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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="Sparkywannabe" data-source="post: 495892" data-attributes="member: 32689"><p>I've done most of the stuff but something doesn't add up to me at the adiabatic equation. </p><p></p><p>Question 5</p><p></p><p>Regulation 543.1.3 of BS7671 for Fridge circuit 2</p><p></p><p>Wired in 70°C single core t/p in pvc conduit</p><p></p><p>Ambient temperature 35°C </p><p></p><p>protective device BSEN60898 16A Type C</p><p></p><p>Length of run is 9.15m</p><p></p><p>Quoted fault at pool/cafe 3.7ka</p><p></p><p>R1+R2 = 14.82x1.06x1.2x9.15÷1000= 0.17Ω</p><p></p><p>Zdb value = 0.11Ω</p><p></p><p> Zdb+ (r1+r2) = 0.11+0.17= 0.28Ω</p><p></p><p>Zs= 0.28</p><p></p><p>Ipf = Vo÷0.28 —&gt; 230÷0.28=822A</p><p></p><p>Adiabatic equation</p><p></p><p>S=√I2T÷K</p><p></p><p>S=√8222x0.1÷115= 2.26mm2</p><p></p><p>The cross-sectional area for the fridge circuit 2 is 2.26mm2 which complies with the regulation 543.1.3 of BS7671.</p></blockquote><p></p>
[QUOTE="Sparkywannabe, post: 495892, member: 32689"] I've done most of the stuff but something doesn't add up to me at the adiabatic equation. Question 5 Regulation 543.1.3 of BS7671 for Fridge circuit 2 Wired in 70°C single core t/p in pvc conduit Ambient temperature 35°C protective device BSEN60898 16A Type C Length of run is 9.15m Quoted fault at pool/cafe 3.7ka R1+R2 = 14.82x1.06x1.2x9.15÷1000= 0.17Ω Zdb value = 0.11Ω Zdb+ (r1+r2) = 0.11+0.17= 0.28Ω Zs= 0.28 Ipf = Vo÷0.28 —> 230÷0.28=822A Adiabatic equation S=√I2T÷K S=√8222x0.1÷115= 2.26mm2 The cross-sectional area for the fridge circuit 2 is 2.26mm2 which complies with the regulation 543.1.3 of BS7671. [/QUOTE]
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Help with Electrical design unit Level 3
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