9
7. MAINTENANCE
7.1 Fault finding during commissioning
If the BA304C fails to function during
commissioning the following procedure should be
followed:
Symptom
Cause
Solution
No display
Incorrect
There should be 1V
wiring.
between terminals 1 &
3 with terminal 1
positive.
No display
Incorrect
Check that a current
with 0V
wiring or
is flowing in the loop.
Between
no power
terminals 1
supply.
and 3.
Insufficient
Check supply voltage
loop voltage
and voltage drops
to operate
caused by all
BA304C.
components in
the loop.
No display
Indicator
Check that the three
with 4V
assembly
screws securing the
between
not correctly
indicator assembly
terminals 1
installed in
are tightened.
and 3.
enclosure.
BA304C
Positive
The BA304C has
displays 1
over-range.
been incorrectly
calibrated & is trying
to display a number
greater than 1999.
BA304C
Negative
The BA304C has
displays –1
over-range.
been incorrectly
calibrated & is trying
to display a number
less than -1999.
Unstable
4/20mA
Check loop supply
display.
input has a
voltage.
large ripple
7.2 Fault finding after commissioning
ENSURE PLANT SAFETY BEFORE
STARTING MAINTENANCE
Live maintenance is permitted on
intrinsically safe equipment installed
in a hazardous area, but only certified
test equipment should be used unless
a gas clearance certificate is available.
If a BA304C fails after it has been functioning
correctly, the following procedure should be
followed:
Symptom
Cause
Solution
No display
No power
Check that a current
with 0V
supply.
is flowing in the loop.
Between
terminals 1
and 3.
No display
Indicator
Check that the three
with 4V
assembly
screws securing the
between
not correctly
indicator assembly
terminals 1
installed in
are tightened.
and 3.
enclosure.
Unstable
4/20mA
Check loop supply
display.
input has a
voltage.
large ripple.
If this procedure does not reveal the cause of the
fault, it is recommended that the indicator
assembly is removed from the enclosure and
replaced. This can be done without disconnecting
power. If the replacement assembly functions, the
fault is within the original indicator assembly. If the
indicator is still faulty, it is likely that the fault is
within the enclosure assembly or field wiring.
7.3 Servicing
To simplify servicing BA304C indicators use a
common indicator assembly which may be
replaced on site. All BA304C indicator assemblies
without accessories are interchangeable.
To replace the indicator assembly remove the
three 'B' screws shown in Fig 4 which will allow the
assembly to be removed. If the instrument is fitted
with a backlight the fly-lead connecting it to the
terminals must be un-plugged. The replacement
indicator assembly may then be installed and the
enclosure reassembled.
Please note that an ATEX certified BA304C
indicator assembly must not be replaced by a non
ATEX certified BA304C assembly.
If after replacement of the indicator assembly the
instrument still does not function, it is likely that the
fault is within the protection components on the
terminal assembly. Terminal assemblies may also
be replaced on site providing that an instrument
with a backlight is fitted with a replacement board
including terminals 12 and 13.
We recommend that faulty instruments
and instrument assemblies are returned
to BEKA associates or your local BEKA
agent for repair