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U
C
contact voltage between conducting parts when they are touched simultaneously by a person or an animal (IEC-
61557).
U
F
fault voltage appearing during a fault condition between accessible conducting parts (and/or external conducting
parts) and the reference frame ground (IEC-61557).
U
Fk
fault voltage, in the event of a short-circuit, according to Swiss standard SEV 3569.
U
Fk
= Ik x Z
A
= U
REF
x Z
A
/Z
S
.
U
H-E
voltage measured between terminals H and E.
U
L
conventional maximum contact voltage (IEC-61557).
U
L-N
voltage measured between the L and N terminals.
U
L-PE
voltage measured between the L and PE terminals.
U
N
nominal test voltage in insulation measurement, generated between the M
W
and COM terminals.
U
N-PE
voltage measured between the N and PE terminals.
U
PE
voltage between the PE conductor and the local earth measured when the user presses the
TEST
button.
U
REF
reference voltage for calculation of the short-circuit current.
U
S-E
voltage measured between the S and E terminals.
Z
A
earth impedance in earth measurement on live circuit.
Z
S
impedance in the loop between the phase and the protective conductor.
Z
i
impedance in the loop between the phase and the neutral or between two phases (line loop impedance).
Z
L-N
impedance in the L-N loop.
Z
L-PE
impedance in the L-PE loop.
