-color: white; text-align: justify;"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">            Componenta aperiodica a curentului se anuleaza dupa circa 0,2 s, iar <i>regimul tranzitoriu de scurtcircuit</i> dureaza in total 3 – 5 s. Rezulta ca regulatorul automat de tensiune intra in functiune dupa anularea compo-nentei aperiodice si deci,<i>regimul subtranzitoriu</i> (regimul tranzitoriu de scurtcircuit in care componenta aperiodica este diferita de zero) nu este modificat de <i>RAT</i>.</span></span></div> <div class="MsoBodyText" style="background-color: white; text-align: justify;"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">         METODA DIRECTA DE CALCUL A CURENTULUI DE</span></span></div> <div class="MsoBodyText" style="background-color: white; text-align: justify;"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">         SCURTCIRCUIT TRIFAZAT ÎN RETELELE DE JOASA</span></span></div> <div class="MsoBodyText" style="background-color: white; text-align: justify;"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">         TENSIUNE</span></span></div> <div class="MsoBodyText" style="background-color: white; text-align: justify; text-indent: 0.5in;"> <b><span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></b></div> <div class="MsoBodyText" style="background-color: white; text-align: justify; text-indent: 0.5in;"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">Calculul curentilor de scurtcircuit, in retelele de joasa tensiune, prezinta anumite particularitati. În primul rand, nu se mai pot neglija valorile rezistentelor, in raport cu cele ale reactantelor, intrucat ele pot fi de acelasi ordin de marime. În al doilea rand, retelele de joasa tensiune fiind alimentate, de regula, din retele cu tensiuni superioare prin mai multe trepte de transformare (exceptie fac retelele alimentate de grupuri locale motor- generator), scurtcircuitele care apar pot fi considerate suficient de indepartate de sursele de energie electrica, incat valoarea efectiva a componentei periodice a curentului de scurtcircuit este constanta in timp.</span></span></div> <div class="MsoBodyText" style="background-color: white; text-align: justify; text-indent: 0.5in;"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">Tensiunea de calcul se ia egala cu tensiunea nominala a secundarului transformatorului din postul de transformare, iar rezistentele si reactantele diferitelor elemente de retea se raporteaza la tensiunea de calcul cu ajutorul relatiilor:</span></span></div> <div class="MsoBodyText" style="background-color: white; text-align: justify; text-indent: 0.5in;"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoBodyText" style="background-color: white; text-align: justify; text-indent: 0.5in;"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">_{<img height="48" src="http://www.rasfoiesc.com/files/electronica/543_poze/image021.gif" v:shapes="_x0000_i1035" width="194" />}                             (5.75)</span></span></div> <div class="MsoBodyText" style="background-color: white; text-align: justify; text-indent: 0.5in;"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoBodyText" style="background-color: white; text-align: justify;"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO">unde <i>U_n</i> este tensiunea nominala a secundarului transformatorului, <i>U_n</i></span><i>_{<span lang="RO">l</span>}</i><i><span lang="RO"> </span></i><span lang="RO">- tensiunea nominala a portiunii de retea din care face parte elementul considerat.</span></span></div> <div class="MsoBodyText" style="background-color: white; text-align: justify; text-indent: 0.5in;"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">Relatiile de raportare (5.75) s-au obtinut din conditia de conservare a puterilor activa si reactiva pe cele doua niveluri de tensiune.</span></span></div> <div class="MsoBodyText" style="background-color: white; text-align: justify; text-indent: 0.5in;"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">În urma transfigurarilor succesive ale schemei electrice transpuse in complex se obtine rezistenta echivalenta _{<img height="22" src="http://www.rasfoiesc.com/files/electronica/543_poze/image023.gif" v:shapes="_x0000_i1036" width="22" />}si reactanta echivalenta _{<img height="22" src="http://www.rasfoiesc.com/files/electronica/543_poze/image025.gif" v:shapes="_x0000_i1037" width="24" />}, in care o mare pondere o are reactanta transformatorului.</span></span></div> <div class="MsoBodyText" style="background-color: white; text-align: justify; text-indent: 0.5in;"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">Curentul de scurtcircuit trifazat se calculeaza cu relatia:</span></span></div> <div class="MsoBodyText" style="background-color: white; text-align: justify; text-indent: 0.5in;"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoBodyText" style="background-color: white; text-align: justify; text-indent: 0.5in;"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO">_{<img height="52" src="http://www.rasfoiesc.com/files/electronica/543_poze/image027.gif" v:shapes="_x0000_i1038" width="166" />}.                     </span><span lang="RO">(5.76)</span></span></div> <div class="MsoBodyText" style="background-color: white; text-align: justify; text-indent: 0.5in;"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoBodyText" style="background-color: white; text-align: justify; text-indent: 0.5in;"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">La curentul de soc calculat cu relatia (5.14),</span></span></div> <div class="MsoBodyText" style="background-color: white; text-align: justify; text-indent: 0.5in;"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoBodyText" style="background-color: white; text-align: justify; text-indent: 0.5in;"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO">_{<img height="28" src="http://www.rasfoiesc.com/files/electronica/543_poze/image029.gif" v:shapes="_x0000_i1039" width="104" />}                                       </span><span lang="RO">(5.77)</span></span></div> <div class="MsoBodyText" style="background-color: white; text-align: justify; text-indent: 0.5in;"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoBodyText" style="background-color: white; text-align: justify;"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">trebuie luat in considerare si aportul motoarelor electrice asincrone, daca este indeplinita conditia:</span></span></div> <div class="MsoBodyText" style="background-color: white; text-align: justify;"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO">_{<img height="46" src="http://www.rasfoiesc.com/files/electronica/543_poze/image031.gif" v:shapes="_x0000_i1040" width="98" />},                                      </span><span lang="RO">(5.78)</span></span></div> <div class="MsoBodyText" style="background-color: white; text-align: justify;"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoBodyText" style="background-color: white; text-align: justify;"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">in care <i>I_ni </i>este curentul nominal al unui motor, iar <i>I_p</i> este valoarea efectiva a componentei periodice a curentului de scurtcircuit.