Emergency-Off Relay Contact In The Output Circuit - Siemens CPU 313C Hardware And Installation Manual

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Overvoltage occurs when inductive devices are switched off. Examples are relay
coils and contactors.
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S7-300 digital output modules are equipped with an integrated surge arrester.
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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: Request information on relevant surge protection rating from the supplier of
inductive devices.
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The figures illustrates an output circuit requiring additional overvoltage protectors.
Figure 12-8 EMERGENCY-OFF relay contact in the output circuit
Refer also to the rest of the information in this section.
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Contact in the output circuit
Inductivity requires circuiting
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