The current IEC 61400-12-1 standard, which came into effect in 2005, establishes a minimum sensor rise of 15 times the diameter of the horizontal arm of side mount sensor booms. Mounting anemometers and wind vanes this distance above the boom ensures that the measurement uncertainty resulting from flow distortions around the boom arm are kept below 0.5% of the measured value.
With an aim toward further reducing measurement uncertainty, the current standard goes on to recommend that sensors be mounted at 25 times the boom diameter above the horizontal arm. The draft IEC 61400-12-1 standard, expected to be released in early 2017, has taken what was previously an optional recommendation and made it the new minimum sensor rise that the boom must achieve for compliance.
Our response has been to proactively develop a new boom design that achieves IEC compliance far in advance of the transition to the new standard. This will allow you to become accustomed to the new design on your own timeline, in a way that makes sense for your projects.
We are still temporarily offering the older 95” boom design so that nobody will be forced to retrofit towers with the new booms, which would disrupt measurement continuity for existing projects. However, when you are ready to adopt the new IEC standard, we’ll have a solution ready that achieves one of our core principles: easy-to-use measurement equipment that meets your requirements without going overboard and asking you to pay for things you don’t need.