II - DCE FEL ČVUT v Praze

Mechanical Configuration of an Automation System with SIMATIC S7 Ex Modules
1.7.6 Requirements of Terminals for Intrinsically Safe Type of Protection
1-26
These must be identifiable, for example by their type designation, and the
following constructional requirements must be observed:
Clearance in air and leakage path in accordance with
EN 50014/EN 50020 between two connection elements of different
intrinsically safe circuits must be at least 6 mm.
Clearance in air and leakage path between connection elements of each
intrinsically safe circuit and grounded metal parts must be not less than
3 mm.
Marking of connection elements must be unambiguous and easily
recognized. When a color is used for this purpose, it must be light blue.
The following must also be observed with regard to the use of terminals:
Connection terminals of intrinsically safe circuits must be at a distance of at
least 50 mm from connection elements or bare conductors of any nonintrinsically
safe circuit, or must be isolated from it by an insulating partition
or grounded metal partition. When such partitions are used, they must extend
at least by up to 1.5 mm from the housing panels, or must ensure a minimum
clearance of 50 mm between connection elements, measured about the
partition in all directions.
The insulation between an intrinsically safe circuit and the chassis of the
electrical apparatus or parts which may be grounded must withstand an
alternating rms voltage of twice the voltage value of the intrinsically safe
circuit, but at least 500 V.
I/O Modules with Intrinsically-Safe Signals
C79000-G7076-C152-04