CIRCUTOR AFQ Series - Manual (Page 20)

AFQ-4W
20 Instruction Manual
CNL
SC
SC
I
I
R
=
Equation 2: Calculating the short-circuit ratio R
SC
.
In a real installation, the short-circuit current (I
SC
) in the PCL can be assessed by
having the voltage at the said point for two different load currents. For example,
full load, I
A
and 10% load, I
B
. If V
OC
is the rated voltage in a vacuum, the I
SC
, can
be calculated using the formula shown in Figure 13 :
Figure 13: Graphic for calculating I
SC
.
Figure 14 The safety factor (SF
h
) can be obtained from the graphic in:
Figure 14: Approximate graphic for calculating the SF
h
.