FT702LT Ultrasonic Anemometer

Wind Speed and Direction | RS485 Digital Output| 3 Heaters

The FT702LT ultrasonic anemometer is the result of FT Technologies’ 10 years of experience in designing durable ultrasonic wind sensors for demanding environments. Users typically experience data availability of more than 99.9% as the ultrasonic anemometer keeps on working in many adverse environments where traditional sensors fail.

These high levels of availability are achieved through the use of Highly Accelerated Life cycle Testing during design, an extensive independent testing programme and a robust solid state design with no moving parts to degrade. The sensor is probably the most tested wind sensor in the world. It has passed over 28 independent tests including sand, dust, ice, vibration, drop, corrosion, hail and lightning protection.

Powered by a patented Acu-Res technology the FT702LT ultrasonic wind sensor delivers reliable wind speed and direction measurements for many years even in adverse conditions. 100% of the sensors are checked in a wind tunnel prior to shipment to insure that they will provide reliable service in the field.

FT702LT-V22 Ultrasonic Wind Sensor Specifications

  • Powerful Resonating Ultrasonic Signal
  • The Wind Sensor Signal is Inherently Compensated for Changes in Air Pressure, Temperature, and Humidity
  • Heavy Duty Construction with a Hard Anodized Body For Corrosion Resistance
  • Powerful De-Icing with 3 Internal Thermostatically Controlled Heaters (99 Watt)
  • Proven Internal Lightning Protection
  • 65,000 Sensors Installed Worldwide
  • Accurate Measurement of Wind Speed and Direction in Harsh Environments
  • Compact Size (2.76" x 3.07" or 70 mm x 78 mm)

Acoustic Resonance Measurement Principle

Acu-Res® is a patented solid-state (no moving parts) technology for measuring wind speed and direction. It uses an acoustic (ultrasonic) wave which is RESONATED inside a small cavity. This unique operating principle gives an unrivalled specification and many benefits, such as wide air velocity range, long life, high availability, small lightweight construction and exceptional sensitivity and accuracy. With no exposed parts

Acu-Res® gives a robust sensor that operates under extreme weather conditions. It has low power consumption and because of the Acoustic Resonance it provides built-in compensation against environmental factors known to affect other technologies. No other technology combines the many features of Acu-Res®.

Acu-Res has many advantages over alternative technologies and some of the more important are listed below:

  • Wide and scalable dynamic range Linear response of phase vs. air speed
  • Precise speed and direction indication
  • Wind direction accuracy independent of speed Inherently compensated against fluctuations in temperature pressure and humidity
  • Rugged, fully sealed construction for all weather operation and high availability
  • Reliable solid state (no moving parts) construction
  • Small, lightweight and easy to heat Low power consumption

Benefits of Acoustic Resonance Technology

Compact and Rugged

Acu-Res® technology only needs a small cavity to create and maintain acoustic resonance. Thus the sensor is compact and lightweight in comparison to other sensor technologies.

Because the volume of the sensor is minimized the entire housing can be readily and evenly heated, ensuring it remains ice free.

This Gives the Following Benefits:

  • A tough and rugged sensor that withstands large shocks, severe vibrations and extreme impacts
  • A low heater power is required to keep it ice free A long maintenance-free life is assured Simplified storage and handling and reduced transportation costs.
  • The unit has no moving parts and only one device is needed to measure both air speed and direction at the same time.

Reliable and Consistent Measurements

Acu-Res® Technology provides accurate, consistent and reliable data from all directions including inclined flow. Changes in air density and particulates in the air can affect the accuracy of cup anemometers. Ultrasonic time of flight instruments can have a lower accuracy due to precipitation with rain and dust reflecting or distorting the effective path of the sonic pulses.

The speed of sound in air varies as a function of temperature and to a lesser extent, humidity and pressure. Acu-Res® powered sensors adapt their transmission frequency to maintain resonance, thus automatically compensating for any environmental change. The quality of an air flow measurement can be assured as the ability of the sensor to maintain resonance is also monitored and reported by the Acu-Res® software.

FT702LT Ultrasonic Anemometer

FT702LT Ultrasonic Wind Sensor Performance

FT702LT-22 Range Sensor Accuracy Resolution
Wind Speed 0-50 m/s +/- 4% (15-50 m/s)
+/- 0.5 m/s (0-15 m/s)
0.1 m/s
Wind Direction 0° to 360° +/- 4° (Beyond +/- 10° Datum)
+/- 2° (Within +/- 10° Datum)
FT089 Pipe Mount Adapter

FT089 Pipe Mount Adapter

Part Number Pipe Size Material of Construction Dimensions
FT089 40-51mm O.D. Cast Aluminum

Acu-Res® Software

Every FT Technologies sensor has advanced Acu-Res® software built in. This does all the complex calculations required to derive wind speed and wind direction as well as:

  • Constantly adjusting the signal frequency of transducers to maintain resonance
  • Monitoring the quality of the data and flagging problems to the controller
  • Continuously checking the health of the sensor’s sub-systems and operating redundant systems
  • Dynamically controlling the heater power to maintain ice free operation with minimal power consumption
  • Implementing user parameters to configure the sensor to specific customers' needs, such as data filtering and configurable output settings

Acu-Res® software has been developed specifically for the air flow industry and optimized to deliver best performance for wind measurement applications.

Environmental Protection System

The Environmental Protection System

The Acu-Res® Environmental Protection System (EPS) has been designed to allow the sensor to work reliably under the most extreme conditions. The EPS helps to guarantee high data availability in all weather conditions.

The EPS Has Been Optimized To Minimize The Effects Of:

  • Lightning and EMC
  • Dust and sand
  • Solar radiation
  • Heavy rain
  • Salt water
  • Snow, freezing rain, ice, and hail
  • Physical impact
  • Vibration
  • Corrosion
  • Weathering and ageing

The EPS Ensures High Levels of Availability by Incorporating:

  • A hard anodized alloy body which is strong, corrosion resistant and transmits heat easily and evenly
  • A sealing system in the body and around the connector which keeps out sand, dust and water
  • Surge protection he of electronics to increase the sensor’s immunity to large voltage and current transients induced by lightning strikes
  • Three internal heaters which maintain the sensor at a constant temperature and stop it from icing up
  • Super hydrophobic coatings which helps keeps the sensor clean and dry
  • Highly Accelerated Life Cycle testing which qualifies the sensors to withstand extremes of temperature and vibration

The Acu-Res® technology platform and the FT702 series wind sensor are probably the most tested wind sensor technology in the world.