</span></span></div> <div class="MsoBodyText" style="background-color: white; text-align: justify;"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">            Valoarea instantanee maxima a curentului produs de motoarele asincrone se determina cu relatia (5.73).</span></span></div> <div class="MsoBodyText" style="background-color: white; text-align: justify;"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoBodyText" style="background-color: white; text-align: justify;"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">_{<img height="46" src="http://www.rasfoiesc.com/files/electronica/543_poze/image033.gif" v:shapes="_x0000_i1041" width="126" />}.                                </span></span></div> <div class="MsoBodyText" style="background-color: white; text-align: justify;"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoBodyText" style="background-color: white; text-align: justify;"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoBodyText" style="background-color: white; text-align: justify;"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">    </span></span></div> <div class="MsoBodyText" style="background-color: white; text-align: justify; text-indent: 0.5in;"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoBodyText" style="background-color: white; text-align: justify;"> <i><span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></i></div> <div class="MsoBodyText" style="background-color: white; text-align: justify;"> <i><span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></i></div> <div class="MsoBodyText" style="background-color: white; text-align: justify;"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">         <b>ÎNCALZIREA CONDUCTOARELOR ÎN REGIM DE</b></span></span></div> <div class="MsoBodyText" style="background-color: white; text-align: justify;"> <span lang="RO"><b><span style="font-family: Arial, Helvetica, sans-serif;">         SCURTCIRCUIT</span></b></span></div> <div class="MsoBodyText" style="background-color: white; text-align: justify;"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoBodyText" style="background-color: white; text-align: justify;"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">            Datorita duratei reduse a scurtcircuitului, respectiv a incalzirii, se poate neglija caldura evacuata, adica se poate considera ca intreaga caldura dezvoltata, datorita curentului de scurtcircuit, se inmagazineaza in conductor (procesul termic este adiabatic).</span></span></div> <div class="MsoBodyText" style="background-color: white; text-align: justify; text-indent: 0.5in;"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">Bilantul termic, pentru un timp infinit de mic <i>dt</i>, este descris de ecuatia diferentiala:</span></span></div> <div class="MsoBodyText" style="background-color: white; text-align: justify;"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO">                        <i>p dt =c M d</i></span><i><span lang="RO">q</span></i><i><span lang="RO">,</span></i><span lang="RO">                                                           </span><span lang="RO">(5.134)</span></span></div> <div class="MsoBodyText" style="background-color: white; text-align: justify;"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoBodyText" style="background-color: white; text-align: justify;"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">unde  <i>p</i> este caldura dezvoltata in unitatea de timp datorita efectului elec-trocaloric al curentului electric;</span></span></div> <div class="MsoBodyText" style="background-color: white; text-align: justify;"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">         <i>c</i> – caldura specifica a conductorului;</span></span></div> <div class="MsoBodyText" style="background-color: white; text-align: justify;"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">         <i>M</i> – masa conductorului;</span></span></div> <div class="MsoBodyText" style="background-color: white; text-align: justify;"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO">        </span><i><span lang="RO">q</span></i><span lang="RO"> – supratemperatura (diferenta dintre temperatura conductorului si temperatura mediului ambiant).</span></span></div> <div class="MsoBodyText" style="background-color: white; text-align: justify;"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO">            Se obtine supratemperatura finala </span><i><span lang="RO">q</span></i><i>_{<span lang="RO">f</span>}</i><span lang="RO">.</span><i><span lang="RO"></span></i></span></div> <div class="MsoBodyText" style="background-color: white; text-align: justify;"> <i><span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">Tabelul 5.4</span></span></i></div> <div align="center" style="background-color: white;"> <table border="1" cellpadding="0" cellspacing="0" class="MsoNormalTable" style="border-collapse: collapse; border: none; margin-left: 5.4pt;"><tbody> <tr><td style="border: 1pt solid windowtext; padding: 0in 5.4pt;" valign="top" width="85"><div class="MsoBodyText"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoBodyText"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">Materialul</span></span></div> <div class="MsoBodyText"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> </td><td style="border-bottom-color: windowtext; border-bottom-width: 1pt; border-right-color: windowtext; border-right-width: 1pt; border-style: solid solid solid none; border-top-color: windowtext; border-top-width: 1pt; padding: 0in 5.4pt;" valign="top" width="94"><div class="MsoBodyText"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoBodyText"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO">g</span><span lang="RO"></span></span></div> <div class="MsoBodyText"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">[kg/m³]</span></span></div> </td><td style="border-bottom-color: windowtext; border-bottom-width: 1pt; border-right-color: windowtext; border-right-width: 1pt; border-style: solid solid solid none; border-top-color: windowtext; border-top-width: 1pt; padding: 0in 5.4pt;" valign="top" width="94"><div class="MsoBodyText"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoBodyText"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">c₀</span></span></div> <div class="MsoBodyText"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">[J/kgK]</span></span></div> </td><td style="border-bottom-color: windowtext; border-bottom-width: 1pt; border-right-color: windowtext; border-right-width: 1pt; border-style: solid solid solid none; border-top-color: windowtext; border-top-width: 1pt; padding: 0in 5.4pt;" valign="top" width="94"><div class="MsoBodyText"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoBodyText"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO">r</span>_{<span lang="RO">0</span>}</span></div> <div class="MsoBodyText"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO">[</span><span lang="RO">W</span><span lang="RO"> m]</span></span></div> </td><td style="border-bottom-color: