The 2 output channels can be selected to drive a full scale of either 0 to 20 mA or 4 to 20 mA to represent the parameter
that is selected in set-up functions 20.
Options:
1. 0-20 mA
2. 4-20 mA *
14. OUTPUT CHANNEL #2, 0-20mA or 4-20mA
The 2 output channels can be selected to drive a full scale of either 0 to 20 mA or 4 to 20 mA to represent the parameter
that is selected in set-up 23.
Options:
1. 0-20 mA
2. 4-20 mA *
15. SET CALIBRATION FACTOR FOR CHANNEL #1
The calibration of the 4-20 (or 0-20) mA outputs is done by reading back the output into the input and calibrating this
against a known standard. The standard however, may vary from Analyzer to Analyzer. To allow for this, a trim factor
has been provided to set the calibration of each channel for your particular Analyzer. These two values should only
have to be entered once for the life of the instrument, then the only calibration of the outputs should be to press the
‘AUTOCAL’ button every twelve months.
To determine the calibration factors, generate a full scale value to be sent to the output. eg. For Channel #1, if set-up
steps 21 and 22 were set for a full scale output of 0 to 10% oxygen, then generate input signals until the top line of the
display reads 10% oxygen. This is best done with the use of a Teledyne Analytical Instrumentssimulator test box, but
can also be achieved with a millivolt generator.
Read the output of channel #1 with a three and a half digit multimeter.
ie. The output should be 20mA.
Your meter could read 19.65mA.
In this case as the full scale current is low, increase the calibration factor by about 1% ie. Enter 101.0 %.
Press ‘AUTOCAL’ before leaving the ‘set-up’ mode.
A more accurate way determining the correct factor using the same example -
20.00 to 19.65 = 0.35
( 0.35/19.65 ) *100% = 1.8% error.
Enter the value of 101.8 into ‘set-up’ step 15, 4 to 20 mA #1 CAL, and press ‘AUTOCAL’ before leaving the set-up
mode.
NOTE
The accuracy of the output channels without trimming these factors is generally within 1% after using the ‘AUTOCAL’
procedure. In most cases the instrument can be used without this further trimming of the calibration.
16. SET CALIBRATION FACTOR FOR CHANNEL #2
Follow the procedure set in step 15 for Channel #2.
(It is convenient to use set-up steps 23 to 25 set to Sensor EMF, 0-100 mV.)
17. ENTER SERVICE YEAR
For a new ‘DATE OF LAST SERVICE’, enter the service ‘YEAR’. This can represent the last time the Analyzer was
serviced. It is recommended that the oxygen sensors be refurbished every two years.
18. ENTER SERVICE MONTH
Enter the current ‘MONTH’.
19. ENTER SERVICE DAY
End the current ‘DAY’ of the month. Altering these values will reset the ‘RUN TIME’.
20. TRANSMITTER OUTPUT CHANNEL 1
Select the type of output required from Channel 1. Linear is the most common output required. The low oxygen range
is used for application that have oxygen below 1000ppm (0.1%)
Options:
Teledyne Analytical Instruments 9070 Oxygen Analyzer Page 33
