MI 3101 EurotestAT: Measurements
Fault loop impedance
59
Fault loop impedance measurement procedure
Select the
Z-LOOP
function.
Select test
parameters
(optional).
Connect
test cable to the EurotestAT
.
Connect
test leads to the tested object (see
figure 5.19
).
Press the
TEST
key.
After the measurement is finished
store
the result (optional).
Figure 5.20: Examples of loop impedance measurement result
Displayed results:
Z ..............Fault loop impedance,
I
SC
............Prospective fault current,
R..............Resistive part of loop impedance,
Xl .............Reactive part of loop impedance.
Prospective fault current I
SC
is calculated from measured impedance as follows:
Z
k
Un
I
SC
SC
where:
Un ........Nominal U
L-PE
voltage (see table below),
ksc .......Correction factor for Isc (see chapter
4.4.2
).
U
n
Input voltage (L-PE)
110 V (93 V
U
L-PE
134 V)
230 V (185 V
U
L-PE
266 V)
Notes:
High fluctuations of mains voltage influence the measurement results. The noise
sign
is displayed in the message field in such case. Repeat the measurement.
Isc is not calculated in case the terminal voltage monitor does not detect voltage
state that corresponds to the selected supply system, indication
.
This measurement will trip-out RCD in RCD-protected electrical installation if FUSE
is selected as breaking device instead of RCD.
