Amtech - Excessive Earth Loop Impedance on SWA cables

Question

Hi All, 
 
 I'm new to Amtech and I've been asked to review a model. 
 
 I'm looking at circuits that are SWA cables using the armour and an internal conductor as the CPC. There are various earth loop impedance errors listed where the Zs at the load end is too high, but what I can tell, Amtech firstly calculates the Zs using the armour only, and if this is too high it sees it as an error, but it then recalculates using the internal CPC in parallel with the armour to reduce the Zs to an acceptable value. There is a note listed referencing the same cable stating this, so I'm I correct in thinking that even though Amtech says this is an error but it actually isn't because of the note explaining the second calculation. 
 
 Steve

John Peckham · Accepted Answer

Steve 
 
 Amtech has a drop down option for the cable CPC. The options are SWA armour only, Armour plus CPC, CPC only and then you have an option for integral or separate CPC. 
 
 If you select armour plus CPC your Zs values should reduce and may be low enough. 
 
 When you have selected your option do a "Calculate" and then you will be able to see any errors in the design. 
 
 Hope this helps? 
 
 JP

Amtech - Excessive Earth Loop Impedance on SWA cables

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