Troubleshooting Humidity Sensors; Troubleshooting Carbon Dioxide (Co 2 ) Sensors - Daikin MicroTech II Operation And Maintenance Manual

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Troubleshooting Humidity Sensors

The UVC is configured to use a 0–100% RH, 0–5 VDC, capacitive humidity sensor.
Each sensor is calibrated according to the table shown.
The humidity sensor is not protected against reversed polarity. Check carefully when connecting the
device or damage can result.
Use the following procedure to troubleshoot a suspect sensor:
1. Disconnect the sensors output voltage lead from the UVC analog input.
2. Using some other calibrated humidity sensing device, take a humidity reading at the
sensor location.
3. Use the humidity reading from Step 2 determine the expected sensor voltage from
Table 23.
4. Using a calibrated multi-meter, measure the actual voltage across the yellow and
white sensor leads.
Wire color definitions:
White = ground
Yellow = output VDC
Blue = supply VDC
5. Compare the expected voltage to the actual voltage.
6. If the actual voltage value deviates substantially (more than 10%) from the expected
voltage, replace the sensor.
Table 23: Humidity versus voltage
RH (%)
10
15
20
25
30
35
40
45
50

Troubleshooting Carbon Dioxide (CO 2 ) Sensors

The UVC is configured to use a 0–2000 PPM, 0–10 VDC, single beam absorption infra-
red gas sensor. Each sensor is calibrated according to the table shown.
Use the following procedure to troubleshoot a suspect sensor.
1. Disconnect the sensors output voltage lead from the UVC analog input (xAI-3).
2. Using some other calibrated CO 2 sensing device, take a CO 2 reading at the sensor
location.
3. Use the CO 2 reading from Step 2 to determine the expected sensor voltage from
Table 24 on page 42.
4. Using a calibrated multi-meter, measure the actual voltage across the lead removed
from xAI-3 and ground.
5. Compare the expected voltage to the actual voltage.
6. If the actual voltage value deviates substantially (more than 10%) from the expected
voltage, replace the sensor.
In the unlikely event that the CO 2 sensor requires calibration, consult the factory for
information on obtaining calibration equipment and instructions.
CAUTION
VDC (mV)
1330
1475
1610
1740
1870
1995
2120
2235
2360
41
d
IaGnostICs and
RH (%) VDC (mV)
55 2480
60 2600
65 2730
70 2860
75 2980
80 3115
85 3250
90 3390
95 3530
s
erVICe
OM 752-4