Siemens Simatic S7-400 Installation Manual

Assembling and Installing Systems
A-30
Automation System S7-400 Hardware and Installation
A5E00850741-01
A.10 How to Protect Digital Output Modules against
Inductive Surge
Inductive Surge Voltage
Overvoltage occurs when inductive devices are switched off. Examples are relay
coils and contactors
Integrated Surge Arrester
S7-400 digital output modules are equipped with an integrated surge arrester
Additional Overvoltage Protection
Inductive devices require additional surge arresters only in following cases:
• If SIMATIC output circuits can be switched off by additionally installed contacts
(e.g. relay contacts).
• If the inductive loads are not controlled by SIMATIC modules.
Note: Consult the supplier of the inductors for the ratings of surge suppression
devices.
Example
Figure A-8 shows an output circuit that requires additional surge arresters.
Contact in output circuit
Inductivitys requires a circuiting
(see Figures A-9 and A-10)
D
Figure A-8 Relay Contact for EMERGENCY OFF in the Output Circuit

Siemens Simatic S7-400 Specifications

General

Programming Language	STEP 7 (LAD, FBD, STL, SCL, GRAPH)
Communication Interfaces	MPI, PROFIBUS
Power Supply	24 V DC, 120/230 V AC (Power supply modules are separate and chosen based on system requirements)
Operating Temperature	0°C to 60°C
Mounting	Rack mounting
Processor	CPU 412-1, CPU 414-2, CPU 416-2, CPU 417-4 (Different CPUs offer varying performance and features)
Relative Humidity	5 to 95% (non-condensing)