Rules and Guidelines
Want to participate in the discussions? Please read our Community Rules and Guidelines. Need some help? Visit Support and Answers.

  • State Helpful Answer
  • Replies 6 replies
  • Subscribers 33 subscribers
  • Views 1910 views
  • Users 0 members are here
Options
You may also be interested in

Amtech - Excessive Earth Loop Impedance on SWA cables

Steven Wills (Steve)

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

Parents
  • +1

    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

  • 0 in reply to John Peckham

    Thanks John,

    The armour and CPC are selected but am I correct in thinking that initially the Zs is calculated using the armour only? And if this level is too high it results in an error? Then Amtech recalculates using the addtional CPC in parallel with the armour to give a lower reading which is acceptable, but this only comes up as a note? So ultmately, there is an initial error that is listed but the note says that in fact the Zs for this cable is ok? So does this note cancel out the error?

Reply
  • 0 in reply to John Peckham

    Thanks John,

    The armour and CPC are selected but am I correct in thinking that initially the Zs is calculated using the armour only? And if this level is too high it results in an error? Then Amtech recalculates using the addtional CPC in parallel with the armour to give a lower reading which is acceptable, but this only comes up as a note? So ultmately, there is an initial error that is listed but the note says that in fact the Zs for this cable is ok? So does this note cancel out the error?

Children
  • 0 in reply to Steven Wills (Steve)

    Steve

    I put my own cable data in to Amtech and then do a calculate. If I get errors on cables I will change the cable CSA, CPC CSA and adjust MCCB or ACB settings to correct any errors. I don't let Amtech calculate cable CSAs. I don't think Amtech calculates armour only if you have selected amour plus CPC and you have entered a CPC CSA.

    JP

Join us to get the best from IET EngX.

Joining EngX lets you personalise your experience so you stay up to date on the topics that interest you, plus you’ll be able to make connections who are looking to collaborate, exchange ideas and more.

Join us Not now

Community Rules & Guidelines