Section 2 Functional Description
9 FT722 & FT742 (RS485) – FF & PM Sensors – User Manual
2 FUNCTIONAL DESCRIPTION
2.1 Technical Performance
Sensor Performance
1 & 2
Measurement Principle Acoustic Resonance (compensated against variations in temperature,
pressure and humidity)
Wind speed Measurement
FT722 FT742
Range 0-50m/s 0-75m/s
Resolution 0.1m/s 0.1m/s
Accuracy ±0.3m/s (0-16m/s) ±0.3m/s (0-16m/s)
±2% (16m/s-40m/s) ±2% (16m/s-40m/s)
±4% (40m/s-50m/s) ±4% (40m/s-75m/s)
Knots and km/h options available.
Wind Direction Measurement
Range 0 to 360 0 to 360°
Accuracy 2 RMS (within 10 of 0) 2 RMS (within 10 of 0)
4 RMS (beyond 10 of 0) 4 RMS (beyond 10 of 0)
Resolution 1 (both models)
Acoustic Temperature Measurement
5
Units Celsius, Fahrenheit or Kelvin
Resolution 0.1°
Accuracy ±2°C under the following conditions:
Wind speed between 5m/s and 60m/s
Temperature Difference < 10°C (Sensor Temp. vs Air Temp.)
Operating (air) temperature between -20°C and +60°C
Environment
Temperature Range -40 to +85C (operating & storage)
Humidity 0-100%
Altitude 0-4000m
Data I/O
RS485 Interface Digital RS485 (half duplex), galvanically isolated from power
supply lines and case
Format ASCII data, polled or continuous output modes
Data Update Rate Up to 10 measurements per second (10Hz)
Power Requirements
3
Supply Voltage 24VDC nominal (12V to 30VDC)
Supply Current (Heater off) 31mA (typical)
Supply Current (Heater on) 6A (max) – The heater is thermostatically controlled. Heater power
consumption will depend on the heater energy required to keep the sensor’s
temperature at a user determined set point. The heater is limited to 4A and
99W by the default software settings
4
.
Physical
Weight Flat-Front 320g (max). Pipe-Mount 350g (max. excluding adaptor)
Material Aluminium alloy, hard anodised
I/O Connector 5 way (RS485 option)
Mounting Method Flat-Front or Pipe-Mount options. Self-aligning, screw fixing
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