Servomex 07931001B, Operator'S Manual

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07931001B revision 6 © Servomex Group Limited. 2020
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4.11 Gain and phase settings
DC Gains 1 and 2 enable the signal to be optimized for the specific application; in
addition, the phase of the measurement signal and reference burst must also be
optimized. The gain setting may need to be changed due to long pathlengths, dust,
and beam divergence which can reduce the amount of laser energy reaching the
receiver.
To view photodiode DC Level
The DC photodiode level tells the user how much laser energy is being received by
the detector. Setting it to a specific level (by adjusting alignment and gain) can help
improve measurement accuracy and ensure transmission is maintained to an
acceptable level.
Figure 4-31: Gain and phase setting menu
DC Gain 1 and DC Gain 2 are typically set for each application and may need to be
changed during commissioning to obtain optimum performance.
Note: If the photodiode DC level is too high an error status will be raised and
the analyzer will report incorrect readings.
The photodiode DC level (DetSigV) must not exceed 3.5V DC .
In dusty processes, where the dust loads vary significantly, gain levels
set when dust loads are either very high, or very low can cause zero
detection (not enough laser energy) or saturation (too much laser
energy) when dust levels revert to normal. Review the application and
dust load variations and consult Servomex for advice on how to
maximize operation of the analyzer in these situations.
Note: Analyzer alignment is critical to obtaining a reliable measurement.
Excessive gain levels used to compensate poor alignment can cause
the measurement to become excessively noisy and reduce the LDL.
See sections 7.3.1and 7.3.2.
Note
You must use ‘Adjust Burst Phase Cal’ after changing the DC Gain
. Do
so with caution where process temperatures are above 900°C or gas
concentrations in the process are high. See section 4.11.4.
Level 1 Level 2 Level 3 Level 4 Level 5
Menu Set Up Manage Analyser Manage Current Config Phase/Gain Settings
Calibrate Manage Analyser Manage Current Config Service Mode Alignment LEDs
Data Log mA Input Save Current Config Phase/Gain Settings Alignment Lock Level
Alarms mA Output Restore Config Measurement Signal Photodiode DC level
Status Relay Setup Delete Config Physical Setup DC Gain 1
Set Up Filtering Detailed Setup DC Gain 2
Measurements Unit Select Transmission Level
Service X-Interference Raw Signal
Clipping AC Amplifier Gain
User Settings ABurst
Adjust Burst Phase Cal
Ref TransCal