1st edition, 12.02.2021
7000.05071, 1st edition, 12.02.2021
7000.05071
Installation
67
4.3.2
Functional earthing
DANGER!
Danger to life through ground leakage currents
≥
3.5 mA
Check the earthing of the devices for proper installation.
The earthing system is essential for discharging parasitic current and for a potential distri-
bution in the system that is as uniform as possible. The most efficient systems have a star or
mesh shape. A star-shaped connection is easier to implement.
Ensure an adequate cross section and a very good electrical earth connection so that
the contact resistances are low not only for the low-frequency currents.
The earth connection can be improved, e.g., by removing the oxide layers from the ends
of conductors with fine sandpaper.
For electrical safety:
Earth in accordance with current standards and guidelines.
Use separate protective earth conductors for all necessary parts (e.g., mains supply,
motor, controller).
Keep earthing cable as short as possible.
For functional earthing:
Use a braided shield that is meshed as tightly as possible.
Direct contact with the earth plate is to be preferred.
Therefore, avoid contact with the controller and then with the earth plate.
Connections made over a large surface area are to be preferred.
4.3.3
Cable routing
The cable routing depends on various factors, such as:
Is the cable shielded, twisted?
Were interference-reducing measures taken?
What material and what cable routing are used in the cable duct?
Over what surface is the cable routed?
Observe the following when laying the cables:
Use a full-surface, u-shaped and, if possible, metal cable duct.
Lay the cables near the corners of the cable duct.
Separate the cables by function where possible.
Maintain distances when laying the cables.
The distances may vary depending on the zone in the switching cabinet.
If possible, all cables should be twisted pairs or twisted and shielded in function groups
(e.g., motor phases together, Hall sensors and supply together).