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

Troubleshooting Humidity Sensors

The humidity sensor is not protected against reversed polarity. Check
carefully when connecting the device or damage can result.
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.
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 27.
4. Using a calibrated multi-meter, measure the actual
voltage across the yellow and white sensor leads.
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.
Wire color definitions:
• White = ground
• Yellow = output VDC
• Blue = supply VDC
Table 27: Humidity Versus Voltage
RH (%) VDC (mV)
10 1330
15 1475
20 1610
25 1740
30 1870
35 1995
40 2120
45 2235
50 2360
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CAUTION
RH (%) VDC (mV)
55 2480
60 2600
65 2730
70 2860
75 2980
80 3115
85 3250
90 3390
95 3530
Troubleshooting Carbon Dioxide
(CO ) Sensors
2
The UVC is configured to use a 0–2000 PPM, 0–10 VDC,
single beam absorption infrared 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 (AI-14).
2. Using some other calibrated CO
CO reading at the sensor location.
2
3. Use the CO reading from Step 2 to determine the
2
expected sensor voltage from Table 28.
4. Using a calibrated multi-meter, measure the actual
voltage across the lead removed from AI-14 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
consult the factory for information on obtaining calibration
equipment and instructions.
Table 28: CO
Versus Voltage
2
CO (PPM) VDC (V)
2
300
400
500
600
700
800
900
1000
63 OM 1280-2 • MICROTECH UNIT CONTROLLER
Diagnostics and Service
sensing device, take a
2
sensor requires calibration,
2
CO (PPM)
2
1.5 1200
2.0 1300
2.5 1400
3.0 1500
3.5 1600
4.0 1700
4.5 1800
5.0 1900
VDC (V)
6.0
6.5
7.0
7.5
8.0
8.5
9.0
9.5