3. APPLICATIONS
3.1 Flow transmitter loops
A BA554E Rate Totaliser may be connected in
series with almost any 4/20mA flow loop and
calibrated to display the rate of flow and total flow.
Fig 2 illustrates a typical applications in which a
BA554E Rate Totaliser is connected in series with
a 2-wire flow transmitter.
Fig 2 Typical flow loop
The loop must be able to tolerate the additional
1.2V required to operate the Rate Totaliser. This
increases to 5.0V if the Rate Totaliser includes an
option backlight which is loop powered.
3.2 Resetting the total display to zero
The BA554E total display may be reset to zero by
momentarily connecting the reset terminals RS1
and RS2 together with a resistance of less than
1k
Ω
as shown in Fig 2.
Note:
The negative reset terminal RS2 is internally
connected to the negative 4/20mA input
terminal 3.
The total display may also be reset to zero by
operating the totalisers
▲
and
▼
push buttons
simultaneously for more than two seconds. See
section 5.17
3.3 Remote flow indication
A BA554E may be driven from any 4/20mA signal
to provide a remote indication of rate and total flow.
Again it is necessary to ensure that the voltage
capability of the 4/20mA signal is sufficient to drive
the Rate Totaliser which requires 1.2V rising to 5V
if the optional backlight is loop powered.
Fig 3 shows a typical application.
Fig 3 BA554E providing remote display
of rate & total flow.
5
