US2051708A - Electric commutator and interrupter according to the spark-neglecting principle - Google Patents

Description

Aug. 18, 1936. J. F. G. P. HARTMANN 2,051,708

ELECTRIC COMMUTATOR AND INTERRUPTER ACCORDING TO THE SPARK NEGLECTING PRINCIPLE Filed Dec. 17, 19:54 3 Sheets-Sheet 1 g- 1936. J. F. G. P. HARTMANN ELECTRIC COMMUTATOR AND INTERRUPTER ACCORDING To THE SPARK NEGLECTING PRINCIPLE Filed Dec. 17, 19:54

3 Sheets-Sheet 2 J F. e. P Hwfwsm Aug. 18, 1936. J. F. s. P. HARTMANN 2,051,708

, ELECTRIC COMMUTATOR AND INTERRUPTER ACCORDING TO THE SPARK NEGLECTING PRINCIPLE Filed Dec. 17, 1954 3 Sheets-Sheet 3 i aten ted Aug. 18, 1936 UNITED STATES ELECTRIC COMNIUTATOR AND INTERRUPT- ER ACCORDING TO THE SPARK-NEG- LECTING PRINCIPLE Julius Frederik Georg Poul Hartmann, Copenhagen, Denmark Application December 17, 1934, Serial No. 757,931 In Denmark December 22, 1933 9 Claims.

The invention relates to electric commutators and interrupters according to the spark-neglecting or spark independent principle with one or more conductive liquid jets, especially to a hydrodynamic system for use in connection with such apparatus. Generally speaking the apparatus in question is that in which the spark produced during the operation takes place between points substantially on the conductive liquid so that the stationary parts of the apparatus are not cor roded. The jet-wave commutator, the plate-jet commutator, the spiral-jet commutator and the jet-chain commutator may be mentioned as examples of commutators of this kind. Generally the conductive liquid will be mercury. Concerning the apparatus mentioned reference may be had to the specifications of the U. S. Patents Nos. 1,306,335, 1,365,491, 1,578,287, 1,567,367, 1,664,031, 1,708,061, 1,851,704, 1,919,633 and 1,930,933, together with Jul. I-Iartmann: Mercury-jet commutation and its technical possibilities, Engineering Nov. 20, and Dec. 11, 1931.

By the practical use of mercury jet commutators according to the spark-neglecting principle, especially the above named jet-wave commutator, irregularities in the function of the commutator have been disclosed by working for some length of time, which has been found to be due to the depositing of a grey powder in the interior of the apparatus, especially at the edge of the jet opening. A further examination has shown that this powder substantially consists of small balls of pure mercury covered with fine particles of mercuric oxide, preventing the uniting of the mercury balls. Notwithstanding the presence in the electrode chamber of an inactive gas, usually hydrogen, which is constantly supplied from a store and kept under a weak overpressure oxygen must therefore be present in the chamber. This oxygen unites with the mercury under the influence of the commutation spark thus forming the said mercuric oxide. Without the cooperation of the spark mercury, practically, is not oxidized in contact with the air.

Experiments have shown that the'appearance of oxygen in the electrode chamber, among other things, is due to the following causes:

The mercury moves in a circuit, being reconducted from the electrode chamber, that is by means of a pump to the reservoir from which the jet is supplied. As during the passage from the electrode chamber back to the reservoir the mercury contacts with atmospheric air there is the possibility that small amounts of the latter are conducted through the jet conduit to the electrode chamber. V

It-is'the purpose of the present invention to completely preclude this carrying along of atmospheric air. 7

Accordingly the invention generally consists in keeping the liquid circuit externally closed, and in everywhere keeping the free space of the circuit, that is, the part not filled out by liquid, filled by inactive gas. Practically, the gas will generally be the same as that present in the electrode chamber. 1

Other features of the invention will appear from the following description in connection with the drawings, in which- Figures l-3 show various embodiments of mercury jet-commutators, schematically, the electrode and the magnet system together with other parts irrelevant to the invention having been omitted. V r

The apparatus shown in Figure 1 consists of an electrode chamber l made ofsteel-plate Welded together. At the top the chamberis closed by aheavy insulating plate ll fastened in a's teelframe 12, having a perpendicular flange l3 below projecting into a groove l4 containing mercury, said groove being provided at the upper edge of the chamber. Laterally the chamber I0 is provided with a liquid lock l5, also containing mercury and serving as a safety valve, and a well I6 is provided at the bottom of the chamber, in which well the mercury leaving the chamber is collected. This well is connected by a conduit 11 with the suction chamber l8 of a centrifugalpump l9 having a perpendicularshaft- 20. The shaft is surrounded by a casing 2| tightly connected to the pump house and forming at its lower part a narrow passage around. said shaft so as to make a very narrow gap. During the working, the mercury level is as shown in the well l6 and the'casing 2| so that a volume having a little free surface and not participating in the circulation produced by. the pump is separated from the main part of the mercury'in the casing 2|. Substantially the same volume of mercury will therefore constantly be'present in the casing 2|. This volume forms a lock between the external air and the liquid flowing in the circuit.

