Siemens S5-135U/155U - Manual (Page 78)

4-12
System Manual
C79000-G8576-C199-06
4.1.4 Repair Guidelines
If measurements or testing become necessary whilst the unit is operational,
accident prevention regulations VBG 4.0 must be observed, especially the
permissible actions when working on active parts.
Only use tools that are suitable and approved for working on electrical
equipment.
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Repair of an automation system may only be carried out by the
SIEMENS customer service or by qualified personnel (see above).
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Always disconnect the AC power plug or open the isolating switch before
opening the unit. Wait at least 8 minutes before pulling out and opening a
power supply unit (see Section 4.2.3).
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Parts or components of a central controller may only be replaced by types
listed in Catalog ST 54.1 or in the appendix to this manual.
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Fuses may only be replaced by the same type.
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Instructions for maintenance of the individual components can be found
in the relevant chapters of this manual.
!
Warning
Unauthorized opening and improper repairs can result in death or serious
personal injury as well as considerable damage.
Central Controllers and Expansion Units Power Supply Units