Operation - Dräger PEX 3000 Manual Del Usuario

Operation

– Press the (▲+▼) keys and – depending on the transmitter type – apply the
recommended test gas concentration (see table) at a flow rate of approx.
0.5 L/min via the calibration adapter.
– Wait until the reading has stabilised (max. 3 min) and press the (▲+▼) keys
to calculate the necessary internal amplification of the transmitter. The
display shows the measured value with the newly calculated amplification
factor; however, this has not yet been saved. The original amplification
factor is restored if the calibration function is automatically exited by waiting
for more than 4 minutes in this status.
NOTICE
After sensor replacement, the internal amplification of the transmitter can
initially be set so high that the measured value can no longer be displayed. The
display will then show "99" or "9.9". In this case, press the keys (▲+▼) to
recalculate the necessary internal amplification, save it, and repeat the span
calibration.
– Press the (▲+▼) keys. This finally saves the newly calculated amplification.
The display shows a reference value for the sensitivity (span) of the sensor
(constantly amplified bridge signal). If this reference value is lower than 10 it
is displayed with a decimal point.
– The actual sensitivity of the sensor in mV per %LEL can be obtained by
multiplying the reference value by a factor 2 and dividing it by 100 (or for the
type XTR 0010, dividing it by 10), e.g.:
– If, after calibrating the type XTR 0000 with 52 %LEL propane, a
reference value of 45 is displayed, the actual sensitivity of the
DrägerSensor PR M DQ for propane is 45 * 2 / 100 = 0.9 mV/%LEL.
– If, after calibrating the type XTR 0010 with 4.4 %LEL ethanol, a
reference value of 32 is displayed, the actual sensitivity of the
DrägerSensor LC M for ethanol is 32 * 2 / 10 = 6.4 mV/%LEL. This value
is higher by a factor of 5 than for the DrägerSensor PR M DQ because of
the internal amplification of the DrägerSensor LC M.
– The reference value and/or the actual sensor sensitivity should always be
recorded in mV/%LEL for test purposes.
NOTICE
If the reference value is less than half the value recorded during commissioning
of the sensor or if the measured value does not stabilise within 3 minutes, the
sensor should be replaced (see "Replacing the sensor", page 42).
– Press the (▲+▼) keys to exit the span calibration.
– Press the ▲ key twice to return to measuring mode. The flashing point on
the bottom right is deactivated.
4.4.2.3 After completing the calibration
– The display shows the current gas concentration in %LEL and the
transmitter once again emits the concentration-dependent 4 to 20 mA
signal.
– Replace the upper part of the housing, ensuring that the atmosphere is free
of dust and fasten the cover screws.
4.5 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:
– Zero-point undercut by more than 5 %LEL or
1 %LEL
– Electronic fault
– Broken cable or short-circuit in the sensor cir-
cuit
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
Dräger PEX 3000