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Publication numberUS3806841 A
Publication typeGrant
Publication dateApr 23, 1974
Filing dateJan 29, 1973
Priority dateJan 29, 1973
Also published asCA1003915A1
Publication numberUS 3806841 A, US 3806841A, US-A-3806841, US3806841 A, US3806841A
InventorsBrunner R
Original AssigneeAllis Chalmers
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Frequency-sensitive resistor and electrical transmission system embodying such resistor
US 3806841 A
Abstract
A frequency-sensitive resistor whose resistance increases with increase in frequency, and which is particularly adapted for insertion in or in combination with an electrical transmission line for the purpose of damping or attenuating undesirable high frequency electrical transients. In one embodiment of the invention, the frequency-sensitive device comprises a center conductor of copper or other good conductive material on which are mounted in axially spaced relation to each other a plurality of fins such as disks or the like. The fins are formed of or at least coated with a material having a higher resistance than the material of the center conductor. At low power frequencies such as 60 hertz, the resistor device has negligible resistance since currents at low power frequencies pass substantially entirely along the center low resistance conductor and do not enter the higher resistance material of the fins. Upon the occurrence of high frequency electrical transients, due to the skin effect phenomenon the high frequency transients flow in a relatively thin skin across the higher resistance surfaces of the fin members, to thereby cause substantial damping or attenuation of the high frequency transients. In a modified construction in accordance with the invention, a shell-like member formed of or coated with a higher resistance material, and having a corrugated or undulating outer peripheral surface, is mounted in place of the plurality of fins on the low resistance center conductor, but functions in a manner similar to the fins to substantially damp or attenuate high frequency transients. In both embodiments, a relatively long and circuitous high resistance path is provided for the high frequency transients which promotes the damping or attenuation of the high frequency transients.
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Description  (OCR text may contain errors)

United States Patent [191 Brunner F REQUENCY-SENSITIVE RESISTOR AND ELECTRICAL TRANSMISSION SYSTEM EMBODYING SUCH RESISTOR Richard G.-Brunner, Foxboro, Mass.

[73] Assignee: Allis-Chalmers Corporation,

Milwaukee, Wis.

[22] Filed-: Jan. 29, 1973 [21] Appl. No.: 327,676

[75] Inventor:

[52] us. or. 333/81 R, 333/79 Primary Examiner-Archie R. Borchelt Assistant Examiner-Marvin Nussbaum Attorney, Agent, or FirmRobert C. Sullivan [57 [ABSTRACT A frequency-sensitive resistor whose resistance increases with increase in frequency, and which is particularly adapted for insertion in or in combination with an electrical transmission line for the purpose of [451 Apr. 23, 1974 damping or attenuating undesirable high frequency electrical transients. In one embodiment of the invention, the frequency-sensitive device comprises a center conductor of copper or other good conductive material on which are mounted in axially spaced relation to each other a plurality of fins such as disks or the like. Thefins are formed of or at least coated with a material having a higher resistance than the material of the center conductor. At low power frequencies such as 60 hertz, the resistor device has negligible resistance since currents at low power frequencies pass substantially entirely along the center low resistance conductor and do not enter the higher resistance material of the fins. Upon the occurrence of high frequency electrical transients, due to the skin effect phenomenon the high frequency transients flow in a relatively thin skin across the higher resistance surfaces of the tin members, to therebycause substantial damping or attenuation of the high frequency transients. In a modified' construction in accordance with the invention, a shell-like member formed of or coated with a higher resistance material, and having a corrugated or undulating outer peripheral surface, is mounted in place of the plurality of fins on the low resistance center conductor, but functions in a manner similar to the fins to substantially damp or attenuate high frequency transients. In both embodiments, a relatively longand circuitous high resistance path is provided for the high frequency transients which promotes the damping or attenuation of the high frequency transients.

13 Claims, 5 Drawing Figures PATEN'I'EDAPRZ3 1974 GEN RATOR STEP DOWN TRANSFORMER "LOAD STATION WAVE TRAP RMEP WAVE TRAP cuzcun' BREAKER" -C\PC UIT BREAKER IOO MILE TRANSMISSlON LINE GENERATOR STEP UP TRANSFO WAVE TRAP GENERATING STATION 1 FREQUENCY-SENSITIVE RESISTOR AND ELECTRICAL TRANSMISSION SYSTEM EMBODYING SUCH RESISTOR BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a resistor having a resistance value which varies as a function of the applied frequency, and to an electrical transmission line or system embodying such a resistor. Although not necessarily restricted thereto, the frequency-sensitive resistor of the invention has particular value for use in damping or attenuating undesirable high frequency transient currents and voltages in high voltage electrical transmission systems.

