Methods To Acquire Pfc

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alextrician

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Hello everyone.

 

Regulation 612.11 (PFC) state that PSCC and PEFC could be acquired by direct measurement (at the origin of installation and other relevant points) ;  calculated (V/Ze) and...." by other methods".

 

That the "other methods" are? 

 

The Generic Schedule of test Results requires a Ipf value at DB, so it can't be guessed or assumed,or can it?

 

The only thing that comes to my mind is that on a 230V installation (for example) the value of PFSC can't be higher than 6kA

 

Just curious about it....and I apologise for the mess I have done with my previous post.

Sorry Admin

Thank You.

 

 

 

 
That the "other methods" are? 
enquiry. DNO should have this info

 

The only thing that comes to my mind is that on a 230V installation (for example) the value of PFSC can't be higher than 6kA 

 

 
why not?

unusual to see it higher than 6kA in a house (or anything above 2-3), but there is nothing to say it cant be higher than 6kA

 
Could be 16kA for a single phase supply or 25kA for a three phase one.....

Use these figures for design purposes, no matter WHAT you measure...... Why???? Cos what if you design using lower measured figures, and then, the DNO go and reinforce the network [build a new substation next door] then what will happen........

john....

 
Thanx everyone for your answers.

yes, sorry, for domestic installations is less probable for the PFC value to exceed  6kA. apart from big cities where fault current (Ipf) might be higher.

Also earthing system and location of the installation, determines the value of PFC.

 
alextrician,

WPD for example, in the link above, give 16kA as the pfc for domestic single phase installs remember, so this would be the PEFC & PSCC @ the origin for TN-C-S & TN-S, it would also be the PSCC for TT, but, obviously not the PEFC.

Please think a little about this and give us some of your ideas and we will help you to get fully to grips with this if you wish.

 
I will have a go at it....I started this topic to learn some things, after all

The PEFC is determined by the low resistance of earth and the parallel path to earth of the consumer side ( I am thinking of bonding connection as the test is taken with the installation energised and earthing and bonding in place). The PSCC is determined by the low resistance of the supplying cables. this mean that value is assumed for the closest consumer to the transformer point for safety reasons. To follow the WPD example, 16kA is a maximum value in a worse case scenario. the true value of PFC only can be determined by direct measurement.at the origin of installation. The formula Ipf=V/Ze is just give an idea of the value..... 

 
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