windowtext; border-bottom-width: 1pt; border-right-color: windowtext; border-right-width: 1pt; border-style: solid solid solid none; border-top-color: windowtext; border-top-width: 1pt; padding: 0in 5.4pt;" valign="top" width="94"><div class="MsoBodyText"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoBodyText"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO">a</span>_{<span lang="RO">c</span>}</span></div> <div class="MsoBodyText"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">[⁰C^-1]</span></span></div> </td><td style="border-bottom-color: windowtext; border-bottom-width: 1pt; border-right-color: windowtext; border-right-width: 1pt; border-style: solid solid solid none; border-top-color: windowtext; border-top-width: 1pt; padding: 0in 5.4pt;" valign="top" width="77"><div class="MsoBodyText"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoBodyText"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO">a</span>_{<span lang="RO">r</span>}_{<span lang="RO"></span>}</span></div> <div class="MsoBodyText"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">[⁰C^-1]</span></span></div> </td></tr> <tr><td style="border-bottom-color: windowtext; border-bottom-width: 1pt; border-left-color: windowtext; border-left-width: 1pt; border-right-color: windowtext; border-right-width: 1pt; border-style: none solid solid; padding: 0in 5.4pt;" valign="top" width="85"><div class="MsoBodyText"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoBodyText"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">Cupru</span></span></div> <div class="MsoBodyText"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> </td><td style="border-bottom-color: windowtext; border-bottom-width: 1pt; border-right-color: windowtext; border-right-width: 1pt; border-style: none solid solid none; padding: 0in 5.4pt;" valign="top" width="94"><div class="MsoBodyText"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoBodyText"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">8960</span></span></div> </td><td style="border-bottom-color: windowtext; border-bottom-width: 1pt; border-right-color: windowtext; border-right-width: 1pt; border-style: none solid solid none; padding: 0in 5.4pt;" valign="top" width="94"><div class="MsoBodyText"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoBodyText"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">383,0</span></span></div> </td><td style="border-bottom-color: windowtext; border-bottom-width: 1pt; border-right-color: windowtext; border-right-width: 1pt; border-style: none solid solid none; padding: 0in 5.4pt;" valign="top" width="94"><div class="MsoBodyText"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoBodyText"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">0,0178.10^-6</span></span></div> </td><td style="border-bottom-color: windowtext; border-bottom-width: 1pt; border-right-color: windowtext; border-right-width: 1pt; border-style: none solid solid none; padding: 0in 5.4pt;" valign="top" width="94"><div class="MsoBodyText"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoBodyText"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">2,80838.10^-4</span></span></div> </td><td style="border-bottom-color: windowtext; border-bottom-width: 1pt; border-right-color: windowtext; border-right-width: 1pt; border-style: none solid solid none; padding: 0in 5.4pt;" valign="top" width="77"><div class="MsoBodyText"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoBodyText"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">3,92.10^-3</span></span></div> </td></tr> <tr><td style="border-bottom-color: windowtext; border-bottom-width: 1pt; border-left-color: windowtext; border-left-width: 1pt; border-right-color: windowtext; border-right-width: 1pt; border-style: none solid solid; padding: 0in 5.4pt;" valign="top" width="85"><div class="MsoBodyText"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoBodyText"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">Aluminiu</span></span></div> <div class="MsoBodyText"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> </td><td style="border-bottom-color: windowtext; border-bottom-width: 1pt; border-right-color: windowtext; border-right-width: 1pt; border-style: none solid solid none; padding: 0in 5.4pt;" valign="top" width="94"><div class="MsoBodyText"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoBodyText"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">2700</span></span></div> </td><td style="border-bottom-color: windowtext; border-bottom-width: 1pt; border-right-color: windowtext; border-right-width: 1pt; border-style: none solid solid none; padding: 0in 5.4pt;" valign="top" width="94"><div class="MsoBodyText"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoBodyText"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">896,1</span></span></div> </td><td style="border-bottom-color: windowtext; border-bottom-width: 1pt; border-right-color: windowtext; border-right-width: 1pt; border-style: none solid solid none; padding: 0in 5.4pt;" valign="top" width="94"><div class="MsoBodyText"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoBodyText"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">0,029.10^-6</span></span></div> </td><td style="border-bottom-color: windowtext; border-bottom-width: 1pt; border-right-color: windowtext; border-right-width: 1pt; border-style: none solid solid none; padding: 0in 5.4pt;" valign="top" width="94"><div class="MsoBodyText"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoBodyText"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">4,27268.10^-4</span></span></div> </td><td style="border-bottom-color: windowtext; border-bottom-width: 1pt; border-right-color: windowtext; border-right-width: 1pt; border-style: none solid solid none; padding: 0in 5.4pt;" valign="top" width="77"><div class="MsoBodyText"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoBodyText"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">4.10^-3</span></span></div> </td></tr> <tr><td style="border-bottom-color: windowtext; border-bottom-width: 1pt; border-left-color: windowtext; border-left-width: 1pt; border-right-color: windowtext; border-right-width: 1pt; border-style: none solid solid; padding: 0in 5.4pt;" valign="top" width="85"><div class="MsoBodyText"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoBodyText"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">Otel</span></span></div> <div class="MsoBodyText"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> </td><td style="border-bottom-color: windowtext; border-bottom-width: 1pt; border-right-color: windowtext; border-right-width: 1pt; border-style: none solid solid none; padding: 0in 5.4pt;" valign="top" width="94"><div class="MsoBodyText"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoBodyText"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">7700</span></span></div> </td><td style="border-bottom-color: windowtext; border-bottom-width: 1pt; border-right-color: windowtext; border-right-width: 1pt; border-style: none solid solid none; padding: 0in 5.4pt;" valign="top" width="94"><div