pfc

[i=p/u]

how do you get pfc measurement, is it u/ze? it says 0.9KA and im geting 0.4KA, its 230v and Ze is 0.58??? hmmmm help

 

[Sparky Ninja]

A designer would not have the benefit of a measured PFC to work with when designing a new installation,he may only have the declared Ze from the supplier.

Calculation is then your only option.

Touche, we can't work miracles.

 

[Geoffsd]

Whats 'Not at the D.B.'?

It was stated that PEFC was measured with bonding connected.

 

[Sparky Ninja]

It was stated that PEFC was measured with bonding connected.

Oh ok. Well it is.

 

[WayneL]

To be clear, the actual calculation for PFC is Uo or U divided by the Loop Impedance

Which 'Loop Impedance' you use depends on the value that you require.

For PEFC you would use the 'Line'/'Earth' Loop Impedance with 'Earthing Conductor' connected to the MET - so, basically, Zs at the 'Main Switch'. (You can't call it Ze, because the 'Earthing Conductor' is connected!)

For PSCC you would use the supply 'Line'/'Neutral' Loop Impedance.

For PSCC (3 phase), you would use U (400v) divided by the supply 'Line'/'Line' Loop Impedance.

The highest of these values would, of course. be your PFC.

Simple

 

[Geoffsd]

Ok I see the distinction now. I was assuming that 'at the supply' was the same as at the DB incomers (If near the cut-out).

Therefore Ze would be all there was.

Just for clarity though, - there cannot be a calculation for or measurement of PFC,as such, as it is the greater of two other calculations or measurements.

 

[WayneL]

Just for clarity though, - there cannot be a calculation for or measurement of PFC,as such, as it is the greater of two other calculations or measurements.

Now that I will have to agree with.

 

[Deleted member 26818]

The term for Ze with bonding conductors and CPCs all conected is or used to be Zdb.
With TN-C-S, both the PEFC and the PSCC would be the same, if there were no parallel earth paths.

 

[Guest123]

I would just like to add that in no way was I advocating calculation of PFC over an actual measurement, merely stating that in some instances it is the only option.....in-accurate as it may be.

 

[i=p/u]

its from the exercises from chris kitchers testing and insoection book, but thanks for all your replies and loads of them at that..

its about filling in the the test forms on information he gave and pfc is 0.9KA , so would this be a measurment or can this be calculated from what he gave me.. its me working out how he got these, well trying too and good morning

 

[i=p/u]

another quick 1.... i have a tns supply protected protected by bs1361 main fuse and bs5377 asmain circuit breaker,

would this still be ADS or ebadd???

 

[malcolmsanford]

ADS as EEBAD is no longer recognised in the regs.

What as BS 5377 got to do with electrical work?

 

[topquark]

ADS as EEBAD is no longer recognised in the regs.

What as BS 5377 got to do with electrical work?

Maybe it applies when wiring in a washing machine

 

[Guest123]

ADS as EEBAD is no longer recognised in the regs.

What as BS 5377 got to do with electrical work?

I'm not entirely sure where the laundering effects of a cotton control cloth come in either.....

 

[Deleted member 26818]

Cloth covered fuse holders?

 

[topquark]

Cloth covered fuse holders?

Wash them before use so that the current flows freely coz it lowers the resistance?