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4.1.7 Voltage pulse input

Two voltage pulse input ranges are selectable in the
BA337E and BA338E Rate Totaliser configuration
menu,

VoLt5 L

and

VoLt5 H

. When configured for

either of the voltage pulse ranges and terminals 3 & 4
are not linked, the input terminals 5 & 6 comply with
the requirements for

simple apparatus

. This allows

the input to be connected to any certified intrinsically
safe flowmeter with a voltage output located in the
same hazardous area as the Rate Totaliser having
output parameters equal to or less than:

≤

28V dc

≤

200mA dc

≤

0.84W

The Rate Totaliser input may therefore be directly
connected

most

certified

intrinsically

safe

flowmeters with a high level voltage pulse output.

The maximum permitted cable parameters will be
defined by the intrinsic safety certification of the
flowmeter less the Rate Totalisers input parameters Ci
& Li which are small and can often be ignored.

The Rate Totalisers contain a configurable debounce
circuit to prevent false triggering of the instrument.
Three

levels

de-bounce

protection

are

independently available.
See section 6.7.

4.1.8 Remote reset

The Rate Totaliser's total display may be remotely
reset to zero by connecting terminals RS1 and RS2
together for more than one second.

Permanent

interconnection inhibits totalisation. Remote resetting
may be accomplished by any mechanically operated
switch located in the same hazardous area as the
Rate Totaliser providing the switch and the associated
wiring can withstand a 500V rms insulation test to
earth. No Zener barrier is required.

A BA337E or BA338E may also be remotely reset
from the safe area.

Any switch may be used but a

Zener barrier is required to transfer the contact
closure into the hazardous area which may be
combined with the supply barrier so that only one
package is required.

A diode return barrier is not

suitable for this application. Fig 2 illustrates how a
BA337E or BA338E may be reset from both the safe
and the hazardous area.

Note:

Both Rate Totalisers may be configured to
reset the total display to zero by operating the

and

push buttons simultaneously for

more than two seconds in the totalising mode
i.e. when the instrument is displaying flow.
See 6.19

4.2

Use with Galvanic Isolators

Galvanic isolators are probably the simplest
intrinsically safe interface to install as they provide
isolation and do not require a high integrity earth
connection.

Any galvanic isolator may be used with the BA337E
and BA338E providing it's certification is for use with
apparatus in the required Zone and gas group, and
it's output parameters do not exceed the input
parameters of the Rate Totaliser terminals to which it
is connected. It must also have the correct function.

Fig 4 BA337E or BA338E used with galvanic

isolators.

Fig 4 illustrates the basic circuit that is used for all
BA337E and BA338E installations protected by
galvanic isolators.

For simplicity, connections for

the pulse output and optional alarms and 4/20mA
output are shown separately in section 10 of this
manual.

The totaliser pulse source may be located in the
safe area as shown in Fig 5. An additional galvanic
isolator is used to transfer the signal to the rate
totaliser in the hazardous area, although it may be
difficult to find isolators for transferring some
flowmeter transducer outputs.