20
7. MAINTENANCE
7.1 Fault finding during commissioning
If a BA554D fails to function during
commissioning the following procedure should
be followed:
Symptom
Cause
Solution
No display
Incorrect wiring
There should be
1V between
terminals 1 & 3
with terminal 1
positive.
No display and no
voltage between
terminals 1 and 3
Incorrect wiring or
no power supply.
Insufficient loop
voltage to operate
instrument,
Check that a
current is flowing
in the loop.
Check supply
voltage and
voltage drops
caused by all
components in
the loop.
Rate display
shows flashing 1
Positive over-
range
The rate display
has been
incorrectly
calibrated and is
trying to display
a number
greater than
20500
Rate display
shows flashing -1
Negative over-
range
Input current is
less than 3.4mA
Unstable rate
display
4/20mA input has
a large ripple
content
Check loop
supply voltage
Unable to enter
the programme
mode
Incorrect security
code entered.
Enter correct
security code or
fit security link in
override
position. See
Fig 8
7.2 Fault finding after commissioning
ENSURE PLANT SAFETY BEFORE
STARTING MAINTENANCE
If a BA554D fails after it has been functioning
correctly, the following table may help to identify
the cause of the failure.
Symptom
Cause
Solution
No display and
no voltage
between
terminals 1 and
3
Incorrect wiring or
no power supply.
Check that a
current is flowing
in the loop.
Unstable rate
display
4/20mA input has
a large ripple
content.
Check loop supply
voltage.
Incorrect
calibration
Digital filter ‘FrE’
has been changed
after instrument
was calibrated.
Recalibrate rate
display.
Unable to enter
the programme
mode
Incorrect security
code entered.
Enter correct
security code or fit
security link in
override position.
See Fig 8
If this procedure does not reveal the cause of
the fault, it is recommended that the instrument
is replaced. Alternatively the electronic
assembly may be exchanged as described in
section 7.3
