BEKA BA334E, Руководство пользователя, Страница: 11 / 64

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4.1.3 Switch contact input
Any flowmeter with a mechanically or magnetically
activated switch contact located in the same
hazardous area as the Rate Totaliser may be
directly connected to pulse input terminals 5 and 6,
providing the flowmeter and associated wiring can
withstand a 500V rms insulation test to earth. Most
magnetically activated reed relays used in turbine
flowmeters comply with these requirements and the
requirements for simple apparatus. The BA334G
contains a configurable debounce circuit to prevent
false triggering. Three levels of de-bounce
protection are independently available.
See section 6.7.
4.1.4 Open collector input
Most certified intrinsically safe flowmeters with an
open collector output may be directly connected to a
BA334G input terminals 5 & 6, providing the input
safety parameters of the flowmeter (open collector)
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
The flowmeter must be located in the same
hazardous area as the BA334G and the associated
wiring should be able to withstand a 500V rms
insulation test to earth.
The BA334G contains a configurable debounce
circuit to prevent false triggering. Three levels of de-
bounce protection are independently available.
See section 6.7.
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 a BA334G 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
The minimum operating voltage of the flowmeter
(proximity detector) should be less than 7.5V. The
flowmeter must be located in the same hazardous
area as the BA334G and the associated wiring
should 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 BA334G 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. Three levels of de-bounce protection
are independently available. See section 6.7.
4.1.7 Voltage pulse input
Two voltage pulse input ranges are selectable in
the BA334G 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 Totalisers contain a configurable
debounce circuit to prevent false triggering of the
instrument. Three levels of de-bounce protection
are independently available. See section 6.7.