MI 3110 EurotestIM
Measurements
– a.c. LV IT installations
26
5.2 Line impedance and prospective short-circuit current /
Voltage drop
Line impedance is measured in loop comprising of mains voltage source and line wiring.
Line impedance is covered by the requirements of the EN 61557-3 standard.
The Voltage drop sub-function is intended to check that a voltage in the installation
stays above acceptable levels if the highest current is flowing in the circuit. The highest
current is defined as the nominal current of the circuit's fuse. The limit values are
described in the standard EN 60364-5-52.
Sub-functions:
❑
Z LINE - Line impedance measurement according to EN 61557-3,
❑
ΔU – Voltage drop measurement.
See chapter
key functionality.
Figure 5.5: Line impedance
Figure 5.6: Voltage drop
Test parameters for line impedance measurement
Test
Selection of line impedance [Zline] or voltage drop [ΔU]
sub-function
FUSE type
Selection of
fuse
type
[---, NV, gG, B, C, K, D]
FUSE I
Rated current
of selected fuse
FUSE T
Maximum
breaking time
of selected fuse
Lim
Minimum short circuit
current
for selected fuse.
See Appendix A for reference fuse data.
Additional test parameters for voltage drop measurement
ΔU
MAX
Maximum
voltage drop
[3.0 %
÷ 9.0 %]
.
