Emergency-Off Relay Contact In The Output Circuit - Siemens S7-300 Installation Manual

$SSHQGL[
  +RZ WR 3URWHFW 'LJLWDO 2XWSXW 0RGXOHV DJDLQVW ,QGXFWLYH 6XUJH
9ROWDJH
,QGXFWLYH VXUJH YROWDJH
Overvoltage occurs when inductive devices are switched off. Examples are relay
coils and contactors.
,QWHJUDWHG VXUJH DUUHVWHU
S7-300 digital output modules are equipped with an integrated surge arrester.
$GGLWLRQDO RYHUYROWDJH SURWHFWLRQ
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.
([DPSOH
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.
12-26
PS
CPU
SM SM SM SM SM SM
S7-300 Automation System, Hardware and Installation: CPU 312IFM - 318-2 DP
Contact in the output circuit
Inductivity requires circuiting
A5E00203919-01