Calculating SWA cpc using the armour and separate conductor

[Ronniechew]

Hi

I can you tell me if the software uses the calculations layed out in GN6 amd GN8 that adopts PD CLC/TR 50480:2011 which adopts annexe NA (for the Uk) methods of working out the  size of cpc for a 90 degree SWA thermosetting cable in excess of 100A per phase. Separate cpc and armouring alone. 

Within it contains calculations that the UK now uses (since 2015) to determine the magnetic effect the armour has upon a a separate parallel cpc run with the armour for a thermosetting  SWA cable taking into account the DC resistance of armour

It was adopted into BS7671 2008 (2015) Amd 3. You might remember it being the document that changed the Maximum earth fault loop impedances given in Tables 41.2, 41.3, 41.4 and 41.6. Back then.
GN6 references it (Page  81-83) along with GN8 (page 140) And app 4 BS7671 2018 SECTION 2.5

Thank you

[admin]

Hello,

The GN6 notes have been considered for the SWA resistance calculation.

The PD CLC/TR 50480:2011 NA correction has not been considered though. This is something we will look at and most probably include as an option.

Thank you for the feedback!

[admin]

Further to the above, we will include the option to consider the magnetic effect of the SWA when a separate CPC is involved based on the PD CLC/TR 50480:2011 UK NA.

Also, we will include the other checks about the separate cpc withstand and also the SWA cpc withstand, based on the portion of the Ief in each case as mentioned in the UK NA.

I hope that helps and many thanks again for the feedback.