class="MsoBodyText"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoBodyText"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">459,7</span></span></div> </td><td style="border-bottom-color: windowtext; border-bottom-width: 1pt; border-right-color: windowtext; border-right-width: 1pt; border-style: none solid solid none; padding: 0in 5.4pt;" valign="top" width="94"><div class="MsoBodyText"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoBodyText"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">0,17.10^-6</span></span></div> </td><td style="border-bottom-color: windowtext; border-bottom-width: 1pt; border-right-color: windowtext; border-right-width: 1pt; border-style: none solid solid none; padding: 0in 5.4pt;" valign="top" width="94"><div class="MsoBodyText"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoBodyText"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">4,9483.10^-4</span></span></div> </td><td style="border-bottom-color: windowtext; border-bottom-width: 1pt; border-right-color: windowtext; border-right-width: 1pt; border-style: none solid solid none; padding: 0in 5.4pt;" valign="top" width="77"><div class="MsoBodyText"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoBodyText"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">5,2.10^-3</span></span></div> </td></tr> </tbody></table> </div> <div class="MsoBodyText" style="background-color: white; text-align: justify;"> <b><span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></b></div> <div class="MsoBodyText" style="background-color: white; text-align: justify;"> <b><span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></b></div> <div class="MsoBodyText" style="background-color: white; text-align: justify; text-indent: 0.5in;"> </div> <table align="left" cellpadding="0" cellspacing="0" style="background-color: white; text-align: justify;"><tbody> <tr><td height="0" width="154"></td></tr> <tr><td></td><td><span style="font-family: Arial, Helvetica, sans-serif;"><img alt="" height="264" src="http://www.rasfoiesc.com/files/electronica/543_poze/image088.gif" title="EA" v:shapes="_x0000_s1043" width="429" /></span></td></tr> </tbody></table> <div class="MsoNormal" style="background-color: white; line-height: 18px; text-align: justify; text-indent: 0.5in;"> <span style="font-family: Arial, Helvetica, sans-serif;"><br clear="ALL" style="line-height: normal; text-indent: 0px;" /><b style="line-height: normal; text-indent: 0px;"><span lang="RO"></span></b></span></div> <div style="background-color: white; text-align: justify;"> </div> <div class="MsoBodyText" style="background-color: white; text-align: justify; text-indent: 0.5in;"> <b><span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></b></div> <div class="MsoBodyText" style="background-color: white; text-align: justify; text-indent: 0.5in;"> <span style="font-family: Arial, Helvetica, sans-serif;"><b><span lang="RO">Fig. 5.19</span></b><span lang="RO"> Curbele <i>A =f(</i></span><i><span lang="RO">q</span></i><i><span lang="RO">)</span></i><span lang="RO"> pentru conductoarele din cupru</span><span lang="RO">, </span><span lang="RO">aluminiu si otel.</span></span></div> <div class="MsoBodyText" style="background-color: white; text-align: justify; text-indent: 0.5in;"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoBodyText" style="background-color: white; text-align: justify;"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">            Ca urmare a solicitarii termice de scurta durata, temperaturile admisibile ale conductelor la incalzirea in regim de scurtcircuit sunt mult mai mari decat in alte regimuri de incalzire. Temperaturile admisibile la incalzirea in regim de scurtcircuit sunt prezentate in tabelul 5.5.</span></span></div> <div class="MsoBodyText" style="background-color: white; text-align: justify;"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoBodyText" style="background-color: white; text-align: justify;"> <i><span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">Tabelul 5.5</span></span></i></div> <div class="MsoBodyText" style="background-color: white; text-align: justify;"> <span style="font-family: Arial, Helvetica, sans-serif;"><i><span lang="RO">            </span></i><i><span lang="RO">Valorile temperaturii maxime admise la incalzirea conductelor, in regim de scurtcircuit</span></i></span></div> <div class="MsoBodyText" style="background-color: white; text-align: justify;"> <i><span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></i></div> <div align="center" style="background-color: white;"> <table border="1" cellpadding="0" cellspacing="0" class="MsoNormalTable" style="border-collapse: collapse; border: none;"><tbody> <tr><td style="border: 1pt solid windowtext; padding: 0in 5.4pt;" valign="top" width="309"><div class="MsoBodyText"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoBodyText"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">Tipul si materialul conductei_{<img height="22" src="http://www.rasfoiesc.com/files/electronica/543_poze/image050.gif" v:shapes="_x0000_i1071" width="12" />}</span></span></div> <div class="MsoBodyText"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> </td><td style="border-bottom-color: windowtext; border-bottom-width: 1pt; border-right-color: windowtext; border-right-width: 1pt; border-style: solid solid solid none; border-top-color: windowtext; border-top-width: 1pt; padding: 0in 5.4pt;" valign="top" width="257"><div class="MsoBodyText"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoBodyText"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">Temperatura maxima admisibila,^oC</span></span></div> <div class="MsoBodyText"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> </td></tr> <tr style="height: 25.35pt;"><td style="border-bottom-color: windowtext; border-bottom-width: 1pt; border-left-color: windowtext; border-left-width: 1pt; border-right-color: windowtext; border-right-width: 1pt; border-style: none solid solid; height: 25.35pt; padding: 0in 5.4pt;" valign="top" width="309"><div class="MsoBodyText"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoBodyText"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">Bare din cupru</span></span></div> <div class="MsoBodyText"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> </td><td style="border-bottom-color: windowtext; border-bottom-width: 1pt; border-right-color: windowtext; border-right-width: 1pt; border-style: none solid solid none; height: 25.35pt; padding: 0in 5.4pt;" valign="top" width="257"><div class="MsoBodyText"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoBodyText"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">200</span></span></div> </td></tr> <tr><td style="border-bottom-color: windowtext; border-bottom-width: 1pt; border-left-color: windowtext; border-left-width: 1pt; border-right-color: windowtext; border-right-width: 1pt; border-style: none solid solid; padding: 0in 5.4pt;" valign="top" width="309"><div class="MsoBodyText"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoBodyText"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">Bare