Teledyne T100, Инструкция по эксплуатации, Страница: 114 / 404

Operating Instructions Teledyne ML - T100 UV Fluorescence SO2 Analyzer
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4.8.4.5. CURRENT LOOP OUTPUT ADJUSTMENT
A current loop option is available and can be installed as a retrofit for each of the analog
outputs of the analyzer (refer to Section 3.4.4). This option converts the DC voltage
analog output to a current signal with 0-20 mA output current. The outputs can be scaled
to any set of limits within that 0-20 mA range. However, most current loop applications
call for either 2-20 mA or 4-20 mA range. All current loop outputs have a +5% over-
range. Ranges with the lower limit set to more than 1 mA (e.g., 2-20 or 4-20 mA) also
have a -5% under-range.
To switch an analog output from voltage to current loop after installing the current
output printed circuit assembly, follow the instructions in Section 6.9.4.1 and select
CURR
from the list of options on the “Output Range” menu.
Adjusting the signal zero and span values of the current loop output is done by raising or
lowering the voltage of the respective analog output. This proportionally raises or lowers
the current produced by the current loop option.
Similar to the voltage calibration, the software allows this current adjustment to be made
in 100, 10 or 1 count increments. Since the exact current increment per voltage count
varies from output to output and from instrument to instrument, you will need to
measure the change in the current with a current meter placed in series with the output
circuit (refer to Figure 4-27).
Figure 4-27: Setup for Calibrating Current Outputs
IMPORTANT
Do not exceed 60 V between current loop outputs and instrument ground.