Ah. Was the generator shaft spinning freely during the last two windstorms? A stalled (or nearly stalled ~ 15 RPM) rotor will present a much higher wind load to the tower than a freewheeling one will...
Patrick Shoemaker Vector Data Systems LLC [email protected] office: (301) 358-1690 x36 http://www.vectordatasystems.com [email protected] wrote: > No, nothing like that. The generator had purely electrical failure, and > was stuck in the "brake" mode, where the shaft only spins at perhaps 15 rpm, > no matter the wind. > > I'd like to think I'm thorough, and yet I have found no reason for the tower > failure. We're putting it back up about 60% stronger. Well, when it > gets back, that is. > > > > > > > ++++++++++++++++++++++++++++++++ > <insert witty tagline here> > > ----- Original Message ----- > From: "Patrick Shoemaker" <[email protected]> > To: "WISPA General List" <[email protected]> > Sent: Wednesday, May 27, 2009 1:51 PM > Subject: Re: [WISPA] (topic change) sort of tower failure... > > >> Was the generator shaft seized? Variable pitch blades locked at the >> shallowest position? >> >> >> Patrick Shoemaker >> Vector Data Systems LLC >> [email protected] >> office: (301) 358-1690 x36 >> http://www.vectordatasystems.com >> >> >> [email protected] wrote: >>> Ok, so, two weeks ago, after having stood for 4.5 years, through 2, and I >>> mean TWO "century" wind storms, my generator tower failed on a very >>> normal >>> normal windy spring day. >>> >>> We took it the rest of the way down, cut it apart, looking for the cause >>> of >>> failure. >>> >>> And found none. No rust, no breaks, no corrosion, nothing. >>> >>> And found while it was down, that the generator windings and electronics >>> had >>> burnt themselves up, as well. >>> >>> A real head scratcher. All the "obvious" stuff ain't there. >>> >>> All we can think of is that there was some very localized freak >>> conditions >>> that did what the storm a year and a half ago could not do. The storm >>> then was so strong that about 1/3 of all homes suffered significant roof >>> damage. Fields migrated across roads. RV's tipped over. parked Semis >>> tipped over. metal buildings exploded. Wind velocities at the normal >>> stations set records. individual weather stations recorded high >>> hurricane >>> velocities. >>> >>> But our tower didn't bend or even show damage. >>> >>> But two weeks ago, where we had predicted "gusts" to 35 or 40 mph, caused >>> it >>> to fold. We had changed the blades on it a couple weeks before, on the >>> advice of the maker of the generator. They insisted that wind loading >>> was >>> within 1% of the original. >>> >>> So, we're re engineering it and back up it goes when the generator gets >>> back >>> from the maker (who is rebuilding it under warranty). >>> >>> I love a mystery. NOT. >>> >>> >>> >>> >>> >>> >>> ++++++++++++++++++++++++++++++++ >>> <insert witty tagline here> >>> >>> >>> >>> >>> -------------------------------------------------------------------------------- >>> WISPA Wants You! Join today! >>> http://signup.wispa.org/ >>> -------------------------------------------------------------------------------- >>> >>> WISPA Wireless List: [email protected] >>> >>> Subscribe/Unsubscribe: >>> http://lists.wispa.org/mailman/listinfo/wireless >>> >>> Archives: http://lists.wispa.org/pipermail/wireless/ >> >> -------------------------------------------------------------------------------- >> WISPA Wants You! Join today! >> http://signup.wispa.org/ >> -------------------------------------------------------------------------------- >> >> WISPA Wireless List: [email protected] >> >> Subscribe/Unsubscribe: >> http://lists.wispa.org/mailman/listinfo/wireless >> >> Archives: http://lists.wispa.org/pipermail/wireless/ > > > > -------------------------------------------------------------------------------- > WISPA Wants You! Join today! > http://signup.wispa.org/ > -------------------------------------------------------------------------------- > > WISPA Wireless List: [email protected] > > Subscribe/Unsubscribe: > http://lists.wispa.org/mailman/listinfo/wireless > > Archives: http://lists.wispa.org/pipermail/wireless/ -------------------------------------------------------------------------------- WISPA Wants You! Join today! http://signup.wispa.org/ -------------------------------------------------------------------------------- WISPA Wireless List: [email protected] Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/
