The HAER-data-pages provides a history of the C&O Canal and electricity as well as details for this dam and Dam #5.
These two photos show a variance in river levels.
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| AER WVA,2-SHEP.V,1--17 17. Credit PED. View of power house and dam from operator's house, looking toward Maryland. Note the absence of transformers adjacent to power house. Photo c. 1910. - Dam No. 4 Hydroelectric Plant, Potomac River, Martinsburg, Berkeley County, WV |
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| HAER WVA,2-SHEP.V,1--18 18. Credit JTL. View of power house and dam from operator's house, looking toward Maryland. |
Matt Pyle posted 4 of the 6 diagrams in HAER with the comment: "Still in operation in our southern fleet."
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| Dennis DeBruler commented on Matt's post Wow. I've seen horizontal turbine shafts before, but never a rope drive for an electric generator. HAER WVA,2-SHEP.V,1- (sheet 5 of 6) https://www.loc.gov/pictures/resource/hhh.wv0222.sheet.00005a/ via https://www.loc.gov/pictures/collection/hh/item/wv0222/ Matt Pyle: Its setup to run 2 rope sets for some reason, but we only run 1 set for some reason. They still have to teach the new guys how to splice the rope when it gets replaced. This print is old, they ended up adding the 3rd unit at this project. Dennis DeBruler: Matt Pyle Is the third unit also 500kw? |
Because the Potomac River had flooding issues, the generators were on a floor about 35' higher than the turbine pit. So two ropes were used to transmit the power from a 168 rpm turbine shaft with a 10' sheave to the 360 rpm generator shaft with a 4' 5.5" sheave. Two "1,250 foot long, one and one-half inch diameter 'Furmis' sisal ropes, imported from Brazil, were used to transmit power....Each rope was wound alternately over the upper sheave wheel and under the lower one; after its thirteenth loop, each rope was returned to its first groove via a 52 inch diameter tension carriage sheave." Each generator produced 500kw at a maximum of 2,500 volts. [HAER-data, p70-71] The turbines one one shaft could generate "850hp while discharging 32,460 cubic feet of water per minute (541 cfs)." [HAER-data, p69] Later, they determined that one rope could safely handle 900hp, thus there is only one rope connected in the photo. The belt on the right side of the photo drives an excitation DC generator
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| HAER WVA,2-SHEP.V,1--51 51. View of Generator No. 2 and upper sheave wheel. |
This shows that the equipment is normally shielded. I like the use of steel grates rather than sheet metal because that makes it easier to notice problems.
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| HAER WVA,2-SHEP.V,1--37 37. Credit JTL. Combard Type 'O' governor and generator Unit 1. |
We can see watermarks on the back wall depicting the various water levels of the Potomac River. But in all cases, the turbines are normally covered with water. We can also see a rod connects each wicket gate to something in the center. And a pinion gear on the little shaft along the top turns the "something," which then pushes and pulls the rods. A governor turns the little shaft.
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| HAER WVA,2-SHEP.V,1--27 27. Credit JTL. Turbine pit 1, Leffel turbines and wicket gates. |
"Once in the turbine pit, the water descended through a linked pair of Leffel Type 22 'Sansom,' (Leffel's trade name for a Francis) 40 inch diameter, dual runner, center discharge, horizontal shaft turbines and exited through a tapered steel draft tube. Each of the four dual runner turbines was equipped with a draft tube and, after falling 17 feet and 4 inches, the water flowed beneath the building." [HAER-data, p69]
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| Digitally zoomed from the above HAER WVA,2-SHEP.V,1- (sheet 5 of 6) |
This shows how the Frances turbines are mounted in pairs so that the flow of water through each of them is opposite of the other. This balances the lateral forces on the shaft. This is important because thrust bearings were yet to be developed in 1906.
A trend I've noticed in industrial history is that when a technology is first developed, several manufactures build it. For example, there were still eight tractor companies at the middle of the 20th Century. There were so many car manufacturers in the early 20th Century that I would not be able to count them. I've learned that generators join this phenomena. In addition to GE/Edison and Westinghouse, there was at least Warren Electric Manufacturing Co. of Sandusky, OH [HAER-data, p44,71] and Electric Machinery Co. of Minneapolis, Minnesota [p71].
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