Siemens QFA3171 Outdoor Humidity and Temperature Sensor – 4–20 mA Outputs, 0–100% RH

General
The Siemens QFA3171 is a combined relative humidity and temperature sensor designed for outdoor air and demanding HVAC applications. It measures relative humidity from 0 to 100% RH and temperature using a Pt1000 sensing element.

The sensor provides separate active 4–20 mA output signals for humidity and temperature, enabling reliable integration with building management systems (BMS), HVAC controllers and industrial monitoring systems. It is powered by a 13.5–35 V DC supply and is designed for applications requiring current-loop signal transmission.

Features
- Combined relative humidity and temperature measurement.
- Separate 4–20 mA outputs for humidity and temperature.
- Humidity measurement range of 0–100% RH.
- Selectable temperature measuring ranges.
- Pt1000 temperature sensing element.
- Humidity accuracy of ±2% RH.
- Robust housing for demanding environmental applications.
- IP65 protection for the housing and IP40 for the measuring tip.
- Suitable for HVAC and building automation systems.

Key Specifications
- Brand: Siemens
- Model: QFA3171
- Manufacturer Part Number: BPZ:QFA3171
- Product Type: Combined humidity and temperature sensor
- Humidity Measuring Range: 0–100% RH
- Humidity Accuracy: ±2% RH
- Humidity Output: 4–20 mA DC
- Temperature Measuring Ranges: 0–50°C (factory setting), −35 to +35°C, −40 to +70°C
- Temperature Output: 4–20 mA DC
- Temperature Sensing Element: Pt1000
- Temperature Accuracy: ±0.6 K (15–35°C); ±0.8 K (40–70°C)
- Humidity Response Time: Approximately 20 seconds
- Temperature Response Time: Approximately 510 seconds
- Operating Voltage: 13.5–35 V DC
- Power Consumption: Maximum 1 W
- Display: No integrated display
- Electrical Connection: Screw terminals
- Connection: 2-wire current-loop outputs
- Protection Rating: IP65 (housing), IP40 (measuring tip)
- Dimensions (W × H × D): 80 × 144 × 39 mm