Other awards included the U. On his return to the United States, Dr. The fortunes ofwar prevented completion ofthe project, and in such plant and pertinent documentsas survived were taken to the U. The converter at the sending end is called a reetifier, and that at the receiving end kimbaark inverter.

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Barr The converter at the sending end is called a reetifier, and that at the receiving end an inverter. Either converter, however, can function as rectifier or inverter, permitting power to be transmitted in either direction. It aided further development ofvalves by permitting them to be tested under service conditions.

M uch of the time when power is delivered to Gotland, there are no generators in operation there, the only synchronous maehine being a condenser. The operation of the line was discontinued in in the belief that nothing more would be learned by continuing it. Power fiow is normally from the mainland to Gotland but kimbakr sometimes in the opposite direetion. Then switches 3 would be opened, isolating the faulted line. If a permanent fault occurred on the lower conductor, the converters connected to it would be controlled so as to bring the voltage and current on it to zero.

At present these are not capable of handling the highest voltages and powers required for HV dc transmission. Direct Current Transmission — Kimbark Lamm inhas considerably increased the peak inverse voltage diret the valves can withstand.

There are also several grading electrodes placed between the control grid and the anode for obtaining a teansmission uniform potential gradient than would otherwise existo The grading electrodes are kept at the desired potentials by connecting them to taps on an externaI resistance-capacitance potential divider the ends of which are connected to the anode and control grid.

The ac line, of course, also has this reversibility. The ac input at Mechanicville was at a frequency of 40 Hz, and the output at Schenectady was at 60 Hz. Next the converter voltages would be raised to equality with those of the respective adjacent converters, after which switches I currenh be closed. Their ratings have increased, however, with surprising rapidity, and it seems certain that such valves will soon kimnark mercury-arc valves in HV dc use.

Power is adjusted automatically to maintain rated frequency 50 Hz in Gotland. If the transformers are operated as an integral part of the link, only 10w-voItage circuit breakers are required. The current ratings are to A per anode. The neutral points junctions between converters are grounded at one or both ends. Each terminal has two converters of equal rated voltages in series on the dc side. The tine itself usually has two conductors, aIthough some Iines have only one, the return path being in the earth or seawater or both.

This being so, two parallel three-phase circuits are required for reliable transmission see Fig. The converter at each end of the line had kjmbark hot-cathode glass-envelope thyratrons in 6 series pairs. This system of grading elec trodes, invented by U. Large inductances ealled de. A fuIl-scale km mi overhead line between a hydroelectric plant at Volgograd, formerly called Stalingrad, and the Donets Basin was energized. One pole of a four conductor line is shown in Figure Id, with two converters per terminal.

Practical ground electrodes were developed, and various kinds of valves and converter control were tested. Direet-current links are classified as shown in Figure 2. The line initially operated at constant current, the conversions from con stant alternating voltage to constant current and vice versa being made by an LC bridge circuit called the monocyclic square. The United States was inactive in the field of dc transmission, however, for nearly 20 years.

Norrnally they operate at equal current; then there is no ground current. Livro — Whitebook Livro — Whitebook. Therefore three-pole switching is always used to clear permanent faults, although such a fauIt may involve only one conductor.

The Une loss would be four times its normal value, somewhat diminishing the delivered power. B1S The line carried 5. Related Posts


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