Installation
70
1SVC 440 795 M1100
Calculating the cable length for a known cable
resistance
If the resistance of the cable per unit length is known
(resistance per unit length R’ in O/m), the entire cable
resistance R
L
must not exceed the following values. R
L
depends on the selected baud rate:
l
max
= Maximum cable length in m
R
L
= Total cable resistance in O
R’ = Cable resistance per unit length in O/m
Calculating cross-section with known cable lengths
The minimum cross-section is determined for the known
maximum extent of the network.
l = Cable length in m
S
min
= Minimum cable cross-section in mm
2
r
cu
= Resistivity of copper, if not otherwise stated 0.018 Omm
2
/m
Baud rate
Cable resistance R
L
Kbaud O
10 to 125 F 30
250 F 25
500
1000
F 12
l
max
=
R
L
R’
S
min
=
l × r
cu
12.4
h
If the calculation result does not correspond to a standard
cross section, take the next higher cross section.
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