Popular Science Monthly/Volume 24/February 1884/Under-Ground Wires > 자유게시판

본문 바로가기
사이트 내 전체검색

자유게시판

Popular Science Monthly/Volume 24/February 1884/Under-Ground Wires

페이지 정보

profile_image
작성자 Letha
댓글 0건 조회 2회 작성일 26-05-19 09:09

본문

image.php?image=b17maartent1220.jpg&dl=1

The ultimate worth of the stability in coal saving will depend upon the proportion of time by which the ability station operates to its full capability. This is basically due to the higher familiarity with the direct-current motor, to its better capacity and fewer price. This is probably due in large measure to the long standing figure of 600 volts for trolley service; this figure, nonetheless, is fastened by the character of the direct present motor and never by any consideration of possible hazard from shock. The value of alternating currents was not appreciated, however, as the rules of transformation and their value for transmission weren't understood. While certain traits of the alternating present system cut back this theoretical value fairly materially, the acquire in this respect is nonetheless huge, and the space between feeding points increases to between thirty and fifty miles, relying on the density of the site visitors. The amount of present taken by a train on this system could go to very large values and this necessitates giant trolley and feeding conductors when the site visitors increases in volume. Theoretically, the reduction in the dimensions of conductors obligatory to hold the present is inversely proportional to the square of the voltage.



This has lead to the development of alternating present methods, by which the power is generated, transmitted and delivered to the automotive at voltages as high as 15,000, with consequent discount in values of the mandatory present. As offsetting these marked advantages it is critical to consider the electrical losses in the transmission system and in the motor equipments. The only-part motor has the same traits and operates precisely because the direct present motor and will actually be operated by direct present-a reality which constitutes certainly one of its best benefits. This system is as yet solely four years previous, but there are at present over 1,000 miles of railways in the United States working underneath it and in this aggregate there are at least five railroads formerly operated by steam. Considering further the several pioneer installations of electric service, we find that they differ materially of their characteristics and there are a number of so-referred to as programs at current accessible. The standardization of electric railway apparatus is one in all the greatest requirements of the current state of affairs.



what-is-electric-cable-300x233.jpeg Further, the apparatus in the sub-stations in these techniques comprises stationary transformers solely which require no attendance. With increasing size of line the price of sub-stations and feeders in the direct current system turns into prohibitive. Although both the English and the German systems are successfully working traces of telegraph, they are far much less environment friendly than pole lines of the identical length. By coupling up the traces backwards and forwards between London and Manchester, Bright was enabled to acquire a steady size of over two thousand miles of underground lines. Moreover, it has been found that, for delicate and fast-working apparatus, corresponding to computerized telegraphs, polarized relays, and, above all, the telephone, long underground lines are far less environment friendly than pole strains. There are several thousand miles of wire in the sewers of Paris, and the price of the gutta-percha-covered cables is about $140 per mile of wire, or about 5 times the cost of a pole line to do the identical work. Figures have been published displaying that the Manhattan Railway below steam operation secured about 1.5 ton miles to a pound of coal; underneath electric operation this figure has increased to 3.85. These and different careful estimates point out that in the final electrification of via railway strains a saving of 50 per cent, in coal consumption may be effected.



The operating expenses of a mean steam railroad could also be roughly divided as follows: Maintenance of means 21 per cent., maintenance of tools 19 per cent., conducting transportation fifty six per cent., normal expenses four per cent. The common steam consumption of a great locomotive engine is about 30 pounds of steam per horse energy hour developed; turbo-generators are actually assured for a consumption of only 15 pounds of steam per electrical horse energy on the switchboard. In the case of the brand new York Central installation, the common distance between such stations is four miles. Between 1846 and 1852 many miles of somewhat related cables have been laid in France, however, excepting those laid in the sewers of Paris, they universally failed. Hardly was the section completed, nevertheless, when water found its means into the joints, destroying the insulation, and the conductors failed. The same amount of coal in a locomotive boiler will evaporate solely about two thirds as much water as in a stationary boiler.

댓글목록

등록된 댓글이 없습니다.

회원로그인

회원가입

사이트 정보

회사명 : 회사명 / 대표 : 대표자명
주소 : OO도 OO시 OO구 OO동 123-45
사업자 등록번호 : 123-45-67890
전화 : 02-123-4567 팩스 : 02-123-4568
통신판매업신고번호 : 제 OO구 - 123호
개인정보관리책임자 : 정보책임자명

접속자집계

오늘
3,177
어제
3,158
최대
13,572
전체
1,137,312
Copyright © 소유하신 도메인. All rights reserved.