6
Fig 3A Simplest circuit with one side of 4/20mA
current loop connected to earth
Fig 3B Two Zener barrier channels are
required if the 4/20mA current
loop can not be earthed at the
barrier busbar.
Fig 3C Galvanic isolator can be used with any
4/20mA current loop.
5. INSTALLATION
5.1 Location
The BA324D indicator is housed in a robust IP66
glass reinforced polyester (GRP) enclosure
incorporating an armoured glass window and
stainless steel fittings making it suitable for exterior
mounting in most industrial installations, including
off-shore and waste water treatment. Please
consult BEKA associates if high vibration is
anticipated.
The BA324D is surface mounting, but may be pipe
or stem mounted using the accessory kits
described in sections 9.7 and 9.8 of this manual.
The field terminals and the two mounting holes are
located in a separate compartment with a sealed
cover allowing the instrument to be installed
without exposing the display assembly.
Terminals 2 and 4 are internally joined and may be
used for linking the return 4/20mA wire - see Fig 2.
Similarly terminals 5 and 6 are internally joined and
may be used for linking cable screens. The
BA324D earth terminal is connected to the internal
EMC filters. For maximum radio frequency
interference rejection this terminal should be
connected to a local earth, or to a cable screen
which is earthed in the safe area. To prevent
circulating currents, cable screens should only be
earthed in the safe area.
The BA324D enclosure is fitted with a bonding
plate to ensure electrical continuity between the
three conduit / cable entries.
5.2 Installation Procedure
Fig 4 illustrates the instrument installation
procedure.
a.
Remove the instrument terminal cover by
unscrewing the two captive 'A' screws.
b.
Mount the instrument on a flat surface and
secure with screws or bolts through the two
'B' holes. Alternatively use one of the pipe or
stem mounting kits described in sections 9.7
and 9.8
c.
Remove the temporary hole plug and install a
cable gland or conduit fitting with required
ingress protection. If more than one entry is
required, replace one or both IP66 stopping
plugs with a cable gland or conduit fitting
having the required ingress protection.
d.
Connect the field wiring to the terminals as
shown in Fig 5.
e.
Replace the instrument terminal cover and
evenly tighten the two 'A' screws.