Thepressure chamber 22 of the pump is connected by a conduit 23 with a tubular piece 24, in

the uppermost part of which a partition 25 with an aperture is provided so that the mercury'as shown passes the main part of the tubular piece as a continuous jet which below hits a bottom piece 26 inserted in the tubular piece so that the jet is spread through apertures 21 in the sidewall of the tubular piece. The falling mercury is received in a container 28 surrounding the lowermost end of the tubular piece 24, the bottom of said container being perforated so that the mercury now, as a shower of drops, falls further down to a reservoir 29, from which a jet conduit 30 leads to the chamber In, the conduit 30 being carried airtight through the plate ll. At its top the reservoir 29 supports a tubular piece 3|, surrounding the space, through which the mercury drops are passing, and also the container 28, said piece being closed at its upper end by an insulating plate 32 through which the tubular piece 24 is carried.

Below the partition 25 an inlet conduit 33 for inactive gas, as for instance hydrogen, is connected to the tubular piece 24, said gas passing through the piece 24 around the mercury jet and through the apertures 21 to the container 28 where the space above the'mercury is totally filled by the gas. From the bottom piece 26 a short tubular piece 34 open below leads through the perforated bottom of the container 28, said tubular piece having openings 35, in its upper part through which the gas is conveyed to the chamber in which the mercury drops fall down.

From the reservoir 29 is branched an overflow passage 36', which is carried air-tight through the plate ll. At the overflow passage 36 is provided an extension 3'! containing a device corresponding to that constituted by the parts 24, 26, 21, 28-, 34 and 35, and serving to produce a rain of mercury in the lowermost part of the extension 31, said mercury rain having also for its purpose to provide an electric interruption in the circulating current of mercury. At the end of the conduit 36 projecting into the chamber l0 said conduit is provided with an extension 38 having a perforated bottom through which the mercury flows to the chamber Ill, while the inactive gas which is carried along with the mercury escapes through openings 39 at the top of the extension 38. Both parts of the conduit 36 have such a diameter that the normal amount of overflowing mercury is not able to wholly fill out the conduit. The mercury therefor will carry with it bubbles of the gas so that the conduit acts as a pump for the gas.

A conduit 40 carried through the plate H is connected to the conduit 33 over a three-way cock 4| normally having the position I so as to conduct the amount of gas passing through the conduit 36 through the conduits 40 and 33 back to the tubular piece 24. In this manner an auxiliary circuit is provided for the inactive gas from the electrode chamber lllover the reservoir 29 back to the electrode chambers l0 outside of the jet-conduit 30. The circulation of the gas in this circuit is effected by the above-mentioned adaption of the overflow passage 36. When first the circuit is filled with inactive'gas, the cock 4! has the position II. The gas then is supplied through a conduit 43, and the air in the circuit escapes through a nozzle 42. The gas normally is supplied from a gasometer connected to the conduit 43. By normal operation this gasometer serves to maintain a constant over-pressure in the electrode chamber and the liquid circuit.

For commutating high tensions the inactive gas in the closed circuit may be kept under a considerable over-pressure. As, normally, the circuit including the chamber and pump will not everywhere be able to resist such-a pressure, it may be surrounded by a container in which substantially the same pressure is maintained as in the circuit. Alternatively, the electrode chamber ID with appurtenances (the parts 24, 30, 3|, 33, 36 and 3'!) and the pump with driving motor respectively may be surrounded each by their own container with substantially the same pressure as in the circuit. However, this leads to constructions by which the active parts of the apparatus become difficult of access. More preferable embodiments are shown in Figures 2 and 3.

In Figure 2 the driving motor 5| of the pump 53 is surrounded by a dome 52, in which substantially the same pressure as in the circuit is maintained.

Thus it becomes possible, as in Figure 1, to retain a free surface of mercury in the casing surrounding the pump shaft. The electrode chamber Hi is itself shaped as a cylindrical pressure container with curved bottom and cover. The cover is made of steel-plate and provided with tubular insulators 53 where it is necessary. The remaining parts of the circuit will, without particular measures, be able to resist a considerable pressure.

