Teledyne 3000TB-XL - Trace oxygen analyzer - Manual (Page 59)

Trace Oxygen Analyzer Operation 4
4-19 Teledyne Analytical Instruments
4.6 The Range Function
The Range function allows the operator to program up to three concen-
tration ranges to correlate with the DC analog outputs. If no ranges are
defined by the user, the instrument defaults to:
Low = 0–1 ppm
Med = 0–10 ppm
High = 0–100 ppm.
The Model 3000TB
­XL 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 below 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 V dc (20 mA at the current output).
However, the digital readout and the RS-232 output of the concentra-
tion are unaffected by the fixed range. They continue to read accurately with
full precision. See Front Panel description in Chapter 1.
The automatic air calibration range is always 0-25 % and is not pro-
grammable.
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.
L—1 M—10
H—100 Mode—AUTO
Use the < > arrow keys to blink the range to be set: low (L), medium
(M), or high (H).
Use the
Δ∇ arrow keys to enter the upper value of the range (all ranges
begin at 0 ppm). Repeat for each range you want to set. Press Enter to
accept the values and return to Analyze mode. (See note below.)