Connecting the NET network
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MN05013005E
73
Calculating the cable length with known cable resistance
If the resistance of the cable per unit of length is known
(resistance per unit length
R
' in
Ω
/m), the entire cable
resistance
R
L
must not exceed the following values.
R
L
depends on the selected baud rates:
l
max
= maximum cable length in m
R
L
= Total cable resistance in
Ω
R
' = Cable resistance per unit length in
Ω
/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
ρ
cu
= resistivity of copper, if not otherwise stated 0.018
Ω
mm
2
/m
Baud rate
Cable resistance
R
L
KBaud
Ω
10 to 125
30
250
25
500
1000
12
l
max
=
R
L
R
'
S
min
=
l
×
ρ
cu
12.4
J
If the result of the calculation does not yield a standard
cross-section, the next larger cross-section is used.