This is a 33-minute video of an Enertech E44 running in overspeed in the Altamont Pass in the late 1980s. I had this video digitized for its historical content from a video cassette provided by Mark Haller from his collection when he worked for SeaWest in California’s Altamont Pass.
The E44 was one of the more successful American-designed wind turbines to come out of the US DOE wind program in the early 1980s. Like all the other American wind turbines of the period, the 40-kilowatt E44 operated downwind of the tower. The 44-foot (13.4 m) diameter laminated wood rotor was built by Gougeon Brothers of Bay City, Michigan. By 1985 there were nearly 500 Enertech E44s in California. Most were installed in the Altamont Pass and the San Gorgonio Pass. A few were also installed in the Tehachapi Pass, the Salinas Valley, and in Boulevard, California east of San Diego.
The video was filmed near SeaWest’s office in the Altamont Pass. Periodically the camera zooms in and then back out.
At 26 minutes into the video, the scene switches to another view of the same turbine.
At 26.30 minutes a truck enters the frame from right to left.
At 27.00 the scene switches again, providing a good view of several non-operating E44s showing their tip brakes.
At about 27.30 minutes heavy trucks hauling municipal waste cross the scene headed for Altamont’s landfill.
https://archive.org/details/enertech-e-44-wind-turbine-runaway-altamont-pass-mark-haller
At 31.30 minutes a truck passes in front of the camera. Less than 20 seconds later there’s a brief flash in the lower right hand corner of the video. Haller remembers this as the fuse on the 21 kilovolt line blowing. He doesn’t remember what popped the fuse. “Possibly a bird on the line,” he guessed.
Shortly thereafter, but not immediately Haller notes, the nearby turbines stop turning. They briefly were able to self-energize.
It was a windy day. Nearly all the Danish Micon 65 kW (15 meter) turbine in the near background, and US Windpower’s 56-100s in the far background are spinning merrily.
You can hear the E44’s gearbox whine as the rotor revs up from time to time; fully expecting it to fling its blades, but it continues to hang in there in a testament to the strength of Gougeon’s laminated wood blades.
You can also hear the occasional whop-whop characteristic of downwind turbines when they imitate helicopter rotors.
The video illustrates what happens when the generator, mechanical brakes, and the tip-brakes (spoilers) all fail. There’s nothing left to keep the rotor in one piece save for the strength of the blades, main shaft, and tower.
To the best of Haller’s recollection, the runaway occurred possibly subsequent to a retrofit of the E44s sometime in 1988-1989. This turbine may have been missed. Eventually the generator windings melted or were thrown from the generator rotor, locking the drive train in place with metal.
According to Haller, the original tip brake latch was improperly designed. When the induction generator failed and dynamic braking was lost, the rapid acceleration of the unloaded rotor kept the tip brakes engaged rather than deployed ultimately throwing the tips off the blades.
My thanks to Mark Haller for preserving this rare footage.
