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3-Phase Current Measuring
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<blockquote data-quote="Joseph Howarth" data-source="post: 337477" data-attributes="member: 20227"><p>Hi Jay, if I remember my power triangles correctly <img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" class="smilie smilie--sprite smilie--sprite1" alt=":)" title="Smile :)" loading="lazy" data-shortname=":)" /> </p><p></p><p>one of the 20's will be the neutral, three phase likes to be balanced and the two 40's will induce current into the neutral</p><p></p><p>a good way to show it visually is to draw the triangle, draw a line that represents the 40A eg. 4cm then measure 45* and draw the next line 40A (4cm), 45* again then 20A (2cm). The length left between the end of the 3rd line and the start of the 1st will be 2cm = 20A that's the neutral current.</p><p></p><p>The only way to lower the neutral current is to balance the loads which is usually quite hard to do unless it's all motors (eg the UPS system in this factory has 48A, 36A and 16A respectively on each phase! due to each area of the shopfloor and offices having different amounts of computers).</p><p></p><p>As to telling which one is the neutral, it won't have a mains 'cut-out' fuse the 3 'Lines' will. :Salute </p><p></p><p><img src="http://i.ebayimg.com/t/3-phase-100a-cut-out-henley-service-cut-out-/00/s/MTIwMFgxNjAw/z/M~cAAMXQfFJRNM3a/%24%28KGrHqZ,%21o%21FEIPhpfI8BRNM3,URO%21~~60_35.JPG" alt="" class="fr-fic fr-dii fr-draggable " style="" />3 fuse carriers and the far right is the neutral ( no fuse carrier)</p></blockquote><p></p>
[QUOTE="Joseph Howarth, post: 337477, member: 20227"] Hi Jay, if I remember my power triangles correctly :) one of the 20's will be the neutral, three phase likes to be balanced and the two 40's will induce current into the neutral a good way to show it visually is to draw the triangle, draw a line that represents the 40A eg. 4cm then measure 45* and draw the next line 40A (4cm), 45* again then 20A (2cm). The length left between the end of the 3rd line and the start of the 1st will be 2cm = 20A that's the neutral current. The only way to lower the neutral current is to balance the loads which is usually quite hard to do unless it's all motors (eg the UPS system in this factory has 48A, 36A and 16A respectively on each phase! due to each area of the shopfloor and offices having different amounts of computers). As to telling which one is the neutral, it won't have a mains 'cut-out' fuse the 3 'Lines' will. :Salute [IMG]http://i.ebayimg.com/t/3-phase-100a-cut-out-henley-service-cut-out-/00/s/MTIwMFgxNjAw/z/M~cAAMXQfFJRNM3a/%24%28KGrHqZ,%21o%21FEIPhpfI8BRNM3,URO%21~~60_35.JPG[/IMG]3 fuse carriers and the far right is the neutral ( no fuse carrier) [/QUOTE]
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