Pfc

[Guest 004]

Indeed this conversation is going beyond the realms of normal sparkies, perhaps we can continue in the pub 'lol'
anyway good work

 

[Guest 004]

Take the BS 88 as your up stream, Breaking cap 80 Ka

now if you have a high pfc(50Ka) let say at the terminals of a 15ka rated Mccb, the let through energy of the bs 88 may be say 20 ka, so the mcb needs to be of a higher rating.

The pfc need to be calculated at each point back up protection may be provided by an upstream device, though this would need to be calculated and not assumed.

So down stream devices need to be able to break the 20 ka

never heard them terms before
.....chris and your qualifications are??

 

[Chr!s]

Well if your measuring the L - L, Zs = The line to line loop

so 400/ Zs + 2R1

Now i used the Three phase calculation Where ZS is the Line neutral loop as that was what i assumed you tested.So ill try again lol.

245 x 1.73 = 423 v L - L, 245/24500 = .01

R1= .022


So 400/1.73 divided Zs .= .01 + R1= .022 = 7656.25amps

For the line to line calculation at mcc we would need to know the PSCC where ZS = the line to line loop not the line to neutral loop.

Ill remove my earlier post, heavy question for a sunday lol