KROHNE OPTISONIC 3400 Ex EN - Manual (Page 17)

CONNECTION OF SEPARATE SYSTEMS
3
17
OPTISONIC 3400
www.krohne.com 10/2013 - 7312472200 - AD EX OPTISONIC 3400 -en- R02
3.4 Equipotential bonding
3.4.1 Signal converter
The UFC 400 F...-Ex ultrasonic signal converter must always must always must always must always be incorporated within the
equipotential bonding system of the installation in the hazardous classified location. For this
purpose it must be connected to the external U-clamp screw terminal (size M5) of the UFC 400 F
converter.
The separate bonding conductor must be at least 4 mm 2 (11 AWG) or 2.5 mm 2 (14 AWG), in case
it is mechanically protected, see Clause 413 of HD 384.4.41 or IEC 364-4-41. Make sure that the
core of the bonding wire is properly mounted under the U-clamp of the PE-terminal and that the
screw is tightly fixed.
The intrinsically safe transducer circuits of the UFC 400 F signal converter are galvanically
isolated from earth, therefore an equipotential bonding conductor between the flow sensor
(grounded intrinsically safe transducer circuits) and the signal converter (floating-intrinsically
safe transducer circuits) does not have to be connected, but can be used if desired.
3.5 Signal cable connections (filed versions)
See the pictures below for details.
CAUTION!
When the ambient temperatures exceed 60
°
C / 140
°
F, the cables and cable gland used (for
connection of the UFC 400F/...) must be suitable for of at least 75
°
C / 167
°
F.
Electrical connection - Standard version
Figure 3-1: Connect the cables in the connection box of the flow sensor