General Rules And Regulations For S7-300 Operation - Siemens CPU 313C Hardware And Installation Manual

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A number of components and protective measures are prescribed for plant
installations. The type of components and the degree of compulsion pertaining to
the protective measures will depend on the VDE specification applicable to your
particular plant.
The table below shows components and protective measures.
Table 5-7
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Disconnecting devices for
control systems, sensors
and actuators
Short-circuit/overload
protection:
In groups for sensors and
actuators
Load power supply for AC
load circuits with more than
five electromagnetic devices
1) This column refers to the numbers in the diagram in the Summary diagram: Grounding
section.
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Additional information on protective measures is in the Appendix.
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General Rules and Regulations for S7-300 Operation

S7-300 Automation System, Hardware and Installation: CPU 31xC and CPU 31x
A5E00105492-03
VDE specifications for the installation of a PLC system

(1) ... Part 460:
Master switch
(2) ... Part 725:
Single-pole fusing of
circuits
(3) Electrical isolation by
transformer
recommended
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... Part 1:
Circuit breaker
... Part 1:
•
In the case of a grounded
secondary circuit: Provide
single-pole protection
• Otherwise: Provide all-
pole protection
Electrical isolation by
transformer mandatory
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5-17