Grounding The Panel Pc; Fig. 7 Cp77Xx_Protective Conductor Connection - Beckhoff CP77 Series Manual

4.3.1

Grounding the panel PC

Potential differences are minimized and electrical currents are diverted to the ground through grounding or
potential equalization of electronic devices. This is to prevent dangerous touch voltages and electromagnetic
interference.
On the rear side of the panel PC there is the protective conductor connection PE (see Fig. 7), which ensures
both the protective earthing of the PC and the functional earthing. Use wires with a cross-section of at least
2
4 mm or a flat conductor for the ground connection, as the circumference of the conductor should be as
large as possible.
Fig. 7: CP77xx_protective conductor connection
Protective earth
The protective grounding of a device serves to avoid dangerous touch voltages. According to the EN
60204-1 standard (Chapter 8 Potential equalization), protective grounding is required if:
• the device exceeds dimensions of 50 mm x 50 mm,
• the device can be touched or encompassed over a large area,
• contact between the device and active parts is possible,
• an insulation fault may occur.
By connecting the protective earth conductor (PE), you establish a low-resistance protective earth of the
panel PC and thus avoid dangerous touch voltages.
EMC
Hardware damage due to electromagnetic interference
The use of the panel PC without a functional earth can lead to material damage due to electromagnetic
interference.
• Only use the device with functional earth.
Electromagnetic compatibility (EMC) of the panel PC includes on the one hand not affecting other devices
and equipment by electromagnetic interference and on the other hand not being disturbed by electrical or
electromagnetic effects itself.
To do this, the panel PC must comply with certain protection requirements. The panel PC has EMC
interference immunity according to EN 61000-6-2. The EMC interference emission of the device meets the
requirements of EN 61000-6-4.
The functional earth is necessary for the EMC of the device. The functional earth is also established via the
connection of the PE protective conductor.
CP77xx
NOTICE
Version: 3.4
Commissioning
21