2. Description of Prior Art When a circuit breaker is closed to energize or reclose a power line, voltage surges of relatively high magnitude and high frequency may be produced. This problem is particularly acute during the switching operation for energizing a capacitor bank when prestriking causes traveling waves which are amplified at a cable line junction and reflect at a transformer terminal and cause end-of-the-line overvolta ges of, for example, several times normal crest voltage. High magnitude, high frequency voltage surges also occur on a transmission line when lightning strikes equipment connected to the line.

The high frequency transients of the type which might occur on a high voltage transmission line may have frequencies, for example, in the range 1 kilohertz to l megahertz (i.e., 1,000 cycles/sec. to 1,000,000 cycles/sec).

One welLknown method of reducing the magnitude of switching surges is to preinsert a resistance of suitable value into the circuit during the closing operation just prior to the moment at which the main contacts engage. Other methods have involved the use of parallel surge-modifying capacitances in parallel with the transformer terminals; and a third prior art method of attenuating the undesirable high frequency transients in a transmission line or the like has been the use of series inductances in the line. The prior art methods just briefly discussed are undesirable since they are costly, involve high losses, and the resistor insertion method mentioned requires the use of separate switching means for the insertion of the resistor.

It is also known to utilize conductor arrangements for attenuating undesirable high frequency transients which operate upon the principle that high frequency currents tend to flow substantially only in the radially outer peripheral portion of the conductor due to the well-known skin effectprinciple. Prior art teachings of high frequency transient attenuation which show utilization of the skin effect principle include US. Pat. Nos. 3,480,382 issued to Herman R. Person; 3,531,264 issued to Herman R. Person; 3,541,473 issued to Heinz M. Schlicke et al.; and 3,543,105 issued to Robert I. Van .Nice.

A literature reference relating to a utilization of the skin effect principle for attenuation of high frequency harmonics is provided in an article entitled High Frequency AC Harmonics on a HVDC Transmission Line Might Be Attenuated by Conductor Design by John R. Abbott, published in the periodical Transmission and Distribution, August, 1969, pp. 58-60 inclusive.

STATEMENT OF THE INVENTION Accordingly, it is an object of the present invention to provide a frequency-sensitive resistor having a resistance value which varies as a function of the applied frequency.

It is a further object of the invention to provide a frequency-sensitive resistor which has particular utility for use in damping or attenuating high frequency currents or voltages in an electrical transmission system.

It is an object of the present invention to provide an electrical resistor which is a good conductor for low frequencies such as cycle phenomena but which presents a substantial resistance for high frequency phenomena such as switching transients and traveling waves.

It is another object of the invention to provide for insertion in or in combination with an electrical power transmission line or system or the like a wave trap in the form of a frequency-sensitive resistor which attenuates or damps high frequency electrical phenomena such as switching transients and traveling waves but which presents a good conductive path for low frequency phenomena such as 60 hertz (60 cycle/sec.) phenomena.

It is another object of the invention to provide a frequency-sensitive resistor which provides a short and good conductive path for low frequency phenomena such as 60 cycle power, but which provides a relatively long and circuitous high resistance path for undesirable high frequency transient phenomena whereby to damp the high frequency transient phenomena.

In achievement of these objectives there is provided a frequency-sensitive resistor whose resistance increases with increase in frequency, and which is particularly adapted for insertion in or in combination with an electrical transmission line or system for the purpose of damping or attenuating undesirable high frequency electrical transients. in one embodiment of the invention, the frequency-sensitive device comprises a center conductor of copper or other good conductive material on which are mounted in axially spaced relation to each other a plurality of fins such as disks or the like. The fins are formed of or at least coated with a material having a higher resistance than the resistance of the material of the center conductor. At low power frequencies such as 60 hertz, the resistor device has negligible resistance since currents at low power frequencies pass substantially entirely along the center low resistance conductor and do not enter the higher resistance material of the disks. Upon the occurrenceof high'frequency electrical transients, the high frequency transients flow in a relatively thin skin across the higher resistance surfaces of the fin members, to thereby cause substantial damping or attenuation of the high frequency transients. In a modified construction in accordance with the invention, a shell-like member formed of or coated with a higher resistance material, and having a corrugated or undulating outer peripheral surface, is mounted in place of the plurality of fins on the center conductor, but functions in a manner similar to the fins to substantially damp or attenuate high frequency transients. In both embodiments, a relatively long and circuitous high resistance path is provided for the high frequency transients which promotes the damping or attenuation of the high frequency transients.

