Operation Model
3020T
Teledyne
Analytical
Instruments
50
the number changes, speeds up the incrementing or decrementing.
(Remember, the setpoint units are always ppm O
2
.)
To set the other parameters use ENTER to blink the desired
parameter. Then use DOWN/UP to change the parameter.
Once the parameters for the alarm have been set, ENTER the
ALARM
function again, and repeat this procedure for next alarm.
To reset a latched alarm:
Go to
Dft–
and then assert either DOWN two times or UP two
times. (Toggle it to
Y
and then back to
N.
)
–OR –
Go to Ltch– and then assert either DOWN two times or UP two
times. (Toggle it to N and back to Y.)
Note: In this screen, ENTER moves you through the fields and
ESCAPE takes you back to the previous screen.
4.10 The RANGE Function
The
RANGE
function allows the operator to program up to three
concentration ranges to correlate with the DC analog outputs. If no
ranges are defined by the user, the instrument defaults to:
Low = 0–100 ppm
Med = 0–1,000 ppm
High = 0–10,000 ppm.
The Model 3020T is set at the factory to default to auto-ranging. In
this mode, the microprocessor automatically responds to concentration
changes by switching ranges for optimum readout sensitivity. If the
current range limits are exceeded, the instrument will automatically shift
to the next higher range. If the sample concentration falls below the full
scale of the next lower range, the instrument will switch to that range. A
corresponding shift in the DC percent-of-range output, and in the range
ID outputs, will be noticed.
The auto-ranging feature can be overridden so that analog output
stays on a fixed range regardless of the oxygen concentration detected. If
the concentration exceeds the upper limit of the range, the DC output
will saturate at 1 VDC (20 mA at the optional current output).