Testboy TV 455 - Line Impedance and Prospective Short Circuit Current

®
TV 450/455 Line impedance
46
5.6.1 Line impedance and prospective short circuit current
Circuits for measurement of line impedance
L1
L2
L3
N
PE
R E Ro
LPEN
L
/
L
1
N
/ L 2
P E / L 3
N/L2
L
/
L
1
PE/L3
Figure 5.28: Phase-neutral or phase-phase line impedance measurement – connection
of plug commander and 3-wire test lead
Line impedance measurement procedure
 Select the Z-LINE sub-function.
 Select test parameters (optional).
 Connect test cable to the instrument.
 Connect test leads to the item to be tested (see figure 5.28).
 Press the TEST key to perform the measurement.
 Store the result by pressing the MEM key.
Line to neutral Line to line
Figure 5.29: Examples of line impedance measurement result
Displayed results:
Z..............Line impedance,
ISC............Prospective short-circuit current,
Lim ..........Low limit prospective short-circuit current value or high limit line
impedance value for the UK version
.
Prospective short circuit current is calculated as follows:
Z
kUn
I
SC
SC
×
=
where: