AC Power Plugs and Sockets: British and Related Types > 자유게시판

Theoretically, such protection could have been designated either within the socket or within the plug. Generally the plug is the movable connector attached to an electrically operated device's mains cable, and the socket is fixed on equipment or a building structure and connected to an energised electrical circuit. It embossed dots and dashes on a moving paper tape by a stylus which was operated by an electromagnet. Joseph Henry improved it in 1828 by placing several windings of insulated wire around the bar, creating a much more powerful electromagnet which could operate a telegraph through the high resistance of long telegraph wires. The indicator's pointer was moved by a polarised electromagnet whose armature was coupled to it through an escapement. When at the starting station the operator pressed a key, the corresponding pointer was deflected at the receiving station. The communicator's pointer was geared to the magneto mechanism. In the base of the communicator was a magneto actuated by a handle on the front. Schilling's telegraph was tested on a 5-kilometre-long (3.1 mi) experimental underground and underwater cable, laid around the building of the main Admiralty in Saint Petersburg and was approved for a telegraph between the imperial palace at Peterhof and the naval base at Kronstadt.

Underground lines are limited by their thermal capacity, which permits less overload or re-rating lines. The lines were connected at both ends to revolving dials marked with the letters of the alphabet and electrical impulses sent along the wire were used to transmit messages. Each half cycle of the current would advance the pointers at both ends by one position. A transmission would begin with the pointers on the dials at both ends set to the start position. The terminal characteristics of the transmission line are the voltage and current at the sending (S) and receiving (R) ends. E incoming line feeds a 3 phase supply and three single phase supplies, to a street distribution system (so that an industry therein connected can obtain 400v 3phase supply, whilst three houses can each obtain a single one phase supply and a fourth house obtains two single (different) phases - what kwh "poaer" is measured on either of it's two kwh meters, if a load is directly connected (NOT ACROSS EITHER PHASE AND N but) across two of the line phases, with out a n or e connection. There was also serious concern that an electrical telegraph could be quickly put out of action by enemy saboteurs, something that was much more difficult to do with optical telegraphs which had no exposed hardware between stations.

The two stations of Schilling's telegraph were connected by eight wires; six were connected with the galvanometers, one served for the return current and one for a signal bell. Pavel Schilling subsequently improved its apparatus by reducing the number of connecting wires from eight to two. Schilling was also one of the first to put into practice the idea of the binary system of signal transmission. The first telegram in the United States was sent by Morse on 11 January 1838, across two miles (3 km) of wire at Speedwell Ironworks near Morristown, New Jersey, although it was only later, in 1844, that he sent the message "WHAT HATH GOD WROUGHT" over the 44 miles (71 km) from the Capitol in Washington to the old Mt. Clare Depot in Baltimore. The Morse system uses a single wire between offices. In 1830 William Ritchie improved on Ampère's design by placing the magnetic needles inside a coil of wire connected to each pair of conductors.

In 1833, Carl Friedrich Gauss, together with the physics professor Wilhelm Weber in Göttingen, installed a 1,200-metre-long (3,900 ft) wire above the town's roofs. The page of Gauss's laboratory notebook containing both his code and the first message transmitted, as well as a replica of the telegraph made in the 1850s under the instructions of Weber are kept in the faculty of physics at the University of Göttingen, in Germany. At first, Gauss and Weber used the telegraph to coordinate time, but soon they developed other signals and finally, their own alphabet. In 1837, Davy invented the much more practical metallic make-and-break relay which became the relay of choice in telegraph systems and a key component for periodically renewing weak signals. The needles made symbols similar to the Chappe optical system symbols, making it more familiar to the telegraph operators. At the family home on Hammersmith Mall, he set up a complete subterranean system in a 175-yard (160 m) long trench as well as an eight-mile (13 km) long overhead telegraph. As a result, what are electric cables he was able to make the distant needle move in the direction set by the commutator on the other end of the line.