Electrical Installation Safety Trainer
AD 1 - MI 3399
57
where:
U
N
– nominal value, determined according to the measured voltage (U
L-N
).
In a 3-phase TN/TT system the maximum allowed impedance result for a 6A B type
fuse with 200ms trip-out time is
7,3
Ω
5
. If a 1-phase TN/TT system is used then 6A gG
type fuse with 200ms trip-out time is used. In this case the allowed impedance is
4,6
Ω
.
As is seen from the screens above the impedance, voltage drop and I
PSC
are within
limits and the test is marked as passed.
Expected results with a simulated error
During the test we add an error in the circuit introducing an additional 10
Ω to the wiring
simulating a wiring error in a TN/TT earthing system. The Application Trainer does not
support error simulation on an IT earthing system. To simulate an error on a 3-phase
TN/TT system (as per our example) enable the switch
S14
in the Application Trainer:
5
See chapter 1.4 Ensurance of Safety for more details on fuse trip-out times and impedances.
Summary of Contents for MI 3399
Page 27: ...Electrical Installation Safety Trainer AD 1 MI 3399 27...
Page 46: ...Electrical Installation Safety Trainer AD 1 MI 3399 46 3 Exit settings...
Page 74: ...Electrical Installation Safety Trainer AD 1 MI 3399 74...
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