Campbell CPEC300, Руководство по эксплуатации продукта

Страница: 136 / 175

Appendix F. CPEC300 Series Diagnostics
F-16
generator and the
Valve Module
inlet. Make sure there is no tee in
this connection (see Section 5.2.2 , Zero/Span
(p. 28)
). Finally, check the
flow setting of the dewpoint generator.
3. If the Zero Air valve (1) is selected and a scrub module is used, the
flow is controlled by the scrub module. The scrub module has a pump
to push the zero air through the valve module to the IRGA. A
CPEC300 system fully opens the flow control valve by setting
valveControl = 1 . The acceptable range for valve_flow is between
0.5 and 3.0 LPM. If a CPEC300 system is accessible, check the
indicator lights on the valve module as described above. Also check
the tubing connection between the scrub module and the valve module
inlet. Listen for the sound of the scrub module pump to make sure it is
running. Check the scrub module pressure
scrub_press
. This pressure
is measured at the outlet of the scrub pump. This pressure is normally
3 to 20 kPa. If the pressure is very high, it might indicate the Zero Air
valve or the proportion control valve is not open. If the pressure is
very low, it might indicate the pump is not running.
Bit 2: Valve Temperature
If the remainder of diag_cpec (after subtracting the numeric value for higher
bits that are set) is greater than 1, this means that bit 2 of diag_cpec is set. To
decode other diagnostic bits, subtract 2 from diag_cpec and compare the
remainder to the bit values below.
Bit 2 of diag_cpec indicates the valve module temperature is outside its
operating range. This check is performed only if the CPEC300 program is
configured to use a valve module, in which case the check is performed
continuously and Boolean variable valve_tmprOK is set accordingly.
However, the valve module temperature is ignored in EC mode (bit 2 of
diag_cpec is set only if it is relevant). If the valve module is outside its
operating range the zero/span sequence cannot be run, and the valves cannot be
selected manually. This protects the valves from possible damage.
To confirm the problem, verify that public variable valve_tmprOK = False .
This variable is set to True if the valve module temperature is within its
operating range (0 to 60 °C) and is set to
False
if it is outside this range.
The variable valve_tmprOK is not available for diagnosing a problem using
data saved in the output tables ( Flux or Zero_Span) . Instead, check the value
of ValveTmprOK_Avg . This is a floating point number that represents the
fraction of time (from 0 to 1) that
valve_tmprOK
is true during the averaging
period. A value of 1 indicates no problem with the valve-module temperature
at any time during the averaging period. A value of 0 indicates a valve module
temperature problem during the entire time.
To continue troubleshooting a problem with the valve module temperature,
check the measured temperature, valve_tmpr . If it is NAN , this indicates a
problem with the temperature measurement. Make sure the valve module cable
is connected to the side of the valve module.
Next, compare
valve_tmpr
to the operating range (0 to 60 °C). The valve
module will be disabled if it is too cold. The valve module has a heater that
turns on if valve_tmpr falls below 2 °C. If the valve module temperature is too
low, check the operation of the heater which is controlled by public variable
valve_heat_ON
. For diagnosing a problem using data saved in the output table