Adnan Hasan
Member
- Location
- baghdad, Iraq
How do I arrange 120 cables (1*300 mm2), 400 Vac in parallel ventilated trough cable trays to mitigate the effects of magnetic and electric fields? Please notice that my grounding system is TN-S type.
1) they are 30 sets of 3-ph, 4 x 1/c. (EGC shall be considered as well)Adnan...
1) Are you contemplating the installation of 40 sets of 3-ph, 3 x 1/c wire systems, or 30 sets of 3-ph, 4 x 1/c wire systems?
2) Are you concerned only about how physical arrangement impacts EMI, without economic consideration?
Regards, Phil Corso
N is also 300 mm2. PE shall be calculatedAndnan...
Clarifying my "economic" comment... are N and PE conductors also 300 mmq in size?
Phil
I think you meant B-A for the last pairing...The simplest way is to bond all the cables in groups of 2*4- as follows: first group, upper layer C-N, down A-B; second group upper N-C down B-C. In addition, is to keep a two*cable diameter clearance between two adjacent groups.
are you leaving spaces between groups?I think you meant B-A for the last pairing...
Is this based on empirical data, authoritative reference, or speculation?
I would think it better...
CN AB CN AB CN AB (top)
AB CN AB CN AB CN (bottom)
Single conductors are required to be distributed evenly across the width of the cable tray [392.22(B) general statement]. Does not apply to a "cabled" group.are you leaving spaces between groups?
example:
CN AB CN
AB space CN space AB
If I dont want to leave space, shall I multiply by grouping factor (derating)?
300mm? = 592,058cmilFirst 300 mm^2=600 MCM:weeping: .
Please cite reference. This is not an NEC requirement.Second the grouping has to be as follows:
CN NC CN NC
AB BA AB BA
in order to mitigate current unbalance.
Not an NEC compliant method.If your cable is XLPE insulated and the maximum air temperature is 40dgr.C and you cannot keep 2.15 times the cable diameter clearance you have to calculate according to:
ICEA/NEMA STANDARDS PUBLICATION NO.P-54-44/WC5
"Ampacities of Cables in Open-top Cable Trays"
Conductor diameter is not what is being measured, especially when stranded, or the conductor has any other gaps within the periphery of its cross section. 600kcmil refers to the kcmil sum of all strands' cross-sectional area. I believe it is the same for metric-sized conductors. I got the cmil equivalent of 300mm? from a General Cable equivalents chart.1)The conductor diameter is the same for both 300 sqr.mm and 600 MCM [depends on how it is built-concentric stranded, compressed or compacted].
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