User Manual

GMC-I Messtechnik GmbH 29
8.3 Settings for Short-circuit current Calculation – Parameter I
K
Short-circuit current I
K
is used to test shutdown by means of an
overcurrent protective device. In order for an overcurrent protec-
tive device to be tripped on time, short-circuit current I
K
must be
greater than tripping current Ia (see table 6 in section 21.1). The
variants which can be selected with the “Limits” key have the fol-
lowing meanings:
I
K
: Ia The measured value displayed for I
K
is used without
any correction to calculate Z
L-PE
.
I
K
: Ia+Δ% The measured value displayed for Z
L-PE
is corrected
by an amount equal to the test instrument’s measuring
uncertainty in order to calculate I
K
.
I
K
: 2/3 Z In order to calculate I
K
, the measured value displayed
for Z
L-PE
is corrected by an amount corresponding to
all possible deviations (these are defined in detail by
VDE 0100, part 600, as Z
s(m)
≤ 2/3 x U
0
/Ia).
I
K
: 3/4 Z Z
s(m)
≤ 3/4 x U
0
/Ia
Z Loop impedance
I
K Short-circuit current
U Voltage at the test probes, “U
N
” is displayed if voltage Umax.
deviates from nominal voltage by 10%
f Frequency of the applied voltage,
“f
N” is displayed if frequency fmax. deviates from nominal fre-
quency by 1%
Ia Tripping current (see data sheet for circuit breakers / fuses)
Δ % Test instrument inherent error
9 Measuring Line Impedance (Z
L-N
function)
Measuring Method (internal line resistance measurement)
Supply impedance Z
L-N
is measured by means of the same
method used for loop impedance Z
L-PE
(see section 8 on page
27). However, the current loop is completed via neutral conductor
N rather than protective conductor PE as is the case with loop
impedance measurement.
Select Measuring Function
Connection:
Schuko
Connection:
2-Pole Adapter
Set Parameters
Press the softkey shown at the left in order to switch
back and forth between the country-specific plug
insert, e.g. SCHUKO, and 2-pole adapter. The
selected connection type is displayed inversely
(white on black).
Limit value:
I
K
< limit value
U
L
⏐ R
L
Z
L-N
Nominal current:
Diameter: 1.5 to 70 sq. mm
Cable types: NY..., H07...
Number of wires: 2 ... 10-strand
2 ... 160 A, 9999 A
Tripping characteristics:
A, B/L, C/G, D, E, H, K, GL/GG & Factor