NOTE
With the LMS500, the external diameter of the joint cable must not exceed 9 mm due
to the cable entry.
6.5.3
LMS5x1 Outdoor cable cross-section
The Outdoor devices can be connected using the following optional accessories,
:
•
Standard cables up to 20 m with M12 male connectors
•
For particularly long male cable connectors of over 20 m with/without M12 con‐
nectors, there is a compact connection unit for each device type.
Example of maximum cable connection
Prerequisites:
•
Steady state of the voltage supply
•
Only applies for copper cable material
•
For the line length calculation, the permissible voltage loss in the particular appli‐
cation must be specified.
Table 38: Length of cable and voltage drop
Cable properties
A = 0.75 • 10
-6
m²
Cross-section of the cable surface [m
2
]
ρ = 1.72 • 10
-8
Ωm
Specific resistance of copper [Ωm]
α = 3.9 • 10
-3
K
-1
Temperature coefficient of copper [1/°C]
Ambient conditions
T
0
= 20 °C
Reference temperature [°C]
T = 80 °C
Cable temperature [°C]
Cable load
I = 2.5 A
Load current [A]
Voltage drop on the cable
ΔV = 4.245 V
Voltage drop on the cable [V]
Formula for permissible length of cable
L =
2•I•ρ•(1 + α•(T - T
0
))
Δ V•A
= 30 m
Permissible length of cable [m]
To check whether the voltage drop can be maintained with a calculated length of cable,
the following calculation is possible:
Table 39: Voltage drop
Formula for permissible voltage drop
L = 30 m
Cable length [m]
I•2•L
•ρ•(1 + α•(T - T
0
))
Δ V =
= 4.245 V
A
Permissible voltage drop ΔV [V]
Length of cable L [m]
Cross-section of cable surface A [m
2
]
Specific resistance of copper [Ωm]
Temperature coefficient of copper [1/°C]
Cable temperature [°C]
The minimum voltage with which the device may be operated is the recommended 20 V
6
ELECTRICAL INSTALLATION
66
O P E R A T I N G I N S T R U C T I O N S | LMS5xx
8013796/1ALS/2021-03 | SICK
Subject to change without notice
