Testboy TV 455VDE-tester Testboy TV 455 Manuale Utente
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Testboy TV 455
TESTBOY TV 450
Fault loop impedance
43
5.5 Fault loop impedance and prospective fault current
Fault loop is a loop comprised by mains source, line wiring and PE return path to the
mains source. The instrument measures the impedance of the loop and calculates the
short circuit current. The measurement is covered by requirements of the EN 61557-3
standard.
See chapter
4.1 Function selection for
instructions on key functionality.
Figure 5.23: Fault loop impedance
Test parameters for fault loop impedance measurement
Test
Selection of fault loop impedance sub-function [Zloop, Zs
rcd
]
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.
Circuits for measurement of fault loop impedance
Circuits for measurement of fault loop impedance
L1
L2
L3
N
L2
L3
N
PE
R
E
Ro
L
PE
N
L/L
1
N/L2
PE/L3
Figure 5.24: Connection of plug cable and 3-wire test lead