MI 3101 EurotestAT: Appendix E
Reduced low voltage supply systems
115
E.4.2 Fault loop impedance and prospective short-circuit current
Fuse or no circuit breaker selected
Fault loop impedance
Measuring range according to EN61557 is 0.32
19999
.
Measuring range (
) Resolution
(
)
Accuracy
0.00
9.99
0.01
10.0
99.9
0.1
100
19999
1
(10 % of r 5 digits)
Prospective fault current (calculated value)
Measuring range (A)
Resolution (A)
Accuracy
0.00
9.99
0.01
10.0
99.9
0.1
100
999
1
1.00k
9.99k
10
10.0k
23.0k
100
Consider accuracy of fault
loop impedance
measurement
The accuracy is valid if mains voltage is stable during the measurement.
IPSC calculation: .......................................IPSC = UN
kSC / ZL-PE
U
N
= 55 V; (44 V
Uinp
61 V) for selected 55 V single-phase system
U
N
= 63 V; (56 V
Uinp
70 V) for selected 63 V three-phase system
Maximum loading.......................................1.9 A / 10 ms
Nominal input voltage ................................55 V / 63 V, 14 Hz
500 Hz
Test possibilities ........................................L1 - PE and L2 - PE
