Prof. Charles Scott and the "Trolley-Feeder" system

pattbaa
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Joined: October 29th, 2003, 9:46 pm

August 10th, 2018, 11:10 am #1

Charles Sott achieved  fame  when he engineered the "Scott" transformer connection. His knowledge of transformers much assited the NHRR when  the 1907 Trolley-to-Rail system was causing  severe disturbances in telephone circuits ,and would be deficient for  the extension of the electrification system to New Haven. These problems were solved with the ingenous "Trolley-Feeder" system which was effected with minimum  installation  cost and  minimal "conversion" problems. The "key" was a unique auto ( single winding) transformer  connection which conducted a "Feeder" Current and a "Trolley" Current. Four "Feeders" were implaced along the ROW, one for each of the four Trolleys, which reduced  the line impedance by 1/2 . The Trolley-to-Feeder voltage  was 22,000 volts , reducing th line current by 1/2. The conversion was a model of planning and execution and accomplished  in only a few hours.This was another NHRR "first".
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Jim Vaitkunas
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Joined: August 9th, 2009, 11:41 am

August 11th, 2018, 1:18 pm #2

Fascinating.  I read the words but have no clue what you are saying.  I guess I'm not electrically inclined even tho I'm a volunteer at a Minnesota streetcar museum.
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rsullivan
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Joined: December 14th, 2016, 3:36 pm

August 12th, 2018, 3:41 am #3

I found this explanation of the trolley-feeder system described above on page 706 of Electric Railway Journal, vol. XLIII, no. 13, that was provided by Mr. Albert Brecken. I’m going to cut it down some by paraphrasing portions and quoting the explanation part.
               Mr. W.S. Murray was a speaker at a conference and described the “new 22,000-volt balanced distribution system…installed…to eliminate electromagnetic effects on adjacent telephone and telegraph lines.” Apparently this communication problem was the “last straw that had been held up against a.c. traction” and this removed that straw. Mr. Murray was at Cos Cob on a telephone with “Harlem River yards at New York, 25 miles away…could not hear distinctly.” The 22,000-volt system was substituted and Mr. Murray “could distinguish no difference in the clearness of the telephone transmission during a period of four hours” while loads were changing up to “23,000 kva.” With the new system there is “11,000 volts between each trolley wire and ground, a total difference of potential between the two sides of the circuit of 22,000 volts. The rails act as if they formed the neutral conductor of a three-wire system. Auto-transformers are used to transfer the return current from the rail to an aerial circuit connected with the power house.”
               It shows a diagram indicating +11,000 volt trolley input, direction of current flow in both directions between the trolley and rails with the electric locomotive being a one direction source of power to the rail, and one direction current flow from the tracks to the -11,000 volt feeder. The +11,000 volt trolley and the -11,000 volt feeder are connected to the auto-transformer which flows the current only from the -11,000 feeder to the +11,000 volt trolley.
               I wonder if this was what the DCC companies did to eliminate “noise” that interfered with signals on the model railroad a.c. power to tracks system running our model locomotives?
               Hope this helps clarify the original post, and definitely ties the development to the New Haven Railroad.
Richard #3967
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