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Do-It-Yourself (DIY) Question & Answer Forum
Help with Electrical design unit Level 3
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<blockquote data-quote="king84" data-source="post: 497505" data-attributes="member: 32812"><p>Hi I am also trainee like you but There are something that I dont understand in your calculations .</p><p></p><p>you stated R1+R2 = 14.82x1.06x1.2x9.15÷1000= 0.17Ω could you explain where did you get 1.06 from??? as this circuit is 70 degree so I am assuming its incorportated so I3 would be 1.20 or if not incorportated than it would be 1.04??</p><p> </p><p> Furthermore I found max R1+R2 = Zs max-Ze/ I3*Length multiply 1000 which gave us 115.17 so I went to I1 table Onsite guide and choose 2.5/1 which is 25.51</p><p> </p><p> using this in Zs=Ze+(R1+R2*Length*1.2/1000) gives us 0.11+0.28 =0.39</p><p></p><p>IpF= 230/0.39 = 589.7</p><p></p><p>Adiabetic equation </p><p> S=√I2T÷K</p><p></p><p>S=√589.7^2*0.1/115</p><p></p><p>=1.62 mm</p><p></p><p>so the next available you can choose is 2.5 CPC</p></blockquote><p></p>
[QUOTE="king84, post: 497505, member: 32812"] Hi I am also trainee like you but There are something that I dont understand in your calculations . you stated R1+R2 = 14.82x1.06x1.2x9.15÷1000= 0.17Ω could you explain where did you get 1.06 from??? as this circuit is 70 degree so I am assuming its incorportated so I3 would be 1.20 or if not incorportated than it would be 1.04?? Furthermore I found max R1+R2 = Zs max-Ze/ I3*Length multiply 1000 which gave us 115.17 so I went to I1 table Onsite guide and choose 2.5/1 which is 25.51 using this in Zs=Ze+(R1+R2*Length*1.2/1000) gives us 0.11+0.28 =0.39 IpF= 230/0.39 = 589.7 Adiabetic equation S=√I2T÷K S=√589.7^2*0.1/115 =1.62 mm so the next available you can choose is 2.5 CPC [/QUOTE]
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Help with Electrical design unit Level 3
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