BEKA BA337E-SS, Manual

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4.1.5 2-wire proximity detector input
Most certified intrinsically safe flowmeters
incorporating a NAMUR 2-wire proximity detector may
be directly connected to the BA337E-SS pulse input,
providing the input safety parameters of the flowmeter
(proximity detector) are equal to, or greater than the
output safety parameters of Rate Totaliser's pulse
input. i.e.
Ui ≥ 10.5V dc
Ii ≥ 8.2mA dc
Pi ≥ 24mW
and the minimum operating voltage of the flowmeter
(proximity detector) is less than 7.5V. The flowmeter
must be located in the same hazardous area as the
BA337E-SS and with the associated wiring be able to
withstand a 500V rms insulation test to earth.
The Rate Totalisers contain a configurable debounce
circuit to prevent false triggering. Three levels of
debounce protection are independently available.
See section 6.7.
4.1.6 Magnetic pick-off input
Flowmeters incorporating a magnetic pick-off to
sense flow will have a low level voltage output unless
the flowmeter incorporates an amplifier.
CoiL
in the
BA337E-SS input configuration menu is a low level
voltage pulse input intended for use with an
intrinsically safe magnetic pick-off. When a Rate
Totaliser is configured for
CoiL
and terminals 3 & 4
are not linked, the input terminals 5 & 6 comply with
the requirements for
simple apparatus allowing
connection to any certified intrinsically safe magnetic
sensor having output parameters equal to or less
than:
Uo ≤ 28V dc
Io ≤ 200mA dc
Po ≤ 0.84W
The maximum permitted cable parameters will be the
magnetic pick-off's Co and Lo specified on it's intrinsic
safety certificate, less the Rate Totalisers pulse input
parameters Ci and Li which are small and can often
be ignored.
The flowmeter must be located within the same
hazardous area as the Rate Totaliser and with the
associated wiring be able to withstand a 500V rms
insulation test to earth.
The Rate Totalisers contain a configurable debounce
circuit to prevent false triggering of the instrument.
See section 6.7.
4.1.7 Voltage pulse input
Two voltage pulse input ranges are selectable in the
BA337E-SS 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:
Uo ≤ 28V dc
Io ≤ 200mA dc
Po ≤ 0.84W
The Rate Totaliser input may therefore be directly
connected to 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 Totaliser contains a configurable debounce
circuit to prevent false triggering of the instrument.
Three levels of 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-SS 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-SS may
be reset from both the safe and the hazardous area.
Note: The BA337E-SS 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
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