din aluminiu</span></span></div> <div class="MsoBodyText"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> </td><td style="border-bottom-color: windowtext; border-bottom-width: 1pt; border-right-color: windowtext; border-right-width: 1pt; border-style: none solid solid none; padding: 0in 5.4pt;" valign="top" width="257"><div class="MsoBodyText"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoBodyText"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">200</span></span></div> </td></tr> <tr><td style="border-bottom-color: windowtext; border-bottom-width: 1pt; border-left-color: windowtext; border-left-width: 1pt; border-right-color: windowtext; border-right-width: 1pt; border-style: none solid solid; padding: 0in 5.4pt;" valign="top" width="309"><div class="MsoBodyText"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoBodyText"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">Bare din otel (fara legatura directa cu aparatele)</span></span></div> <div class="MsoBodyText"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> </td><td style="border-bottom-color: windowtext; border-bottom-width: 1pt; border-right-color: windowtext; border-right-width: 1pt; border-style: none solid solid none; padding: 0in 5.4pt;" valign="top" width="257"><div class="MsoBodyText"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoBodyText"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">400</span></span></div> </td></tr> <tr><td style="border-bottom-color: windowtext; border-bottom-width: 1pt; border-left-color: windowtext; border-left-width: 1pt; border-right-color: windowtext; border-right-width: 1pt; border-style: none solid solid; padding: 0in 5.4pt;" valign="top" width="309"><div class="MsoBodyText"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoBodyText"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">Bare din otel (cu legatura directa cu aparatele)</span></span></div> <div class="MsoBodyText"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> </td><td style="border-bottom-color: windowtext; border-bottom-width: 1pt; border-right-color: windowtext; border-right-width: 1pt; border-style: none solid solid none; padding: 0in 5.4pt;" valign="top" width="257"><div class="MsoBodyText"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoBodyText"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">300</span></span></div> </td></tr> <tr><td style="border-bottom-color: windowtext; border-bottom-width: 1pt; border-left-color: windowtext; border-left-width: 1pt; border-right-color: windowtext; border-right-width: 1pt; border-style: none solid solid; padding: 0in 5.4pt;" valign="top" width="309"><div class="MsoBodyText"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoBodyText"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">Cabluri cu izolatie din hartie</span></span></div> <div class="MsoBodyText"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> </td><td style="border-bottom-color: windowtext; border-bottom-width: 1pt; border-right-color: windowtext; border-right-width: 1pt; border-style: none solid solid none; padding: 0in 5.4pt;" valign="top" width="257"><div class="MsoBodyText"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoBodyText"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">200</span></span></div> </td></tr> <tr><td style="border-bottom-color: windowtext; border-bottom-width: 1pt; border-left-color: windowtext; border-left-width: 1pt; border-right-color: windowtext; border-right-width: 1pt; border-style: none solid solid; padding: 0in 5.4pt;" valign="top" width="309"><div class="MsoBodyText"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoBodyText"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">Cabluri cu izolatie din cauciuc sau PVC</span></span></div> <div class="MsoBodyText"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> </td><td style="border-bottom-color: windowtext; border-bottom-width: 1pt; border-right-color: windowtext; border-right-width: 1pt; border-style: none solid solid none; padding: 0in 5.4pt;" valign="top" width="257"><div class="MsoBodyText"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoBodyText"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">150</span></span></div> </td></tr> <tr><td style="border-bottom-color: windowtext; border-bottom-width: 1pt; border-left-color: windowtext; border-left-width: 1pt; border-right-color: windowtext; border-right-width: 1pt; border-style: none solid solid; padding: 0in 5.4pt;" valign="top" width="309"><div class="MsoBodyText"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoBodyText"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">Cabluri si conductoare cu izolatie de polietilena</span></span></div> <div class="MsoBodyText"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> </td><td style="border-bottom-color: windowtext; border-bottom-width: 1pt; border-right-color: windowtext; border-right-width: 1pt; border-style: none solid solid none; padding: 0in 5.4pt;" valign="top" width="257"><div class="MsoBodyText"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoBodyText"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif;">120</span></span></div> </td></tr> </tbody></table> </div> <div class="MsoBodyText" style="background-color: white; text-align: justify;"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO"></span></span></div> <div class="MsoBodyText" style="background-color: white; text-align: justify;"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO">            </span><span lang="RO">           </span></span></div> <div class="MsoNormal" style="background-color: white; line-height: 18px; text-align: justify; text-indent: 0.5in;"> <i><span lang="RO" style="line-height: 24px;"><b><span style="font-family: Arial, Helvetica, sans-serif;"><br /></span></b></span></i></div> <div class="MsoNormal" style="background-color: white; line-height: 18px; text-align: justify; text-indent: 0.5in;"> <i><span lang="RO" style="line-height: 24px;"><b><span style="font-family: Arial, Helvetica, sans-serif;"><br /></span></b></span></i></div> <div class="MsoNormal" style="background-color: white; line-height: 18px; text-align: justify; text-indent: 0.5in;"> <i><span lang="RO" style="line-height: 24px;"><b><span style="font-family: Arial, Helvetica, sans-serif;"><br /></span></b></span></i></div> <div class="MsoNormal" style="background-color: white; line-height: 18px; text-align: justify; text-indent: 0.5in;"> <i><span lang="RO" style="line-height: 24px;"><b><span style="font-family: Arial, Helvetica, sans-serif;"><br /></span></b></span></i></div> <div class="MsoNormal" style="background-color: white; line-height: 18px; text-align: justify; text-indent: 0.5in;"> <i><span lang="RO" style="line-height: 24px;"><b><span style="font-family: Arial, Helvetica, sans-serif;">Calculul curentilor de scurtcircuit bifazat si monofazat.