II - DCE FEL ČVUT v Praze

Housing
Cables
Terminals
Protective device
Switch
Mechanical Configuration of an Automation System with SIMATIC S7 Ex Modules
I/O Modules with Intrinsically-Safe Signals
C79000-G7076-C152-04
The selected type of housing is characterized by the fact that it is able to
withstand explosions occurring inside the housing and that an explosive
gas/air mixture surrounding the housing is not ignited. In addition, the
surface temperature does not exceed the limit values of the temperature
classes. Cable glands that are protected against transmission of internal
ignition and isolated against the housing wall must be used for routing the
supply leads into the flameproof housing.
A housing with ”increased safety” is used as a terminal compartment. Special
screwed glands are used for the cable entries.
The housing must be certified by a testing authority to comply with the EEx
d type of protection and the relevant design requirements.
Explosion protection of the housing: EEx de II T5 .. T6.
The cables must comply with the DIN EN 50014 and DIN EN 50 020
standards for intrinsically safe circuits or with DIN EN 50039 for circuits
with ”increased safety”.
The cables for the assembly are to be installed in such a way that they are
endangered neither by thermal, mechanical nor chemical load or stress.
Note
The cables should be installed in cable conduits if necessary.
The terminal connectors for the power supply cable and the bus line should
always meet the requirements of the ”increased safety” tape of protection.
The claming points of the intrinsically safe circuits should always be
implemented according to the guidelines of ”Intrinsic safety”.
The assembly is connected to a 24 V DC supply circuit fed by a power
supply unit with safe electrical isolation. The supply circuit must be
protected by an appropriate circuit-breaker. This circuit-breaker is installed
outside the Ex zone.
The switch for enabling the system should comply with ”EEx de II T6” type
of protection.
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