Figure 3 as compared with Figure 2 shows that the insulating plate ll used in Figure 1 is retained. In order to relieve the plate ll of strains owing to the pressure in the electrode chamber ill, the plate is outwardly surrounded by a dome 54, in which the same pressure as in the closed circuit is maintained. In view of the mounting,

flange-couplings 55 are inserted in the conduits 30, 36 and 40-, which flange-couplings are accessible through a door 56 in the dome 54.

The invention is not restricted to the embodimentsshown, but the latter may be altered in various respects without departing from the scope of the invention. Thus it is not important whether as a neutral gas a single gas or more gases in mixture are used, and different gases may be used at different places in the circuit.

Having thus fully described my invention I claim as new and desire to secure by Letters Patent:

1. For use in connection with electric commutators and interrupters according to the sparkneglecting principle a hydrodynamic system comprising a circuit fora conductive liquid, preferably mercury, including an electrode chamber and a reservoir for the conductive liquid, said circuit being externally closed and the free space thereof being filled with an inactive gas, an auxiliary circuit for the saidgas being provided from the electrode chamber over the said reservoir and back to the electrode chamber.

2. For use in connection with electric commutators and interrupters according to the sparkneglecting principle a hydrodynamic system comprising anexternally closed circuit for a conductive liquid, preferably mercury, including an electrode chamber and a reservoir for the conductive liquid, the free space of said circuit being filled with an inactivegas, said reservoir being provided with an overflow passage for surplus liquid, an auxiliary circuit for the inactive gas being provided including the said electrode chamber, the reservoir and the overflow passage, said passage debouching in the free space of the electrode chamber and being adapted to circulate the said gas in the auxiliary circuit.

3. For use inconnection with electric commutators and interrupters according to the sparkneglecting principle a hydrodynamic system comprising an externally closed circuit for a conductive liquid, preferably mercury, including a pump, said pump being provided with a substantially vertical shaft projecting outside the system, said shaft being surrounded by a casing tightly connected to the pump housing and forming at its lower part a narrow passage around said shaft in order to separate out a liquid volume which does not participate in the circulation in the circuit and serving to seal said circuit against the external air.

4. For use in connection with electric commutators and interrupters according to the sparkneglecting principle a hydrodynamic system comprising an externally closed circuit for a conductive liquid, preferably mercury, the free space in the said circuit being filled with an inactive gas at a material over-pressure, said circuit including a pump, a motor being provided for driving the pump, said motor being surrounded by a dome connected to the pump housing, and in which is maintained substantially the same pressure as in the circuit.

5. For use in connection with electric commutators and interrupters according to the spark-neglecting principle a hydrodynamic system comprising an externally closed circuit for a conductive liquid, preferably mercury, including an electrode chamber composed of a main part built as a pressure container and an insulating cover, the free space in the said circuit being filled with an inactive gas at a material overpressure, said cover at its outer side being surrounded by a dome in which is maintained substantially the same pressure as in the said circuit.

6. For use in connection with electric commutators and interrupters according to the spark-neglecting principle a hydrodynamic system comprising a circuit for a conductive liquid, preferably mercury, confined by solid walls and including an electrode chamber and a pump outside said chamber, said liquid being separated from the external atmosphere over a substantial part of the circuit by the walls of the circuit only, an inactive gas being present in the electrode chamber, all parts of the circuit being closed and sealed from the exterior, and all spaces not occupied by the liquid being filled with inactive gas.

7. For use in connection with electric commutators and interrupters according to the spark-neglecting principle a hydrodynamic system comprising an externally closed circuit for a conductive liquid, preferably mercury, including an electrode chamber and a pump outside said chamber, all spaces of the said circuit not occupied by the liquid being filled with an inactive gas subjected to a material pressure above atmospheric.

8. For use in connection with electric commutators and interrupters according to the spark-neglecting principle a hydrodynamic system comprising an externally closed circuit for a conductive liquid, preferably mercury, confined by solid walls, including an electrode chamber and a pump outside said chamber, all spaces of said circuit not occupied by the liquid being filled with an inactive gas subjected to a material overpressure, said circuit including the walls thereof being at least partly surrounded by a separate container in which is maintained substantially the same pressure as in the circuit.

9. For use in connection with electric commutators and interrupters according to the spark-neglecting principle a hydrodynamic system comprising an externally closed circuit for a conductive liquid, preferably mercury, confined by solid walls including an electrode chamber and a pump outside said chamber, all free spaces of the said circuit not occupied by the liquid being filled with an inactive gas at a material over-pressure, said electrode chamber being built as a pressure container.

JULIUS FREDERIK GEORG POUL HARTMANN.

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