"f " factor in short-circuit cals.

[ks1]

Hey,

Can someone explain to me what the "f " factor represents in short-circuit
calculations? Is it the total "load" (for lack of a better word) that the fault sees?

Thanks

 

[zog]

It represents the impedence of the bus or cable between the 2 points the fault current is calulated. It is used to determine your Multiplier ("M")

 

[RETRAINDAILY]

It represents the impedence of the bus or cable between the 2 points the fault current is calulated. It is used to determine your Multiplier ("M")

Do you get that k value from your effective z ?in table 9?

 

[zog]

Do you get that k value from your effective z ?in table 9?

No idea what table 9 is, from where???

3? Faults f = (1.732 x L x I)/(C x EL-L)

1? Line-to-Line f =(2 x L x I)/( C x EL-L)

1? Line-to-Neutral f =(2 x L x I)/( C x EL-N)

Where:
L = Length (feet) of circuit to the fault.
C = Constant from C value tables. For parallel runs, multiply C values by the number of conductors per phase.
I = Available short-circuit current in amperes at beginning of circuit.

 

[RETRAINDAILY]

so were does one find C value table ?

 

[RETRAINDAILY]

all I can find is

http://www.guajara.com/wiki/en/wikipedia/c/co/constant.html

 

[jumper]

all I can find is

http://www.guajara.com/wiki/en/wikipedia/c/co/constant.html

Here is a link that might help. It explains the calcs that Zog posted in a little more detail.

http://www.cooperbussmann.com/pdf/8744b1f2-9436-426d-a924-5c4e9d57d93c.pdf

 

[zog]

so were does one find C value table ?

last page of jumpers link