BEKA BA337E-SS, Manual

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The BA337E-SS EC-Type Examination Certificate
specifies that the equivalent capacitance and
inductance of pulse input is:
Ci = 2nF
Li = 4µH
To determine the maximum permissible cable
parameters these figures should be subtracted from
the maximum permitted output parameters Lo and Co
specified by the certificate for the flowmeter
connected to the totaliser's pulse input terminals. The
totalisers pulse input equivalent capacitance and
inductance are small and unlikely to make a
significant difference to the allowable cable
parameters.
3.5.2 Flowmeter sensors that require energising
Flowmeters with switch contacts, proximity detector or
open collector outputs require energising which is
achieved by linking Rate Totaliser terminals 3 and 4
together as described in section 3.5. When
energised, the output parameters of the pulse input
terminals 5 and 6 are:
Uo = 10.5V dc
Io = 9.2mA dc
Po = 24mW
These output parameters do not comply with the
requirements for
simple apparatus and should be
considered when assessing the safety of the
flowmeter connected to the totaliser pulse input.
Any certified intrinsically safe flowmeter may be
connected to a BA337E-SS energised input providing
that:
a. The flowmeter is a certified intrinsically safe
device having input parameters equal to or
greater than:
Ui ≥ 10.5V dc
Ii ≥ 9.2mA dc
Pi ≥ 24mW
or complies with the requirements for
simple apparatus.
b. The flowmeter and associated wiring can
withstand a 500V rms insulation test to earth.
c. The flowmeter is located in the same hazardous
area as the BA337E-SS.
d. Minimum operating voltage of a flowmeter
incorporating a NAMUR compliant proximity
detector is less than 7.5V.
The maximum capacitance and inductance that may
be safely connected to the energised pulse input
terminals 5 & 6 (terminals 3 & 4 linked) is:
Co = 2.4µF
Lo = 200mH
This is not restrictive as the combined capacitance
and inductance of most sensors and the connecting
cable will be less than this.
3.6 Remote reset terminals
The BA337E-SS total display may be reset to zero
by connecting the external reset terminals RS1 and
RS2 together for more than one second. The two
reset terminals have the following input and output
safety parameters:
Uo = 3.8V dc
Io = 1mA
Po = 1mW
Ui = 28V dc
Ii = 200mA dc
Pi = 0.84W
The equivalent capacitance and inductance between
them is:
Ci = 0
Li = 0
The maximum cable capacitance and inductance
that may be safely connected between the reset
terminals RS1 and RS2 is:
Co = 40µF
Lo = 1H
The reset terminals may be directly connected to
any mechanically operated switch located within the
same hazardous area as the BA337E-SS Rate
Totaliser. The switch and associated wiring should
be able to withstand a 500V rms insulation test to
earth.
If the reset switch is required in the safe area a
Zener barrier or intrinsically safe relay is required to
transfer the contact closure into the hazardous area.
A diode return barrier is not suitable for this
application. Almost any intrinsically safe relay with
certification permitting the contacts to be connected
to equipment in the hazardous area may be used.
Alternatively the BA337E-SS may be configured so
that the total display is reset to zero when the
&
and
*
push buttons are operated simultaneously
for more than two seconds. See 6.19
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