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Posted by David Sherman [24.32.202.83] on Thursday, February 04, 2010 at 20:13:12 :
In Reply to: Re: I dunno about Tesla posted by Spence [66.226.44.47] on Thursday, February 04, 2010 at 19:36:37 :
Bridal Veil Falls sounds right. I drove past it once. Wished I'd had time to stop. I think there was a tourist train and mine tour setup there. I seem to remember the head on the Pelton wheel was insanely high, like 3000 feet.
I was lucky I once got to see the Nooksak Falls plant not just operating, but running independently of the grid, powering all the customers in the upper valley while the linemen worked on a section between the falls and the grid. It was built about 1915, used several Pelton wheels on one shaft, different numbers being turned on depending on the load and water available, and had a big open-frame Westinghouse generator with a flat belt driving its exciter. The excitation for the exciter came from a bank of car batteries, thus it could start from a dead stop and produce electricity without relying on any external source of power. Running flat-out it would produce 1.5 megawatts. Puget Power had recently put automatic controls on it so they didn't normally have to pay anyone to stay there, but an old guy was there to operate it that day just because of the special circumstances with the line work, and he was happy to show me around. He had put an electronic tachometer on the machine just to see how well the old fly-ball governor was working. It regulated the Pelton wheels by moving the needle nozzle in and out via a linkage that hydraulically amplified the governor signal using penstock pressure as the hydraulic "pump". The whole time I was there, the governor held the speed to between 400.0 and 400.1 RPM -- pretty good for a contraption that was "just" mechanical. When it came time for the line crew to quit and for him to go off-line just as the linemen threw the switch at their end to re-connect to the grid, the operation went off perfectly, the lights in the powerhouse briefly brightened as the generator adjusted to being unloaded (it had been running at a couple hundred kW all day just powering the town of Glacier and the houses up that way) and then came right back into regulation. He had found an antique synchroscope somewhere (before that they just had light bulbs to synchronize by) and used it to bring the the plant back into synchronization and connect it to the grid. Then he set it to run flat-out, putting all the juice it could make, which was around a megawatt that day, into the grid, locked it up and went home. Some time later, the automatic controls went berzerk and the whole thing burned itself up.
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