User Manual - PolyXeta
®
2 Detector with HL Sensor
for Refrigerant Gases - May_2020
Page
14
PolyXeta
is a registered trademark of MSR
Made in Germany
GAPX2_Freon_E_2020_05_18
Phone: +49 8531 9004-0 Fax: +49 8531 9004-54
Specification subject to change without notice
MSR-Electronic GmbH, Buergermeister-Schoenbauer-Str. 13, D 94060 Pocking
www.msr-electronic.de
6
Operating Modes
The instrument PX2-1 must only be opened under gas-free and voltage-free conditions.
The instrument PX2-2 should only be opened under gas-free and voltage-free
conditions.
After completion of work, the instrument must be closed again. The cover has to be
completely screwed in and secured with the locking screw against inadvertent
loosening.
6.1
Restart (Diagnostic and Warm-up Stage)
The device is designed so as to generally run through all internal device tests (diagnostics) in the PX2
module or in the sensor head after each power-up or processor reset before the measuring operation starts.
That means that the processor's internal components and the associated program and working memories as
well as the other components of the input and output units are tested. This process takes approximately 0.5
seconds.
When all diagnostics have been successful, the sensor element starts the warm-up phase.
The warm-up is necessary for the gas sensing element in the sensor head to assume a stable state after
return of the voltage without triggering a pseudo alarm. The duration of the warm-up phase depends on the
type of sensor used and can be read from the table 10.2
, “
Sensor Specification
” from the column “Warm
-up
periods”.
During warm-up, the yellow LED flashes every 2 seconds and "Power ON" appears in the display. The device
status during warm-up is given in Table 5.2
“
Status operating modes
”
.
The measuring operation starts after the end of the warm-up phase; the necessary diagnostic functions
continue to run in the background.
6.2
Measuring Mode
In normal operating mode =
measuring mode
there are no faults present, the gas concentration of the sensor
is continuously polled, checked for plausibility, output on the analog output and provided on the central bus.
The gas concentration is displayed on the built-in display, if available.
When the alarm evaluation is activated, only with alarm threshold > 0, the gas signal is checked with each
measurement cycle, if
≥ alarm threshold and
if exceeding, the alarm LED and the optional alarm relay are
triggered. If the value falls below the alarm threshold minus the set hysteresis again, the alarm is
automatically cancelled. With programmed self-hold function the alarm remains active until manual
acknowledgment.
The instrument continuously monitors itself, the measurement signal, the analog output, the alarm relay and
the communication to the sensor head.
If the measurement signal falls below the zero point, this will be tolerated up to a limit of minus 6 % of the
measuring range, the analog output signal drops down to 3 mA and there will be still no error generated.
Active dead band suppresses the 4-20 mA signal around the zero point. See chapter 11.5 "Deadband".
If the measurement signal exceeds the zero point, this will be tolerated up to a limit of plus 6 % of the
measuring range, the analog output signal increases up to 21 mA and there will be still no error generated.
