>>>2024-05-07 Electrical Characteristics of Telephone Lines (PDF) > 자유게시판

Power cables are used for bulk transmission of alternating and direct current power, especially using high-voltage cable. This telegraph was using a code able to transmit 20 letters, the other ones having to be omitted. What the railroads and the telegraph did here a century ago, what are electric cables the jets and communication satellites are doing now to all the world. It is our hope that these means of communication will serve increasingly as a carrier of the message of peace for which we both work and pray. When you complain, and the NID test shows the problem is on the telco side, they will likely just resplice your home telephone service onto a different pair back to the exchange. A couple of years ago in Philadelphia, workers for PECO Energy found that some underground utility cable still in service dated to 1899. In July 1999, the failure of outdated cable was blamed for power outages in Manhattan affecting 200,000 people. Before deregulation, companies like Con Edison would make investments in infrastructure that were deemed necessary, to maintain a level of service and reliability that met industry-wide standards, assured that state regulators would allow them to recover the costs, and maintain their financial health.

On top of this disinvestment policy, local distribution systems, like the transmission system, are being stretched beyond their design limits. And that is your local loop. It's called a loop because the two wires, connected at one end by the switch and at the other end by your phone, allow current to flow all the way around. There it often passes through an area called the cable vault, usually an underground space in or adjacent to the basement where cables enter the building, seeping water is drained, and pairs come out of the armored cable jacket. Additionally, the metal jacket itself is utilized as a ground. One of the purposes of armored cable's metal jacket is to eliminate the need for conduit, as the wire has its protective layer. Instead of being protected by NM cable sheathing, these wires are protected by tubular metal or plastic conduit. On this journey, the crew also retrieved the lost end of the first cable and reconnected it to its original end. Over the next several hours, five more feeder lines were lost.

Between 1990 and the year 2000, utility employment in power generation dropped from 350,000 to 280,000, as utilities looked for ways to slash costs, to be "competitive." Over the same decade, employment in transmission and distribution went from 196,000 to 156,000, in a system that is growing more complex by the day. The 2003 blackout did spur some increase in investment industry-wide, from $3.5 billion per year to $6 billion in 2006. But profit-minded companies are only willing to invest funds where there is a profit to be made, namely to carry their "economy transfers," regardless of how that destabilizes the grid system overall. Industry-wide, there is agreement that weaknesses due to the age of the underground distribution cable have been exacerbated by the way the system is run in today's deregulated world. Historically, instruments were considered part of the telephone system proper and were property of your telco. The difference doesn't really matter that much on the telephone end, but can be confusing if you are looking at documents that use different conventions. Under the no-holds-barred market of deregulation, this "elsewhere" has moved further and further away from the large cities, with their large power requirements, to areas of the country where power can be produced more cheaply, and new plants can be built with the minimum amount of local political opposition and legal interference.

Today, thanks to deregulation, a company can earn more profits by not building anything, and instead charging more for what they already produce, by creating shortages. Today, the average age of a power lineman is 50 years. Among the group of passengers no one listened more attentively to Dr. Jackson's recital than a New York artist, named Samuel Finley Breece Morse, who was returning from a three years' residence in Europe, whither he had gone for improve­ment in his art. Either one provides space for the many pairs in a cable to be spliced together, some to another cable but some to a drop line that runs to your house. Some of Con Edison's underground infrastructure goes back almost as far as Thomas Edison's first central generating station and underground cable, on Pearl Street in lower Manhattan, in 1882. It was a length of 59-year-old cable whose failure was a factor in the July blackout.