Incorrect Dew Point Display - GE Optica Operator's Manual

Incorrect Dew Point
Display
Maintenance
If the dew/frost point reads incorrectly, first check the standard
preventive maintenance items:
1. Clean the mirror (see Cleaning the Sensor Mirror on page 7-1).
2. Balance the sensor optics (see Balancing the Sensor Optics on
page 7-2).
An alternative method for checking the accuracy of the unit's
electronics is to use a precision resistance decade box in place of the
platinum thermometer. Wire the decade box to the unit's sensor
connector as shown in Figure 25, and verify that the resistance
settings shown in the table produce the temperatures shown.
HIGH LOW
Resistance
Decade Box
RX100
RX10
RX1
RX0.1
RX0.01
Figure 7-2: Using a Resistance Decade Box
Optica
J
1123HK
K
Sensor
T
Cable
L
Connector
Optica
3
D2
15
Sensor
4
Cable
14
Connector
Resistance Table
Din Ty pe 100 Ohms at 0°C 0.385 Ohms/°C
Resistance Display Reading
Ohms °C (±0.1)
76.33 –60.0
96.09 –10.0
100.00 0.0
103.90 10.0
123.24 60.0
January 2006
°F (±0.2)
–76.0
14.0
32.0
50.0
140.0
7-7