US3108243A

US3108243A - Liquid cooled resistor

Info

Publication number: US3108243A
Application number: US138686A
Authority: US
Inventors: Lomar Bertil; Myklebust Roger
Original assignee: ASEA AB
Current assignee: ABB Norden Holding AB
Priority date: 1961-09-18
Filing date: 1961-09-18
Publication date: 1963-10-22
Anticipated expiration: 1980-10-22

Description

United States Patent 3,108,243 LIQUID COOLED RESISTOR Berti] Lemar and Roger Myidebust, Ludvika, Sweden, assignors to Allmanna Svenska Elektriska Aktiebolaget, Vasteras, Sweden, a corporation of Sweden Filed Sept. 18, 1961, Ser. No. 138,686 7 Claims. (Cl. 338-54) The present invention relates to a means for power resistance comprising resistor units consisting of resistors placed inside tubes of electrically insulated material so that the said units are connected to a common electrical and mechanical connection point.

Within diiferent fields of elect-ro-technique, for example, high voltage direct current, with certain damping processes, great amounts of energy must be destroyed in damping resistances. If these damping resistances to all parts lie on a high potential, construction problems arise in building the resistor and cooling since it is desirable to have a pump aggregate and control equipment on the earth potential. It is already known to produce power resistances of the above mentioned type by placing the resistance in an oil-filled vessel so that the end points of the resistances must be connected to high voltage bushing insulators. It is also known to produce power resistances such as air-cooled resistances, but for higher powers these resistances are very bulky and expensive. Even a power resistance according to the first mentioned type is very expensive, partly because of the considerable oil quantity which is required to fill the vessel and partly because of the relatively expensive high voltage bushing insulators. Further, the considerable oil quantity required for such a device is unsatisfactory from the fire risk point of view.

The device according to the invention offers a cheap construction where insulating elements in the construction serve as both supporting construction par-ts and as cooling channel systems, and Where the volume of fluid required for cooling and insulating is reduced.

The invention is characterised in that said units at their common connection point are mounted on a tubeshaped pillar of insulating material provided to insulate the electrical connection point of the resistance units from the earth potential.

The invention will be described in the following with reference to the accompanying schematical drawing in which FIGURE 1 shows a partly cut view of a construction according to the invention and FIGURE 2 the same device seen from above.

The device shown in FIGURE 1 comprises resistance units 1 which are mechanically and electrically connected to a metallic expansion vessel 2, which also acts as control chamber for the cooling medium. The expansion vessel 2 is in its turn mounted on an insulating pillar 3 which is provided with an insulating tube 4 concentrically placed in the insulating pillar 3. The lower opening of the insulating tube 4 opens into a tube 9 which is in connection with a pump aggregate 6. The pump aggregate 6 is connected by means of a tube 7 on its pressure side, to a cooler 8, which by means of a tube is connected to the lower opening of the ringshaped channel which is formed between the insulating tubes 3 and 4. Each of the resistance units 1 consists of an outer insulating tube 14 and an inner insulating tube 13. The space between said insulating tubes is partly fill-ed by a resistance winding 19 which at one end is connected to the output 11 and at the other end is connected to the expansion vessel 2 and thus its connection point. The inner insulating tube 13, as the resistance winding 19, is kept in its position inside the outer tube 14 by means of an insulating draw bolt 12. Each resistance is 3,108,243 Patented Oct. 22, 1963 further provided with a flash-over ring 15 and with exhaust pipes 16 which connect the upper part of the ringshaped cooling channel of each resistance unit with the upper part of the expansion vessel. In the expansion vessel is also arranged a float 18 which, via an insulating rod 19, is provided, by means of a member not shown, to give a signal or effect a disconnecting of the resistor if the oil level in the expansion vessel becomes too low.

The resistance element 1 and expansion vessel 2 which have a high potential are insulated from the earth potential with the help of the tubesshaped insulator pillar 3. When power is developed in the resistances 10 these must be cooled, otherwise they would be rapidly destroyed. In the construction a fluid cooling medium is used, which by means of the pump 6 via the tube 7, cooler S and tube 9 is pumped out into the ring-shaped channel which is formed between the insulating tubes 3 and 4 and which terminates in a control chamber situated in the lower part of the expansion vessel 2. The outflow of the ringchannel is through the opening 20' in the control chamber connected to the inner insulating tube 13 in one of the resistance elements 1A. The cooling medium flows through the opening 20 and through the insulating tube 13, after which it is led into the ring-channel between the

