Table of Contents
Advertisement
Minor Maintenance of
Sensor Optics
Cleaning and Balancing
the Sensor Mirror
Maintenance
Periodically inspect and maintain the sensor optics as described in the
following chapter. These procedures can be performed at any time,
but are only necessary when the Service indicator appears on the
status display, indicating that service is required.
Under normal conditions, the system is self-checking and self-
balancing. However, there are occasions when particulate matter and
water-soluble contaminants reduce sensor mirror reflectance and
system accuracy (see Contamination on page 3-6). Three features of
the OptiSonde system allow users to monitor and adjust the mirror:
•
The balance indicator (shown in Figure 5-1 below) provides a
graphic display of how much light is received by the mirror's
photodetector. It is also an indicator of the dew layer thickness.
This indicator increases and decreases in digital steps.
•
The bias screw adjusts the light signal received by the reference
photodetector and is used as a "coarse adjustment."
•
The automatic balance, or PACER cycle (discussed on page 1-6),
electronically fine tunes the optical balance between the IR
emitters and reference photodetectors.
In operation, the position of the balance indicator will depend on the
level of humidity and the sensor used. As the humidity changes, the
chilled mirror system will seek to establish control.
As contaminants deposit on the mirror, the balance indicator will
increase, as will the dew point readings. The
cleaning and balancing (followed by the
the contamination.
Note: If the mirror is severely scratched or pitted, you may not be
able to balance it. It may be replaced in the field, as discussed
on page 5-5. For industrial applications, GE Sensing
recommends the solid platinum mirror.
Menu: x
e
mbar
Balance
Indicator
T
°C
a
Figure 5-1: Balance and Status Indicator on OptiSonde Display
October 2007
PACER
cycle or manual
PACER
cycle) will mitigate
Auto Cycle
Indicator
6.0179
+25.09
14:33
Status
5-1
Advertisement
Table of Contents
