Comparing Mechanical / Ultrasonic Wind Sensors

Introduction

Mechanical cup and vane (or rotor and vane) wind speed and direction sensors are the traditional instruments for measuring the wind (first 2 images). Additionally in recent years ultrasonic anemometers (third image), which measure both wind speed and direction with a single measuring head without any moving parts, have been developed as the high tech alternative.

Both technologies have their place and the list below is offered as a guide to help choose the most suitable method for your application.

A mechanical wind sensor can be cost-effective and the right choice where:

- a tight budget has to be met
- there is a large volume requirement and price is a serious issue
- to have visually moving parts are an advantage
- a replacement is required to match an existing mechanical system
- it is to be used with an existing logger or ancillary equipment
- output directly to a PC is NOT required
- only wind speed measurements are required
- only wind direction measurements are required
- data does not need to be logged or archived
- a shorter life expectancy is not an issue
- servicing is not an issue

Ultrasonic anemometers differ from mechanical sensors in having:

- no moving parts to repair or replace
- no maintenance requirements
- greater accuracy especially at low wind speeds and in gusts
- easy interface / connection to existing systems
- digital and analogue outputs
- automatic, averaged or polled data output
- one single sensor for both the wind direction and wind speed
- instantaneous measurements eliminating overrun and low starting value errors

Although initially more expensive the ultrasonic anemometer may be the right choice where:

- vertical as well as horizontal wind measurements are required
- extreme accuracy is required
- the sensor is being sited at a remote location where access is limited
- servicing of the sensor is not desirable
- digital output directly to a PC is required
- a single instrument combining both wind speed and wind direction is preferred
- a sensor is frequently subjected to freezing conditions
- a sensor is frequently subjected to harsh or marine conditions
- a greater life expectancy is desirable
- an instantaneous response is required

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