Siemens SM 321 Referenzhandbuch Seite 5

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Supply lines with wire-end ferrules
Wire chamber
Ex i signal lines with wire-end ferrules
It can also happen that the minimum thread length is not adhered to between the different modules
(e.g. in mixed use of explosion-proof and standard modules). If the minimum thread length between
conducting parts of explosion-proof and standard modules is less than 50 mm, the following options
are available to you for adhering to the thread length between the modules:
1. Install the DM 370 dummy group (6ES7 370-0AA01-0AA0) between the relevant explosion-proof
and standard modules.
2. When the bus modules of the active backplane bus are used, you can also use the explosion-proof
isolating bar (6ES7 195-1KA00-0XA0).
•
In wiring the submodule, you must strictly separate the intrinsically safe lines from the non-intrinsically
safe. They must be laid in separate cable ducts.
•
The digital module must be operated with safe functional extra-low voltage. This means that these
modules may be subject to a voltage of no more than Um ≤ 60 V (DC) or 30 V (AC), even in the
event of an error.
All sources of voltage (e.g. internal 24 VDC load power supplies, external 24 VDC load power
supplies, 5 VDC bus voltage) must be connected with each other electrically in such a way that, even
if there are differences in potential, no voltage addition occurs at the different voltage sources and the
error voltage Um is not exceeded.
A5E00348721-03
Process connector
(screw connection)
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