Cables And Lines; Calculation Tool For Cable Cross-Sections - Siemens SiPass AC5160 Installation Instructions Manual

8

Cables and Lines

8.1

Calculation Tool for Cable Cross-Sections

Siemens Building Technologies
Fire & Security Products
If remote SiPass components are to be connected to the ACC, the following calculation tool might be
helpful.
Use a shielded weak-current cable type IY (St)Y for all bus lines. The cross-
sections of the leads have to be chosen by considering the following criteria:
power consumption of the connected system components/modules
Line length
Intermittently needed switching current (e.g. relay exits)
However, a min. diameter of 0.6 mm per lead is required.
The supply voltage in all system components/modules may not fall below 18 V DC.
With a min. permissible battery voltage of 21 V, this yields a max. voltage drop of
3V DC pertaining to the entire line length.
(Caution: Total length = line to and back).
Resistance values for the conductor cross-section calculation:
Line length = 100 m
Wire Ø 0.6 mm (0.28 mm
Wire Ø 0.8 mm (0.56 mm
Calculation formulae
Voltage drop with applied current
⋅
L I
=
U
χ
⋅
A
Conductor cross-section with applied current
and 0.5 V voltage drop along line:
⋅ ⋅
L I L I
= =
A
χ
⋅ ⋅
U 56 0 5 .
2
) ⇒ 6.5 Ohm
2
) ⇒ 3.6 Ohm
L
= Line length of line leading to unit and
back
in meters
I = Current in ampere
χ = spec. conduct. value for copper
=
56
A = Lead cross-section in mm
U = Voltage in V
=
....... mm 2
Cables and Lines
m
Ω ⋅
mm 2
2
A24205-A335-B219.doc
17
08.2004