MI 3110 EurotestIM
Measurements
– a.c. LV IT installations
30
5.3 First fault leakage current (ISFL)
First fault leakage current measurement is performed in order to verify the maximum
current that could leak into PE from observed line. This current flows through the
insulation resistance and reactance (capacitance) between the other lines and PE when
the first fault is applied as short circuit between observed line and PE.
See chapter
key functionality.
Figure 5.11: ISFL measurement
Test parameters for first fault leakage current measurement
Limit
Maximum leakage current
[OFF, 3.0 mA ÷ 20.0 mA]
Test circuit for first fault leakage current
Figure 5.12: Measurement of highest first fault leakage current with 3-wire test lead
Figure 5.13: Measurement of first fault leakage current for RCD protected circuit with 3-
wire test lead
