NOVA AND NOVA PRO
Measurements
37
Figure 5-30: Example of loop impedance measurement results
Notes:
Displayed results:
Z ...............
Fault loop impedance,
I
SC.....................
Prospective fault current (displayed in amps),
❑
The specified accuracy of test parameters is valid only if mains voltage is stable during
the measurement.
❑
The Fault loop impedance measurement trips RCD protected circuits.
5.4.2.
The fault loop impedance test RCD (for RCD protected circuits)
The fault loop impedance is measured with a low test current to avoid tripping the RCD. This
function can also be used for fault loop impedance measurement in system equipped with
RCDs which have a rated trip-out current of 30 mA and above.
Prospective fault current (IPFC) is calculated on basis of measured resistance as
follows:
Where:
𝐼
𝑃𝐹𝐶
=
𝑈
𝑁
×
𝑠𝑐𝑎𝑙𝑖𝑛𝑔
𝑓𝑎𝑐𝑡𝑜𝑟
𝑍
𝐿−𝑃𝐸
Nominal input voltage U
N
Voltage range
115V
(93 V
U
L-PE
134 V)
230V
(185 V
U
L-PE
266 V)
