17
6.9.1 AC rejection: FrE
WARNING
If the mains filter frequency is
changed, the rate display and the
internal references (if used) must be
recalibrated.
To provide maximum low frequency rejection the
internal digital filter may be set to operate at 50 or
60Hz to correspond with the local mains (line)
frequency. To change the frequency select 'FrE'
from the 'Cond' sub-menu and press
P
which will
reveal the current setting. The setting can be
changed by pressing the
Up
or
Down
buttons
followed by the
E
button to return to the sub-menu.
6.9.2 Calibration of internal references:
rEF
The BA354D contains two references representing
4 and 20mA. These are used in the 'SEt' function
which enables the rate display to be calibrated
without an external current calibrator. They are
also used in the 'C--P' function when the
P
push-
button is programmed to display the input current
in the operating mode. If either of these two
functions are used, the internal references should
be routinely calibrated against an external 4/20mA
calibrator connected to the input terminals of the
instrument. See section 8.4
To calibrate the internal references select 'rEF'
from the sub-menu and press
P
which will result in
a '.004A' prompt being displayed. Adjust the
external current calibrator to 4.000mA and again
press
P
. The instrument will display 'Ent' while the
4mA reference is being updated and will then
return to the '.004A' prompt.
To re-calibrate the 20mA internal reference, press
the
Up
button which will cause the instrument to
display '.020A'. Adjust the external current
calibrator to 20.000mA and again press
P.
The
instrument will display 'Ent' while the 20mA
reference is being updated and will then return to
the '.020A' prompt. This completes calibration of
the internal references, two operations of the
E
button will return the instrument to the 'Cond'
prompt in the main menu.
6.10 Resetting grand total: CLr. Gtot
The grand total is a separate sixteen digit counter
which duplicates the total display but is not zeroed
when the total display is reset to zero. The grand
total may be viewed in the
operating mode in two eight digit sections as
described in section 2.1 of this manual.
The grand total counter can only be reset to zero
from the 'CLr. Gtot' function in the main
programme menu. To zero the grand total
counter select 'CLr. Gtot' and press
P
which will
cause the instrument to display 'Clr. no' with 'no'
flashing. Continuously press the
Up
or
Down
push-buttons until 'CLr. YES' is displayed and then
press
P
which will result in a '0000' prompt. Using
the
Up
, and
Down
buttons and the
P
button to
move to the next digit, confirm the request by
entering the password 'SurE'. Note 'S' is entered
as '5'. Pressing
E
will then reset the grand total
counter to zero and return the instrument to the
'CLr. Gtot' prompt in the main menu.
WARNING
After resetting the grand total
counter to zero the old grand total
can not be recovered.
6.11 Timebase: t-bASE
Together with the total scale factor 'SCALE-t', this
function defines the arithmetic relationship
between the rate and total displays. The
timebase divides the rate display by 1, 60 or 3,600
depending upon whether the BA354D rate display
represents flow per second, per minute or per
hour. See Fig 6.
To check or change the timebase select 't-bASE'
from the main menu and press
P
which will reveal
the current setting. Pressing the
Up
or
Down
button will index though the following three options.
BA354D
Rate display
Represents
Flow
Select
In
t-bASE
menu
Total display
= rate display
divided by
Per second
tb – 1
1
Per minute
tb – 60
60
Per hour
Tb – 3600
3600
Select the required divisor and press
E
to return to
the main menu.
6.12 Function of the P push-button: C - - P
This parameter defines the function of the
P
push-
button when the BA354D is in the operating mode.
Either the input current in milliamps or the input as
a percentage of the span may be shown.
