BEKA BA384E, Руководство пользователя

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4.2.5 2-wire proximity detector input
Most certified intrinsically safe flowmeters
incorporating a NAMUR 2-wire proximity detector
may be directly connected to a BA384G input,
providing the input safety parameters of the
proximity detector are equal to or greater than the
output safety parameters of a BA384G input. i.e.
Ui ≥ 10.5V dc
Ii ≥ 9.2mA 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
BA384G and with the associated wiring be able to
withstand a 500V rms insulation test to earth.
The BA384G contains a configurable debounce
circuit to prevent false triggering. Three levels of de-
bounce protection are independently available for
each input. See section 6.7.
4.2.6 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 BA384G input configuration menu is a low
level voltage pulse input intended for use with an
intrinsically safe magnetic pick-off. When a BA384G
input is configured for
CoiL
it complies 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 flowmeter's Co and Lo specified on it's intrinsic
safety certificate, less the BA384G 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 BA384G and with the
associated wiring be able to withstand a 500V rms
insulation test to earth.
The BA384G contains a configurable debounce
circuit to prevent false triggering of the instrument.
See section 6.7.
4.2.7 Voltage pulse input
Two voltage pulse input ranges are independently
selectable in the BA384G Rate Totaliser
configuration menu,
VoLt5 L
and
VoLt5 H
. When
configured for either of the voltage pulse ranges, the
input terminals 5 & 6 and 9 & 10 comply with the
requirements for
simple apparatus . This allows the
inputs to be connected to any certified intrinsically
safe voltage source within the same hazardous area
as the BA384G having output parameters equal to
or less than:
Uo ≤ 28V dc
Io ≤ 200mA dc
Po ≤ 0.84W
The BA384G Rate Totaliser may therefore be
directly connected to most certified intrinsically safe
flowmeters with a high level voltage signals.
The maximum permitted cable parameters will be
defined by the intrinsic safety certification of the
flowmeter less the BA384G input parameters which
are small and can often be ignored.
The BA384G contains a configurable debounce
circuit to prevent false triggering of the instrument.
Three levels of de-bounce protection are
independently available for each input, See section
6.7.
4.2.8 Remote reset
The BA384G 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 galvanic isolator is
required.
A BA384G may also be remotely reset from the safe
area. Any switch may be used but a galvanic
isolator is required to transfer the contact closure
into the hazardous area. Fig 4 illustrates how a
BA384G may be reset from both the safe and the
hazardous area.
Note: The BA384G 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 6.20