</span></b></span></i></div> <div class="MsoNormal" style="background-color: white; line-height: 18px; text-align: justify; text-indent: 0.5in;"> <b><span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO" style="line-height: 24px;"></span></span></b></div> <div class="MsoNormal" style="background-color: white; line-height: 18px; text-align: justify; text-indent: 0.5in;"> <span style="font-family: Arial, Helvetica, sans-serif;"><br /></span></div> <div class="MsoNormal" style="background-color: white; line-height: 18px; text-align: justify; text-indent: 0.5in;"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO" style="line-height: 24px;"></span></span></div> <h3 style="background-color: white; margin: 0px; padding: 0px; text-align: justify;"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif; font-size: small;">a) <i>Scurtcircuit bifazat</i></span></span></h3> <div class="MsoNormal" style="background-color: white; line-height: 18px; text-align: justify; text-indent: 0.5in;"> <span style="font-family: Arial, Helvetica, sans-serif;"><u><span lang="RO" style="line-height: 24px;">Curentul initial de scurtcircuit </span></u><span lang="RO" style="line-height: 24px;"> I^'_k2</span></span></div> <div class="MsoNormal" style="background-color: white; line-height: 18px; text-align: justify; text-indent: 0.5in;"> <span lang="RO" style="line-height: 24px;"><span style="font-family: Arial, Helvetica, sans-serif;">Independent de configuratia sistemului, curentul initial de scurtcircuit bifazat se calculeaza cu relatia:</span></span></div> <div class="MsoNormal" style="background-color: white; line-height: 18px; text-align: justify;"> <span lang="RO" style="line-height: 24px;"><span style="font-family: Arial, Helvetica, sans-serif;">            </span></span></div> <div style="background-color: white; text-align: justify;"> <table cellpadding="0" cellspacing="0" hspace="0" style="height: 142px; width: 353px;" vspace="0"><tbody> <tr><td align="left" height="142" style="padding: 12pt;" valign="top"><div style="border: 1pt solid white; padding: 0in;"> <div align="center" class="MsoNormal" style="border: none; line-height: 18px; padding: 0in; text-align: center;"> <span lang="RO" style="line-height: 24px;">_{<span style="font-family: Arial, Helvetica, sans-serif;"><img height="87" src="http://www.qreferat.com/files/constructii/231_poze/image002.gif" v:shapes="_x0000_i1028" width="400" /></span>}</span></div> </div> </td></tr> </tbody></table> </div> <div class="MsoNormal" style="background-color: white; line-height: 18px; text-align: justify;"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO" style="line-height: 24px;"></span></span></div> <div class="MsoNormal" style="background-color: white; line-height: 18px; text-align: justify;"> <span lang="RO" style="line-height: 24px;"><span style="font-family: Arial, Helvetica, sans-serif;">                                                                              </span></span></div> <div class="MsoNormal" style="background-color: white; line-height: 18px; text-align: justify;"> <span lang="RO" style="line-height: 24px;"><span style="font-family: Arial, Helvetica, sans-serif;">                                                                                               </span></span></div> <div class="MsoNormal" style="background-color: white; line-height: 18px; text-align: justify; text-indent: 0.5in;"> <span lang="RO" style="line-height: 24px;"><span style="font-family: Arial, Helvetica, sans-serif;">Raportul    _{<img height="24" src="http://www.qreferat.com/files/constructii/231_poze/image004.gif" v:shapes="_x0000_i1026" width="118" />}                                                                                  </span></span></div> <div class="MsoNormal" style="background-color: white; line-height: 18px; text-align: justify; text-indent: 0.5in;"> <span lang="RO" style="line-height: 24px;"><span style="font-family: Arial, Helvetica, sans-serif;">In cazul unui scurtcircuit departe de sursa, curentul permanent de scurtcircuit si curentul de rupere sunt egali cu I^'_k2.</span></span></div> <div class="MsoNormal" style="background-color: white; line-height: 18px; text-align: justify; text-indent: 1.5in;"> <span lang="RO" style="line-height: 24px;"><span style="font-family: Arial, Helvetica, sans-serif;">I_k2=I_r2=I^'_k2                                                                                                       </span></span></div> <div class="MsoNormal" style="background-color: white; line-height: 18px; text-align: justify;"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO" style="line-height: 24px;"></span></span></div> <div class="MsoNormal" style="background-color: white; line-height: 18px; text-align: justify; text-indent: 0.5in;"> <span style="font-family: Arial, Helvetica, sans-serif;"><u><span lang="RO" style="line-height: 24px;">Curentul de scurtcircuit de soc</span></u><span lang="RO" style="line-height: 24px;"> i_soc2</span></span></div> <div class="MsoNormal" style="background-color: white; line-height: 18px; text-align: justify;"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO" style="line-height: 24px;"></span></span></div> <div class="MsoNormal" style="background-color: white; line-height: 18px; text-align: justify; text-indent: 0.5in;"> <span lang="RO" style="line-height: 24px;"><span style="font-family: Arial, Helvetica, sans-serif;">Curentul de scurtcircuit de soc poate fi exprimat prin:</span></span></div> <div class="MsoNormal" style="background-color: white; line-height: 18px; text-align: justify; text-indent: 1.5in;"> <span lang="RO" style="line-height: 24px;"><span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO">i_soc2 = </span><span lang="RO">c</span><span lang="RO"> ·_{<img height="22" src="http://www.qreferat.com/files/constructii/231_poze/image006.gif" v:shapes="_x0000_i1027" width="26" />}· I^'_k2   </span></span></span></div> <div class="MsoNormal" style="background-color: white; line-height: 18px; text-align: justify; text-indent: 1.5in;"> <span lang="RO" style="line-height: 24px;"><span style="font-family: Arial, Helvetica, sans-serif;">                                                                                             </span></span></div> <div class="MsoNormal" style="background-color: white; line-height: 18px; text-align: justify; text-indent: 0.5in;"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO" style="line-height: 24px;">Factorul </span><span lang="RO" style="line-height: 24px;">c</span><span lang="RO" style="line-height: 24px;"> se calculeaza in functie de configuratia sistemului. Pentru simplificare se poate admite aceeasi valoare ca in cazul scurtcircuitului trifazat.