tubes

14 and 13. During its passage through the ring-channel, the cooling fluid flows past the resistance 16 in the first resistance unit 1A so that the heat energy developed in the resistance is led off. The cooling medium is led further from the resistance unit 1A to the resistance unit 113 through a tube 21 which opens into the inner tube 13 in the resistance unit 18. The cooling medium passes through the resistance unit 113 in the same way as through 1A and is led further through the tube 22 to the resistance unit 1C, the outer ring-channel of which opens into the expansion vessel 2. The cooling medium circulates further from the expansion vessel 2 through the insulating tube 4 and conduit 5 via the pump 6 and tube 7 to the cooler 8 where the cooling medium is cooled. In order to prevent the formation of air pockets in the ring-channel between the

tubes

13 and 14 in the resistance units, exhaust pipes 16 are arranged between the upper part of the ring-channel between the tubes 13 and M and the upper part of the expansion vessel 2. In order to protect the expansion vessel and the conduits attached to this from flash-over across the resistances or between the common connection point and earth a metallic flash-over ring 15 is airanged at the junction between the resistance units and the expansion vessel 2. Since the air in the upper part of the expansion vessel should be as dry as possible, a container 17 containing a material which absorbs humidity is arranged in the communication between the expansion vessel and open air. To control the oil level in the expansion vessel 2 a float 18 and an insulating rod 19 joined to this are arranged to influence a control device so that a signal or disconnection of the resistance occurs when the oil level becomes too low.

The embodiments of the invention described herein have been found particularly advantageous for damping resistances subject to great and continual load. -It is, however, possible within the scope of the invention, to carry out other constructive solutions to the problem without altering the principle of the method of operation of the invention.

We claim:

1. Power resistance means comprising a plurality of units each including an outer tube of electrically insulating material and a resistance mounted in said tube, a tube-shaped pillar of insulating material, said outer tubes and said pillar having concentrically mounted inner tubes therein with their outer walls spaced from. the inner walls of the outer tubes and the pillar, said outer tubes each having its inner end supported by said pillar above the bottom thereof so as to. insulate them from earth potential, said inner ends being electrically connected, and means interconnecting the interiors of the inner tubes and the spaces between the outer walls of the inner tubes and the inner walls of the outer tubes and pillar to form a passage through said interiors and spaces in series, said resistances being positioned in said passage so as to be contacted by a cooling medium flowing therethrough.

2. In a power resistance means as claimed in claim 1, said interconnecting means producing flow inone direction with respect to the inner ends of the tubes in all of the inner tubes within the outer tubes and flow in the opposite direction in all of the spaces between the outer and the inner tubes.

3. In a power resistance means as claimed in claim 1,

said resistances being mounted in the spaces between the outer tubes and the inner tubes.

4. In an apparatus as claimed in claim 1, the outer free ends of the units being lower than the inner ends.

5. In an apparatus as claimed in claim 1, means forming an expansion chamber extending upwardly from the column above the inner ends of the units, said expansion vessel having internal Walls therein forming a part of said passage forming means.

6. In an apparatus as claimed in claim 5, exhaust pipes connecting the expansion chamber with the upper part of each of the spaces between the inner tubes and the outer tubes.

7. In an apparatus as claimed in claim 5, float means in said expansion chamber responsive to the level of liquid therein to sense the level of such liquid.

References Cited in the file of this patent UNITED STATES PATENTS 1,101,050 Baerl ocher June 23, 1914 1,320,890 Moifat Nov. 4, 1919 1,365,421 MacKay Ian. 11, 1921 2,735,057 Schaelchlin Feb. 14, 1956

Claims

1. POWER RESISTANCE MEANS COMPRISING A PLURALITY OF UNITS EACH INCLUDING AN OUTER TUBE OF ELECTRICALLY INSULATING MATERIAL AND A RESISTANCE MOUNTED IN SAID TUBE, A TUBE-SHAPED PILLAR OF INSULATING MATERIAL, SAID OUTER TUBES AND SAID PILLAR HAVING CONCENTRICALLY MOUNTED INNER TUBES THEREIN WITH THEIR OUTER WALLS SPACED FROM THE INNER WALLS OF THE OUTER TUBES AND THE PILLAR, SAID OUTER TUBES EACH HAVING ITS INNER END SUPPORTED BY SAID PILLAR ABOVE THE BOTTOM THEREOF SO AS TO INSULATE THEM FROM EARTH POTENTIAL, SAID INNER ENDS BEING ELECTRICALLY CONECTED, AND MEANS INTERCONNECTING THE INTERIORS OF THE INNER TUBES AND THE SPACES BETWEEN THE OUTER WALLS OF THE INNER TUBES AND THE INNER WALLS OF THE OUTER TUBES AND PILLAR TO FORM A PASSAGE THROUGH SAID INTERIORS AND SPACES IN SERIES, SAID RESISTANCES BEING POSITIONED IN SAID PASSAGE SO AS TO BE CONTACTED BY A COOLING MEDIUM FLOWING THERETHROUGH.