Configuring Alarms; Testing Alarms/Relays; Interface Settings; 4-20Ma Interface - Dräger Polytron 8000 Serie Notice D'utilisation

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Interface settings

12.10.2 Configuring alarms

1. Select Settings > Instrument > Alarm > Alarm A1 or
Alarm A2 and confirm.
The current alarm threshold is displayed.
2. Apply settings and confirm the configuration steps
successively with Next.
a. Set value for alarm threshold.
b. Set alarm direction.
Rising The alarm direction is called rising, if the
gas concentration has to exceed a certain
value to activate an alarm.
Falling The alarm direction is called falling, if the
gas concentration has to fall below a certain
value to activate an alarm.
c. Set latching mode.
Latching Once the alarm threshold is reached, the
instrument will trigger the alarm. It will
remain in alarm status even if the gas con-
centration does not meet the alarm condi-
tion any more. To clear a latching alarm it
has to be acknowledged.
Non-latching The alarm status clears if the gas concen-
tration does not meet the alarm condition
anymore.
d. Set acknowledgement mode.
Acknowledge- Alarm relay and LED can be reset before
able alarm condition clears.
Non-acknowl- Alarm relay and LED can not be reset until
edgeable the alarm condition clears.
Pre-Acknowl- Alarm status is acknowledgeable before the
edgeable alarm condition clears. However, the alarm
relay and LED stay active until the alarm
condition clears.
e. Set the hysteresis mode.
The hysteresis function defines an interval where a
triggered relay maintains its status until the gas
concentration is outside the defined interval. Example:
Alarm threshold is set to 40 ppm and hysteresis to
3 ppm . The alarm stays active until the value falls
below 37 ppm. This prevents relays from chattering at
an alarm threshold.
When the direction of an alarm was changed (from
falling to rising or vice versa), the value of the
hysteresis must be checked and corrected again if
necessary.
 A confirmation screen shows all settings.
f. Select Confirm and confirm with OK.
✓ The new settings are saved.
26

12.11 Testing alarms/relays

These functions change the status of a relay and LED for test
purposes (e.g. to check the function of alarm devices
connected to the relay) and the symbol
exiting this function, the status of the relay and LED will
automatically return to their previous status.
1. Select Settings > Instrument > Alarm the desired alarm
condition and confirm.
Set Alarm A1 Simulates pre-alarm
Set alarm A2 Simulates main alarm
Set fault Simulates fault signal
2. Select Enable or Disable and confirm.
✓ If the function is activated, the fault relay is de-energized
and the 4 to 20 mA interface is set to the fault current. The
yellow LED is lit, the symbol for maintenance is shown.
13 Interface settings
For further information regarding the configuration of other
interfaces consult the relevant documents.
Interface
®
HART
®
PROFIBUS PA
TM
Foundation Fieldbus FF
Modbus RTU

13.1 4-20mA interface

The current output of the instrument during normal operation
is between 4 and 20 mA and is proportional to the detected
gas concentration.
®
Polytron 8xx0 uses different current values to indicate
various modes of operation. The factory default settings are
user adjustable for application specific requirements. This
follows the NAMUR recommendation NE43.

13.1.1 Full scale deflection

®
Polytron 8100 EC, 87x0 IR and 8200 CAT LC only
Some sensors offer an adjustable full scale deflection to limit
the measuring range for the 4-20 mA interface.
The full scale deflection (FSD) sets an endpoint within the
measuring range of the sensor. If the gas concentration
reaches this endpoint, the 4-20mA interface transmits 20mA.
Example: Required range 0 to 500 ppm CO (e.g. part number
6809605 default 300 ppm, range min/max = 50/1000
ppm).Select full scale deflection as 500 ppm. The analog
output will be linear between 4 mA = 0 ppm and 20 mA =
500 ppm.
Instructions for use
is displayed. After
Document
Technical Manual
®
Polytron 8000 series
9033848 / 9033845
9033782
9033783
9033781
®
|
Dräger Polytron 8000 Series