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Part of the Russian–American Telegraph line bearing the single wire of an earth-return circuit, c. 1866. Earth-return telegraph is the system whereby the return path for the electric current of a telegraph circuit is provided by connection to the earth through an earth electrode. Using earth return saves a great deal of money on installation ...
An earthing system (UK and IEC) or grounding system (US) connects specific parts of an electric power system with the ground, typically the equipment's conductive surface, for safety and functional purposes. [1] The choice of earthing system can affect the safety and electromagnetic compatibility of the installation.
Long-distance electromagnetic telegraph systems from 1820 onwards [a] used two or more wires to carry the signal and return currents. It was discovered by German scientist C.A. von Steinheil in 1836–1837, that the ground could be used as the return path to complete the circuit, making the return wire unnecessary. [2]
The Hispano fired a 130 grams (4.586 oz) 20 mm diameter projectile from a 110 mm (4.331 in) long casing, the whole round weighing 257 g (9.065 oz). [19] Lengths of the projectiles varied with type but were set to variable depth in the casing to produce a total full round length of 184 mm (7.244 in) regardless of projectile type. [ 20 ]
The Wheatstone slip was a paper tape that contained holes in a pattern to control the mark and space signals on the telegraph line. The paper tape was from 0.46 to 0.48 inches in width, (but the standard width is from 0.472 to 0.475 inches) and a standard thickness of 0.004 to 0.0045 inches. [3]
The HS.820 is a 20 mm caliber autocannon developed by Hispano-Suiza primarily for aircraft use, but more widely used in a series of ground-based anti-aircraft guns. After Oerlikon purchased Hispano's armaments division in 1970, the HS.820 became the Oerlikon KAD, supplanting Oerlikon's own KAA and KAB weapons in the process. [1]
20 mm caliber is a specific size of popular autocannon ammunition. The dividing line between smaller-caliber weapons, commonly called " guns ", from larger-caliber " cannons " (e.g. machine gun vs. autocannon ), is conventionally taken to be the 20 mm round, the smallest caliber of autocannon.
The telegrapher's equations (or just telegraph equations) are a set of two coupled, linear equations that predict the voltage and current distributions on a linear electrical transmission line. The equations are important because they allow transmission lines to be analyzed using circuit theory . [ 1 ]