Electrical connection
16 - EN
TTH200
CI/TTH200-EN
4.6
Electrical interconnection in explosion hazardous areas
Depending on the safety requirements, special interconnections are required for use in
explosion hazardous areas.
Important
Observe the "Ex relevant specifications" chapter (see data sheet or operating instructions).
Intrinsic safety
The supply isolators/PLC inputs must feature intrinsically safe input protection circuits in order to
eliminate hazards (spark formation). The interconnection must be inspected. In order to provide
proof of intrinsic safety, the electrical limit values must be used as the basis for the EC type-
examination test certificates of the equipment (devices); this includes the capacitance and
inductance values of the cables. Proof of intrinsic safety is said to have been provided if the
following conditions are fulfilled when a comparison is carried out in relation to the limit values of
the equipment:
Transmitter
(intrinsically safe equipment)
Supply isolator/PLC input
(related equipment)
U
i
≥
U
o
I
i
≥
I
o
P
i
≥
P
o
L
i
+ L
c
(cable)
≤
L
o
C
i
+ C
c
(cable)
≤
C
o
Field (explosion hazardous area)
Control room (secure area)
A
B
+
-
+
-
A00096
Fig. 10
A Transmitter
B Supply isolator/PLC input with supply
4.6.1 Installation in explosion hazardous areas
Transmitters can be installed in all kinds of industrial sectors. Explosion hazardous areas are
divided into zones, meaning that a wide range of different instruments are also required. The Ex
relevant specifications are stipulated in the section titled " Ex relevant specifications ".
