Sonel WMGBMPI525 User Manual page 21

3.3.4 Prospective short-circuit current
The meter always measures impedance Z
following formula:
where: Z - measured impedance, U - voltage that depends on settings of I
S
following Table:
where: U - nominal voltage of the network, U
n
On the basis of U
measurement at phase voltage or phase-to-phase voltage and takes it into account in the calculations.
If the voltage of the network being tested is outside the tolerance range, the meter will not be able
to determine a proper nominal voltage for the short-circuit current calculation. In such a case, horizontal
dashes will be displayed instead a short-circuit current value. The following diagram shows voltage
ranges for which short-circuit current value is calculated.
99
U =110V
n
99 103
U =115V
n
99
U =127V
n
99
U =220V
n
99
U =230V
n
99
U =240V
n
The selection in
MENU
I
k
I
k
nominal voltage selected (point 2.1.1), the meter automatically recognizes the
n
Voltage range for which impedance
110
171 190
121
115
127 180 200
127
198 220
114 140
198
MPI-525 – USER MANUAL
. The short-circuit current is calculated according to the
S
U
I 
k
Z
S
(U ) U = U
n n
U = U for U
0
(U )
0
U = U for U
n
- the voltage during the measurement.
0
measurement is made
209
220
242
220
242
230
253
207
216 240
264
button, according to the
k
< U
0 n
≥ U
0 n
418
380
342
400
360
415 440
373
440
U [V]
440
U [V]
440
U [V]
440
U [V]
440
U [V]
U [V]
19