Electrical Connections - ABB TTH300 Operating Instructions Manual

2.4.3

Electrical connections

Earthing
If, for functional reasons, the intrinsically safe circuit needs to
be earthed by means of a connection to the potential
equalization, it may only be earthed at one point.
Intrinsic safety installation check
If transmitters are operated in an intrinsically safe circuit, proof
that the interconnection is intrinsically safe must be provided
in accordance with IEC/EN 60079-14 as well as
IEC/EN 60079-25.
The supply isolators / DCS inputs must feature intrinsically
safe input protection circuits in order to eliminate hazards
(spark formation).
In order to provide proof of intrinsic safety, the electrical limit
value must be used as the basis for the EC-type examination
certificates for 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:
Transmitters
(intrinsically safe equipment)
U
i
I
i
P
i
L + L (cable)
i c
C + C (cable)
i c
Field (Ex area)
+
-
A
Fig. 1
A Transmitter B Supply isolator / DCS input with supply / Segment
coupler
8 OI/TTH300-EN Rev. D | TTH300
Supply isolator / DCS input
(related equipment)
≥ U
o
≥ I
o
≥ P
o
≤ L
o
≤ C
o
Control room (safe area)
+
-
B
Installation in a potentially explosive atmosphere
Transmitters can be installed in all kinds of industrial sectors.
Potentially explosive systems are divided into zones, meaning
that a wide range of different instruments are also required.
For this, pay attention to the country-specific guidelines and
certificates!
NOTICE
Ex relevant specifications must be taken from the EC-type
examination certificates and other relevant certificates that
apply in each case.
With transmitters for PROFIBUS PA and FOUNDATION
Fieldbus H1 applications, FISCO interconnection methods can
be used.
ATEX - Zone 0
Designation: II 1 G Ex ia IIC T6 Ga
Ex-area Zone 0
ia
J
A
Fig. 2
A Sensor B Transmitter in the housing with IP rating IP 20
C separator [Ex ia] D interface for LCD display
When using the transmitter in Zone 0, it must be installed in a
suitable housing with IP -rating IP 20. The input for the supply
isolator must have an [Ex ia] design.
When using the transmitter in Zone 0, you must ensure that
A10096
impermissible electrostatic charging of the temperature
transmitter is prevented (observe the warnings on the device).
As the user, it is your responsibility to ensure that the sensor
instrumentation meets the requirements of applicable
explosion protection standards.
Safe area
D
ia
ia
B C
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