05 June 2012

IEC 61400-2 edition 3: small wind turbines (CDV)

One of the reasons I have blogged less over the last few years is that I have been contributing to the drafting of the third edition of the IEC 61400-2 small wind turbine standard, and that has taken up a noticeable amount of my personal discretionary time as well as some of our company time.

I am not alone in this effort and behind the scenes in many countries for the last three or four years many people have been contributing in a committee known as MT2, which is a sub-committee of the main wind turbine standards committee TC88 within the IEC international standards organisation.

There have been contributors from the UK, USA, Canada, Ireland, Spain, Sweden, Denmark, Korea, Japan, China, Taiwan, Australia, Greece, Italy, France, Netherlands, Germany, and Israel. The committee has worked in liaison with an IEA committee looking at small wind R&D areas (known as R&D task 27), and Ignacio Cruz (of CIEMAT, in Spain) and Trudy Forsyth (until recently at NREL, in USA) were the co-convenors and have kept this collective effort moving along smoothly. Many of the prominent people in the industry have given generously of their time to both these committees, and so too have many of the companies in the industry. The basic division of responsibility in the wind energy sector is that IEC looks after standardisation, and IEA acts as a vehicle for coordinating international R&D activities.

During the last fortnight the committee draft for vote (CDV) of IEC61400-2 was submitted to IEC and will soon be circulated out to the national committees (NCs) for vote, certainly by August 2012.

This is an important milestone for a document that is important for the small wind turbine industry. The process has been as important as the product, and it is no coincidence that during the last few years a dozen or so wind turbines have completed the certification process for AWEA/SWCC and BWEA/MCS, and nor is it a coincidence that these two certification schemes are essentially interoperable. The IEC 61400-2 ed 3 includes a lot of the experience gained from this over the last few years.

The cover page of a CDV includes the following text, "This document is still under study and subject to change. It should not be used for reference purposes." This means that it might still be tweaked. However if you are working in the small wind industry then it is probably worth contacting your national committee and asking to read a copy of the CDV. The foreword highlights some of the main areas of change and reads as follows:

International Standard IEC 61400-2 has been prepared by maintenance team 2 of IEC technical committee 88: Wind turbines.

This third edition cancels and replaces the second edition published in 2006.

This edition constitutes a technical revision. Numerous substantive changes have been made.
The most significant of these are:

 • the title has been modified to better reflect the scope;
 • restructured into part I (design evaluation) and part II (type testing) to harmonise use with  IEC 61400-22 conformity testing & certification;
 • caution provided regarding the use of simplified equations;
 • added annex on other wind conditions;
 • added annex on tropical storms;
 • added annex on extreme environmental conditions;
 • added annex on EMC testing;
 • added annex on dynamic behaviour;
 • duration testing requirements modified;
 • added annex on standardised format consumer label;
 • many minor changes and all known errata corrected.

As an example the existing BWEA small wind standard is about 20-pages. After reviewing it against the proposed IEC 61400-2 ed 3 (i.e. the CDV) it looks possible to compress the BWEA standard down to about 4 pages, most of which would simply be what I call "topping and tailing", which is an indication of the amount of learning that has been done by MT2.

One area that has definitely been resolved is that the upper size limit for "small wind turbines" has been confirmed as being a swept area of 200m2. During the process of writing the 3rd edition it was discussed that this might be increased and ultimately the decision was made to keep the limit unchanged at 200m2. There was a lot of debate over this, both within MT2 and within TC88, and the final decision was made very clearly by TC88 who are the ultimate arbiter on the subject. This means that "medium wind turbines" must use the IEC 61400-1 large wind turbine standard, and this is just beginning the process of drafting another edition. Within the -1 team many of the medium wind turbine companies are contributing to evolve a suitable outcome for turbines of 200m2 - 1000m2. If you or your business are involved in that size of turbine and wish to contribute you should contact you NC and ask to be placed in touch with the -1 committee. (The NC is ordinarily your country's national standards institute, so for example in the UK it is the British Standards Institute. If you are not sure who your NC are then email the IEC: http://www.iec.ch/ and they can tell you).

So .... maybe I'll get more of my weekends back. That might mean more blogs, who knows. I'm certainly working on trying to increase the amount of insulation in my house, to get my garden under control, and to try and get a bit of sailing and walking in with friends and family.

Thank you to everyone who has contributed in MT2 and task 27.

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