Teledyne 3000ZA - Trace oxygen analyzer - Manual (Page 59)

Trace Oxygen Analyzer Operation
Teledyne Analytical Instruments 47
To set the other parameters use the __ arrow keys to move the
blinking over to the desired parameter. Then use the __ arrow keys to
change the parameter.
Once the parameters for alarm 1 have been set, press Alarms again,
and repeat this procedure for alarm 2 ( AL–2 ).
To reset a latched alarm, go to Dft– and then press either _ two
times or _ two times. (Toggle it to Y and then back to N.)
—or—
Go to Ltch– and then press either _ two times or _ two times.
(Toggle it to N and back to Y.)
4.6 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 = 0–10 ppm
Med = 0–100 ppm
High = 0–250 ppm.
The Model 3000ZA is set at the factory to default to autoranging.
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 concentration falls to
below 85% of 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 autoranging 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 current output).
However, the digital readout and the RS-232 output of the
concentration are unaffected by the fixed range. They continue to read
accurately with full precision. See Front Panel description in Chapter 1.
4.6.1 Setting the Analog Output Ranges
To set the ranges, enter the range function mode by pressing the
Range button on the front panel.