</span></span></div> <h3 align="left" style="background-color: white; font-weight: normal; margin: 0px; padding: 0px;"> <span style="font-family: Arial, Helvetica, sans-serif; font-size: small;"><span lang="RO"></span></span></h3> <h3 align="left" style="background-color: white; margin: 0px; padding: 0px;"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif; font-size: small;">b) <i>Scurtcircuit bifazat cu punere la pamant</i></span></span></h3> <h1 align="left" style="background-color: white; font-weight: normal; line-height: 33px; margin: 0px; padding: 0px; text-indent: 0.5in;"> <b><u><span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif; font-size: small;">Curentii initiali de scurtcircuit</span></span></u></b></h1> <div class="MsoNormal" style="background-color: white; line-height: 18px; text-align: justify;"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO" style="line-height: 24px;"></span></span></div> <div class="MsoNormal" style="background-color: white; line-height: 18px; text-align: justify; text-indent: 0.5in;"> <span lang="RO" style="line-height: 24px;"><span style="font-family: Arial, Helvetica, sans-serif;">Formulele de calcul, pentru ipoteza Z⁺ = Z^- sunt:</span></span></div> <div style="background-color: white; text-align: justify;"> <table cellpadding="0" cellspacing="0" hspace="0" style="height: 154px; width: 405px;" vspace="0"><tbody> <tr><td align="left" height="154" style="padding: 12pt;" valign="top"><div style="border: 1pt solid white; padding: 0in;"> <div align="center" class="MsoNormal" style="border: none; line-height: 18px; padding: 0in; text-align: center;"> <span lang="RO" style="line-height: 24px;">_{<span style="font-family: Arial, Helvetica, sans-serif;"><img height="66" src="http://www.qreferat.com/files/constructii/231_poze/image008.gif" v:shapes="_x0000_i1029" width="220" /></span>}</span></div> </div> </td></tr> </tbody></table> </div> <div class="MsoNormal" style="background-color: white; line-height: 18px; text-align: justify;"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO" style="line-height: 24px;"></span></span></div> <div class="MsoNormal" style="background-color: white; line-height: 18px; text-align: justify; text-indent: 0.5in;"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO" style="line-height: 24px;"></span></span></div> <div class="MsoNormal" style="background-color: white; line-height: 18px; text-align: justify;"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO" style="line-height: 24px;"></span></span></div> <div class="MsoNormal" style="background-color: white; line-height: 18px; text-align: justify;"> <span lang="RO" style="line-height: 24px;"><span style="font-family: Arial, Helvetica, sans-serif;">                                                                       </span></span></div> <div style="background-color: white; text-align: justify;"> <table align="left" cellpadding="0" cellspacing="0" hspace="0" style="height: 139px; width: 341px;" vspace="0"><tbody> <tr><td align="left" height="139" style="padding: 11.9pt;" valign="top"><div style="border: 1pt solid white; padding: 0in;"> <div align="center" class="MsoNormal" style="border: none; line-height: 18px; padding: 0in; text-align: center;"> <span lang="RO" style="line-height: 24px;">_{<span style="font-family: Arial, Helvetica, sans-serif;"><img height="66" src="http://www.qreferat.com/files/constructii/231_poze/image010.gif" v:shapes="_x0000_i1032" width="174" /></span>}</span></div> </div> </td></tr> </tbody></table> </div> <div class="MsoNormal" style="background-color: white; line-height: 18px; text-align: justify;"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO" style="line-height: 24px;"></span></span></div> <div class="MsoNormal" style="background-color: white; line-height: 18px; text-align: justify;"> <span lang="RO" style="line-height: 24px;"><span style="font-family: Arial, Helvetica, sans-serif;">                                                                         </span></span></div> <div class="MsoNormal" style="background-color: white; line-height: 18px; text-align: justify;"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO" style="line-height: 24px;"></span></span></div> <div class="MsoNormal" style="background-color: white; line-height: 18px; text-align: justify;"> <span lang="RO" style="line-height: 24px;"><span style="font-family: Arial, Helvetica, sans-serif;">unde: L₂ si L₃ sunt fazele 2, respectiv 3.</span></span></div> <div class="MsoNormal" style="background-color: white; line-height: 18px; text-align: justify;"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO" style="line-height: 24px;"></span></span></div> <div class="MsoNormal" style="background-color: white; line-height: 18px; text-align: justify;"> <span lang="RO" style="line-height: 24px;"><span style="font-family: Arial, Helvetica, sans-serif;">Curentul initial de scurtcircuit I^'_k2p, la pamant sau la conductoare legate la pamant se calculeaza cu:</span></span></div> <div style="background-color: white; text-align: justify;"> <table cellpadding="0" cellspacing="0" hspace="0" style="height: 115px; width: 495px;" vspace="0"><tbody> <tr><td align="left" height="115" style="padding: 12pt;" valign="top"><div style="border: 1pt solid white; padding: 0in;"> <div align="center" class="MsoNormal" style="border: none; line-height: 18px; padding: 0in; text-align: center;"> <span lang="RO" style="line-height: 24px;">_{<span style="font-family: Arial, Helvetica, sans-serif;"><img height="50" src="http://www.qreferat.com/files/constructii/231_poze/image012.gif" v:shapes="_x0000_i1025" width="134" /></span>}</span></div> </div> </td></tr> </tbody></table> </div> <div class="MsoNormal" style="background-color: white; line-height: 18px; text-align: justify;"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO" style="line-height: 24px;"></span></span></div> <div class="MsoNormal" style="background-color: white; line-height: 18px; text-align: justify;"> <span style="font-family: Arial, Helvetica, sans-serif;"><u><span lang="RO" style="line-height: 24px;">Curentul de scurtcircuit de soc </span></u><span lang="RO" style="line-height: 24px;"> i_{soc 2p}</span></span></div> <div class="MsoNormal" style="background-color: white; line-height: 18px; text-align: justify;"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO" style="line-height: 24px;"></span></span></div> <div class="MsoNormal" style="background-color: white; line-height: 18px; text-align: justify;"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO" style="line-height: 24px;">Nu este necesar sa se calculeze i_{soc 2p} deoarece sau i_soc3 </span><span lang="RO" style="line-height: 24px;">³</span><span lang="RO" style="line-height: 24px;"> i_{soc 2p} sau i_soc1 </span><span lang="RO" style="line-height: 24px;">³</span><span lang="RO" style="line-height: 24px;"> i_soc2p .