User manual

34
VDE 0100-compliant demonstration case
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Starting conditions:
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  -803EULGJHLVFRQQHFWHG
Switch position at the BENNING IT 110 / IT 120:
  =
s
/I
N/3(
, hypofunction: Z
s rcd
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Note:
In the TT system, all bodies of the electrical equipment are connected to a joint earth connection R
E
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L-PE
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is relatively low. Hence, a fuse or a line safety switch would trip only after a relatively long time and
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L-PE
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E
In practice, R
E
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included.
Limiting values: see DIN VDE 100-600
The voltage must be cut off at the latest when a contact voltage U
B
   9 occurs between the
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E
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E
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ǻ1
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E
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Preferably, the contact voltage U
B
should be much lower than 50 V. This means that a lower earthing
resistance R
E
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E
ȍ
Loop impedance in the TT earthing system
Measuring point Measured value
mains socket
Z
s
= Z
[
ȍ
e.g. Z
s
ȍ,
k
= 64,7A
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Z
s
= Z
[
ȍ
e.g. Z
s
 ȍ,
k
 $
Error:UHPRYHEULGJH7177$8;
5
E/LOOP
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mains socket
Z
s
= Z
[
ȍ
e.g. Z
s
 ȍ,
k
= 0,15 A
Z
[
= loop impedance at the input of the supplying mains socket
Measuring current: for Z
s
$PVIRU=
s rcd
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