Table of Contents
Advertisement
Reversed Thermocouple
Wires
To check if the thermocouple wires
are reversed, display the thermo-
couple millivolts on the front panel
display. See Display section in
Setup key chapter for help.
If the millivolts are negative, the
thermocouple wires are reversed
to TC+ and TC- on the backplane
board.
Wiring Checks
Backplane Board Connections
TB2 - Pin 1
TB2 - Pin 2
TB2 - Pin 3
TB2 - Pin 4
TB1 - Pin 1
TB1 - Pin 2
Calibration Setup Checks
Check that the correct calibration
gas values have been entered into
the analyzer.
- From the Calibrate Key, select
the Cal Gas Value menu option
and check that the calibration gas
values entered match the analyzed
concentration of the cylinders.
Ensure that your calibration line is
not contaminated with such things
as pipe dope, cutting fluid, oil or
solvents. All these contaminants
produce hydrocarbon vapors that
interfere with the proper calibration
of your analyzer leading to lower-
than-expected oxygen readings.
6-6 | Thermox CG1000 Oxygen Analyzer
Thermocouple Compensation Circuit Check
To check the thermocouple you will need a digital volt meter.
-
First display the thermocouple millivolts on the front panel
display. The display should measure a positive voltage.
-
If the display measures a negative voltage, reverse the
wires leading to pins TC and TD on the backplane board.
-
To check the thermocouple compensation circuit, mea-
sure across capacitor C on the backplane board. If you
measure less than 15 volts, measure across connec-
tions TC- and Cell-. This should measure 12 mV (± 2 at
extreme ambient temperatures).
-
If you don't measure this voltage, replace th backplane
board.
Make sure all wiring connections between the control unit
and the sensor are terminated to the proper locations and
are seated properly. Ensure wires are not reversed and the
cable is not damaged.
Connector
Label
Cell +
Cell -
TC +
TC -
Furnace
Furnace
Calibration Gas Check
Are the calibration gas cylinders turned on? Are they empty?
Does the calibration gas bottle pressure have at least 500 lb.
of pressure?
Are the flow rate and delivery pressure of calibration gases
correct? They should match the flow rates for normal opera-
tion.
Are the PPM calibration gas cylinders made of aluminum and
not steel?
Are the calibration gas cylinders less than two years old?
Calibration Line Check
To test for contaminated lines, you must temporarily bypass
your current calibration line with a clean calibration line (directly
from the calibration gas cylinder to the sensor calibration inlet
port using a flow meter to set the proper flow) and compare the
response with that from the possibly contaminated line. The best
calibration gas to use for this check is O
Wire Connection
Cell Lead
No Connection
T/C Yellow Lead
T/C Red Lead
Furnace Lead
Furnace Lead
(No Polarity)
zero calibration gas.
2
Advertisement
Table of Contents
