Dräger PEX 3000 Manual Del Usuario página 39

5.4 Operation
In line with the gas concentration, the current loop produces a current between
4 and 20 mA, or
Current Meaning
0 mA Cable is broken or power supply has failed
1 mA Fault (see "Troubleshooting", page 39)
3.4 mA Calibration signal
3.8 mA to 20.5 mA Measured signal in normal operation
4 mA Measured signal zero-point
20 mA Measured signal full scale value
20.5 mA Over range by more than 3% of full scale value
5.4.1 Using a sensor membrane or the dust guard filter
Type XTR 0000/0001: To protect against moisture and dust and to reduce
sensitivity to wind and airflow, a sensor membrane can be attached to the gas
inlet of the DrägerSensor PR M DQ 68 14 140 (see order list, part number
83 26 840). The sensor membrane has no impact on the sensor's response
time (exceptions include long-chain vapours such as n-nonane). The influence
on the sensitivity is negligible. If the sensor membrane is attached, it must then
be recalibrated with the membrane. The sensor membrane must be checked
visually before each adjustment and replaced if necessary.
In the case of very significant dust accumulation and high aerosol exposure, the
DrägerSensor PR M DQ 68 14 140 can be used with a dust guard filter (see
order list, part number 68 10 537). This is simply pressed into the opening
before the sensor's wire mesh disc and is latching. The dust guard filter has no
impact on the sensor's response time (exceptions include long-chain vapours
such as n-nonane). The influence on the sensitivity is negligible. If a dust guard
filter is used, it must also be used during the adjustment procedure. The dust
filter should be replaced before adjustment.
The sensor membrane and dust guard filter must not be combined.
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6 Troubleshooting
Fault Cause
Display off Cable faulty
Transmitter cannot be Sensor faulty or poi-
calibrated soned
Measuring current is Transmitter signals a
1 mA, display shows E0, fault
E1, .... or E8
Error code Cause
E0 Supply voltage is below
12 V or above 30 V.
E1 Hardware error
E2 Memory error, error
when exporting calibra-
tion information
E3 Sensor not connected or
defective
E4 Sensor signal below –
5% LEL or lower than –
0.9% LEL
E5 Error during zero-point
calibration (e.g. offset
too high)
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Troubleshooting
Remedy
Check cable to the con-
troller.
Replacing the sensor.
See following table.
Remedy
Correction of the supply
voltage.
Replace 4 to 20 mA con-
verter module.
Repeat calibration pro-
cedure. If calibration fails
again: Hardware error.
Replace converter mod-
ule.
Check sensor connec-
tion and replace sensor,
if necessary.
Calibrate the zero-point
and sensitivity.
Check zero gas and
sensor and replace sen-
sor, if necessary.
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