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Do not use more than 20 indoor stations per strand. For systems with
more video indoor stations plan to use video distributors (FVY1200,
FVY1400).
Up to 64 front-door stations (16 of them video front-door stations) and
almost an unlimited number of indoor stations can be connected within
one system polarity-free (a/b; polarity-free only in 6-wire operation).
Thus, a suitable power supply and control unit is to be used.
Table 1: loop resistances
length of the
line a-b/ M-P
in m
cable diameter
0.6 mm
0.8 mm
loop resistance in
Ω
10
1.28
0.71
20
2.55
1.43
30
3.83
2.14
40
5.10
2.86
50
6.38
3.57
60
7.65
4.29
70
5.00
80
5.71
90
6.43
100
7.14
Principle loop resistance
Measurement loop resistance
None of the devices (AS, IS or FE) should
ever be located more than
8 Ohm
away
from the power supply and control unit (VS).
Switch off the 230 V / 50 Hz of
the VS.
Install the a-b short-circuit at
VS.
Other devices do not disturb the
measurement and can stay
connected.
