Siemens Simatic S7-300 CPU 31xC Series User Manual

Wiring
6.2 Bonding the protective conductor to the mounting rail
S7-300, CPU 31xC and CPU 31x: Installation
Operating Instructions, Edition 08/2004, A5E00105492-05
6-3
6.2 Bonding the protective conductor to the mounting rail
Requirements
The mounting rail is fixed onto the mounting surface.
Protective conductor Connecting
Connect the rail with the protective conductor
using the M6 protective conductor bolt.
Minimum cross-section of the protective conductor: 10 mm
2
The figure below shows how the protective conductor has to be bonded to the rail.
Note
Always make sure of a low-impedance contact between the protective conductor and the
rail. You can achieve this by using a low-impedance cable, keeping it as short as possible
and contacting it to a large surface.
For example, an S7-300 mounted on a hinged frame must be connected to ground using a
flexible grounding strap.

Siemens Simatic S7-300 CPU 31xC Series Specifications

General

Series	S7-300 CPU 31xC
Power Supply	24 V DC
Communication Interfaces	MPI, PROFIBUS DP
Programming Languages	LAD, STL, FBD, SCL
Operating Temperature	0°C to +60°C
Memory	48 KB - 512 KB
Dimensions	40 x 125 x 130 mm (varies by model)