BEKA BA337E, 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 BA337E or BA338E input,
providing the input safety parameters of the proximity
detector are equal to or greater than the output safety
parameters of a BA337E or BA338E input.
The
(flowmeter) proximity detector input safety parameters
should be:
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
Rate Totaliser and with the associated wiring be able
to withstand a 500V rms insulation test to earth.
The BA337E and BA338E contain a configurable
debounce circuit to prevent false triggering of the
instrument. Three levels of de-bounce protection are
available.
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
BA337E and BA338E input configuration menu is a
low level voltage pulse input intended for use with an
intrinsically safe magnetic pick-off.
When a Rate
Totaliser input is configured for
CoiL
and terminals 3 &
4 are not linked, 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 be
the flowmeter'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 BA337E or BA338E and with
the associated wiring must be able to withstand a
500V rms insulation test to earth.
The BA337E and BA338E contain 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 BA337E and BA338E Rate
Totalisers 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 pulse input to be
connected to any certified intrinsically safe flowmeter
with a voltage output located within the same
hazardous area as the Rate Totaliser providing it has
output parameters equal to or less than:
Uo ≤ 28V dc
Io ≤ 200mA dc
Po ≤ 0.84W
The BA337E and BA338E Rate Totalisers may
therefore be directly connected to most certified
intrinsically safe flowmeters with a high level voltage
output.
The maximum permitted cable parameters will be
defined by the flowmeter's intrinsic safety Co and Lo
less the Rate Totaliser's pulse input parameters Ci
and Li which are small and can often be ignored.
The BA337E and BA338E contain a configurable
debounce circuit to prevent false triggering of the
instrument. Three levels of de-bounce protection are
available.
See section 6.7.
4.2.8 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 galvanic isolator is
required.
A BA337E or BA338E 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 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
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