BEKA BA368E, Manual

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4.1.8 Remote reset
The BA368E Counter total display may be remotely
reset to zero by connecting terminals RS1 & RS2
together for more than one second. Permanent
interconnection inhibits counting. Remote resetting
may be accomplished by any mechanically operated
switch located in the same hazardous area as the
Counter providing it and the associated wiring can
withstand a 500V rms insulation test to earth. No
Zener barrier is required.
A BA368E may also be remotely reset to zero 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 the BA368E total
display may be reset from both the safe and the
hazardous area.
Note: The BA368E can be configured to reset the
total display to zero when the
&
and
*
push
buttons are operated simultaneously for more than
three seconds - see 6.24.
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 certified galvanic isolator with output parameters
less than the input parameters of the BA368E having
the correct function may be used.
Fig 4 BA368E protected by galvanic isolators.
Fig 4 illustrates the basic circuit that is used for all
BA368E Counter installations protected by galvanic
isolators. For simplicity, connections for the pulse
output and the optional factory fitted alarms and
4/20mA output are shown separately in section 7
and 10 of this manual.
Alternatively the pulse source may be located in the
safe area. Fig 5 shows how an additional galvanic
isolator is used to transfer the signal to the BA368E
Counter in the hazardous area, although it may be
difficult to find isolators for some sensors.
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