KROHNE OPTISONIC 3400 Ex EN - Manual (Page 19)

ELECTRICAL CONNECTIONS
4
19
OPTISONIC 3400
www.krohne.com 10/2013 - 7312472200 - AD EX OPTISONIC 3400 -en- R02
4.1 General
The OPTISONIC 3400 C(/i) -Ex compact flowmeter and UFC 400 F(/i) -Ex signal converter
(separate version) must be incorporated in the equipotential bonding system of the installation.
This can be established internally by connection of the protective earth (PE) conductor of the
mains supply system to the internal PE clamp, or externally, by connecting a separate
equipotential bonding conductor to the external U-clamp terminal (size M5) at respectively the
flange of the mounting support (in case of compact instruments) or at the mounting device (for
signal converters in separate version). A separate bonding conductor must have a cross-
sectional area of at least 4 mm
2
.
The display cover seals the electronics compartment of the converter housing and provides type
of protection “flameproof enclosure”. The terminal compartment is default in type of protection
“
increased safety” ("Ex e") and can optionally be performed as flameproof enclosure ("Ex d").
The threaded joints formed by the covers and housing are a tight fit due to the requirements for
type of protection “flameproof enclosure”. Screw the covers on and off with care and never use
excessive force !
Keep the screw-threads free of dirt and well-greased (e.g. with PTFE grease). The grease will
help to prevent the threads from locking due to corrosion.
To unscrew the covers, first release the interlocking devices (one at each cover). Therefore
unscrew the M4 head screw with internal hexagon socket set using a No. 3 Allen key until the
interlocking device can be turned. After the covers are screwed back onto the housing, make
sure that the interlocking devices are properly refitted.
WARNING!
Allow the electronics to de-energize before opening the electronics compartment of the flow
converter housing. Wait at least 35 minutes for T6 and 10 minutes for T5 before opening.
Figure 4-1: Electrical connections
1 Unscrew interlocking head screw
2 Turn cover counterclockwise and remove
3 Open / close safety lid of mains supply section
4 Mains supply & signal / data terminals