Doug Selsam’s Super Twin at Wulf Field

By Paul Gipe

Selsam’s SuperTwin had operated unattended from March 2008 through sometime in the spring of 2009.

We travel extensively and received a report that the turbine was not operating in March or April, 2009. In early May we visited the site and found a blown diode in the truck rectifier that Doug recommends.

The unit is more powerful than turbines I’ve tested before and this has required several time consuming and expensive modifications of our test equipment. These upgrades were never fully completed.

Because of other commitments, testing the turbine has not been a priority. Consequently, the tests remain incomplete. Below is a scatter plot of data points for one period this summer. This is not a power curve but the best I can do with my recording instruments and the time available.

We will remove the turbine something in June 2009. I have no plans to retest the turbine until my hardware is fully upgraded for a turbine of this size and I install new software.

My conclusion? The Super Twin is experimental, but it is an option for someone who likes to tinker with their wind turbines. I originally used a Whisper controller as Doug didn’t provide a controller. The Whisper controller was unsatisfactory so Doug sent me a truck rectifier bridge. This worked fine for several months until it overheated or otherwise failed. (The potting around one of the diodes melted.)

This is the first small turbine that I failed to complete a performance test on once the test was underway.

March 27, 2008

The SuperTwin was running unattended during several days of very high winds. Power was exceeding the limits of the instruments. To correctly measure the turbine’s peformance requires major modifications of the instrumentation and diversion loads that were never completed.

March 22, 2008

Nancy and I raised Doug Selsam’s Super Twin on a calm day and it’s ready to go.


March 13, 2008

Doug Selsam braved a particularly windy day (30-40 mph with gusts to 50 mph) to mount his Super Twin on one of the test towers at Wulf Field. Installation under such conditions is never easy.

We didn’t raise the tower because of the high winds.