</span></span></div> <div class="MsoNormal" style="background-color: white; line-height: 18px; text-align: justify; text-indent: 0.5in;"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO" style="line-height: 24px;"></span></span></div> <h3 align="left" style="background-color: white; margin: 0px; padding: 0px;"> <span lang="RO"><span style="font-family: Arial, Helvetica, sans-serif; font-size: small;">c) <i>Scurtcircuit monofazat<span style="font-weight: normal;"><u></u></span></i></span></span></h3> <div class="MsoNormal" style="background-color: white; line-height: 18px; text-align: justify; text-indent: 0.5in;"> <span style="font-family: Arial, Helvetica, sans-serif;"><u><span lang="RO" style="line-height: 24px;">Curentul initial de scurtcircuit</span></u><span lang="RO" style="line-height: 24px;">  I^'_k1 (conform fig.1 si tabel 1) pentru ipoteza Z^- = Z⁺ :</span></span></div> <div style="background-color: white; text-align: justify;"> <table align="left" cellpadding="0" cellspacing="0" hspace="0" style="height: 101px; width: 207px;" vspace="0"><tbody> <tr><td align="left" height="101" style="padding: 11.9pt;" valign="top"><div style="border: 1pt solid white; padding: 0in;"> <div align="center" class="MsoNormal" style="border: none; line-height: 18px; padding: 0in; text-align: center;"> <span lang="RO" style="line-height: 24px;">_{<span style="font-family: Arial, Helvetica, sans-serif;"><img height="50" src="http://www.qreferat.com/files/constructii/231_poze/image014.gif" v:shapes="_x0000_i1031" width="140" /></span>}</span></div> </div> </td></tr> </tbody></table> </div> <div class="MsoNormal" style="background-color: white; line-height: 18px; text-align: justify;"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO" style="line-height: 24px;"></span></span></div> <div align="right" class="MsoNormal" style="background-color: white; line-height: 18px; margin-left: 5in; text-align: right; text-indent: 0.5in;"> <span lang="RO" style="line-height: 24px;"><span style="font-family: Arial, Helvetica, sans-serif;">                                                                 (19)</span></span></div> <div class="MsoNormal" style="background-color: white; line-height: 18px; text-align: justify;"> <span lang="RO" style="line-height: 24px;"><span style="font-family: Arial, Helvetica, sans-serif;">          </span></span></div> <div class="MsoNormal" style="background-color: white; line-height: 18px; text-align: justify; text-indent: 0.5in;"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO" style="line-height: 24px;"></span></span></div> <div class="MsoNormal" style="background-color: white; line-height: 18px; text-align: justify; text-indent: 0.5in;"> <span lang="RO" style="line-height: 24px;"><span style="font-family: Arial, Helvetica, sans-serif;">In caz de scurtcircuit departat de sursa, curentii de scurtcircuit permanent I_k1 si curentul de rupere I^”_k1 sunt egali cu curentul de scurtcircuit initial I^”_k1 (relatiile (4) si (5));</span></span></div> <div class="MsoNormal" style="background-color: white; line-height: 18px; text-align: justify; text-indent: 1in;"> <span lang="RO" style="line-height: 24px;"><span style="font-family: Arial, Helvetica, sans-serif;">I_k1=I_r1=I'_k1                                                                                                               </span></span></div> <div class="MsoNormal" style="background-color: white; line-height: 18px; text-align: justify;"> <span lang="RO" style="line-height: 24px;"><span style="font-family: Arial, Helvetica, sans-serif;">                                   </span></span></div> <div class="MsoNormal" style="background-color: white; line-height: 18px; text-align: justify; text-indent: 0.5in;"> <span style="font-family: Arial, Helvetica, sans-serif;"><u><span lang="RO" style="line-height: 24px;">Curentul de scurtcircuit de soc</span></u><span lang="RO" style="line-height: 24px;">  i_soc1</span></span></div> <div class="MsoNormal" style="background-color: white; line-height: 18px; margin-left: 0.5in; text-align: justify; text-indent: 0.5in;"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO" style="line-height: 24px;">_{<img height="28" src="http://www.qreferat.com/files/constructii/231_poze/image016.gif" v:shapes="_x0000_i1030" width="116" />}</span><span lang="RO" style="line-height: 24px;">                                                                                                         </span></span></div> <div class="MsoNormal" style="background-color: white; line-height: 18px; text-align: justify; text-indent: 0.5in;"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO" style="line-height: 24px;"></span></span></div> <div class="MsoNormal" style="background-color: white; line-height: 18px; text-align: justify; text-indent: 0.5in;"> <span style="font-family: Arial, Helvetica, sans-serif;"><span lang="RO" style="line-height: 24px;">c</span><span lang="RO" style="line-height: 24px;"> se calculeaza conform art.22. (2), in functie de configuratia sistemului. Pentru simplificare se admite sa se ia aceeasi valoare ca in cazul scurtcircuitului trifazat.</span></span></div> <div class="MsoNormal" style="background-color: white; line-height: 18px; text-align: justify;"> <span lang="RO" style="line-height: 24px;"><span style="font-family: Arial, Helvetica, sans-serif;">In figura 6 se prezinta domeniile in care diferitii curenti de scurtcircuit sunt maximi pentru cazul impedantelor Z⁺, Z^-, Z⁰_,in faza.</span></span></div> <div class="MsoNormal" style="background-color: white; color: #171510; font-family: Tahoma; font-size: 12px; line-height: 18px; text-align: justify;"> <span lang="RO" style="font-size: 12pt; line-height: 24px;"></span></div> <div class="MsoNormal" style="background-color: white; color: #171510; font-family: Tahoma; font-size: 12px; line-height: 18px; text-align: justify; text-indent: 0.5in;"> <span lang="RO" style="font-size: 12pt; line-height: 24px;"></span></div> <div class="MsoNormal" style="background-color: white; color: #171510; font-family: Tahoma; font-size: 12px; line-height: 18px; text-align: justify; text-indent: 0.5in;"> <span lang="RO" style="font-size: 12pt; line-height: 24px;"></span></div> <div class="MsoNormal" style="background-color: white; color: #171510; font-family: Tahoma; font-size: 12px; line-height: 18px; text-align: justify; text-indent: 0.5in;"> <span lang="RO" style="font-size: 12pt; line-height: 24px;"></span></div> <div class="MsoNormal" style="background-color: white; color: #171510; font-family: Tahoma; font-size: 12px; line-height: 18px; text-align: justify; text-indent: 0.5in;"> <span lang="RO" style="font-size: 12pt; line-height: 24px;"></span></div> <div class="MsoNormal" style="background-color: white; color: #171510; font-family: Tahoma; font-size: 12px; line-height: 18px; text-align: justify; text-indent: 0.5in;"> <span style="height: 683px; left: 71px; top: -2px; width: 483px; z-index: 1;"></span></div> <table align="left" cellpadding="0" cellspacing="0" style="background-color: white; color: #171510; font-family: Tahoma; font-size: 12px; text-align: justify;"><tbody> <tr><td height="0" width="0"></td><td width="337"></td><td width="40"></td><td width="106"></td></tr> <tr><td height="403"></td><td align="left" colspan="3" valign="top"><span style="color: black; font-family: Arial, Helvetica, sans-serif; font-size: small;"><u><strike><img height="403" src="http://www.qreferat.com/files/constructii/231_poze/image018.gif" v:shapes="_x0000_s1027 _x0000_s1028 _x0000_s1029 _x0000_s1030 _x0000_s1031" width="483" /></strike></u></span></td></tr> </tbody></table>

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Scurtcircuitul monofazat, bifazat si trifazat

CALCULUL CURENTILOR DE SCURTCIRCUIT         Prin scurtcircuit se intelege contactul accidental,  a doua sau mai multe conductoare, aflate la potentiale electrice diferite.      Curentii de scurtcircu…

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