BRIEF DESCRIPTION OF THE DRAWING Further objects and advantages of the invention will become apparent from the following description taken in conjunction with the accompanying drawing in which:

FIG. 1 is a perspective view of one embodiment of the invention which includes a plurality of fins or disks formed of or coated with higher resistivity material and mounted in axially spaced relation to each other along a low resistivity conductor member of copper or the like;

FIG. 2 is a view in longitudinal section of the embodiment of FIG. 1 showing the path of flow of the high frequency transients;

FIG. 3 is a view in axial cross section of a modified embodiment of the invention in which a hollow shell- Iike member having a corrugated peripheral surface formed of or coated with higher resistivity material is mounted on an axially extending conductor of low resistivity, such as copper or the like;

FIG. 4 is a schematic illustration of typical installation of frequency-sensitive resistors (or wave traps) in series with an electrical transmission line; and

FIG. 5 is a schematic diagram showing the utilization of the frequency-sensitive resistor of the invention for attenuating high frequency phenomona in connection with capacitor bank switching.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIG. 1, there is shown a frequency sensitive resistor member generally indicated at which may be connected, for example, in series with a high voltage transmission line. The resistor 10 includes an axially extending conductor member 12 made of copper, aluminum, or other good conductive material. A plurality of fin members such as the disk members indicated at 14, I6, 18, and 22 are mounted on the conductor 12 in axially spaced relation to each other and with the radially inner periphery of the fin members in conductive contact with conductor 12. The fin members 14, 16, 18, 20 and 22 are made of, or altematively coated on the external surface thereof with, preferably a high resistivity material such as iron, bronze, or other suitable material having a higher resistivity than the center conductor 12. If the fins are coated with a resistance material, the coating should be in conductive contact with the conductor 12 or otherwise conductively connected to conductorl2. In the embodiment shown in FIG. l,-the disks are each approximately three-eighths inch thick in an axial direction. The axial thickness of the disks is made such that the high frequency transient currents will not pass directly through the disks in an axial direction, but rather will flow in a skin on the outer surface of the respective disks, as will be explained hereinafter. In a typical embodiment, the fins or disks might have a diameter of ap' proximately 10 inches, for example. The fin members 14-22, inclusive, could also be of other geometrical shapes, such as square or rectangular, for example. The fins or disks 14-22, inclusive, must be axially spaced from each other along conductor 12 sufficiently to withstand the transient voltage gradient, whereby to prevent flash-over between contiguous disks.

At normal power frequencies, such as 60 cycles, the resistance of the resistor device 10 is negligible since the power frequency currents flow substantially entirely along the copper conductor 12 and do not flow along the surface of the higher resistance disk members 1422, inclusive. However, as best seen in the high frequency current flow diagram of FIG. 2, upon the occurrence of high frequency transients, such high frequency transients when first entering the resistor. device 10 flow along conductor 12 until they reach the disk 14. Due to the well'known skin effect principle, the high frequency transients then travel from conductor 12 in a skin-like layer radially across the face 14A of disk 14 to the outer periphery of disk 14, then axially across the outer peripheral edge 14B of the disk 14, hence radially inwardly along the face 14C of disk 14 to conductor 12, then along conductor 12 to the radially inner edge of disk 16, and thence radially outwardly and inwardly along the surfaces of the successive disks 16, 18, 20 and 22 in the same manner as described in connection with the disk 14. It can be seen that for a given over-all axial length of resistor device 10, the plurality of fins or disks provide a long and tortuous or circuitous high resistance path for the undesirable high frequency transients which has a pronounced damping effect on the high frequency transients.

The skin effect principle causes the high frequency transients to flow substantially only in a relatively thin skin which extends perpendicularly inwardly from the respective surfaces such as 14A, 14B and 14C of disk or fin 14. The depth of the skin is measured in a direction perpendicular to the respective surfaces 14A, 14B and 14C.

The skin depth at a given frequency will vary with different materials. For a comprehensive discussion of skin effect, reference is made to the publication Reference Data For Radio Engineers, Fourth Edition, I 6, second printing 1957, published by International Telephone & Telegraph Corporation, (See Chapter 5, pages 128-132, inclusive).

There is shown in FIG. 3 a modified frequencysensitive device generally indicatedat 50 which operates on the same general principles as the device of FIG. 1, and is also suitable for insertion in a high voltage electrical transmission line or system for the purpose of damping or attenuating high frequency electrical transients.

Referring now to FIG. 3, there is shown a center conductor 52 of copper or other suitable good conductive material. A hollow shell-like member generally indicated at 54 is secured at the opposite ends thereof to the conductor 52 by welds 56 or by other suitable attaching means. At the opposite ends thereof, the device 54 has end walls 58 which extend radially from center conductor 52. The outer peripheral surface of the device 54 between the opposite end walls thereof is provided with corrugations or undulations as indicated at 60. The shell-like device 54 is made of, or alternatively, coated on the exterior surface thereof, with a material such as bronze or iron having a higher resistivity than the material of center conductor 52. The device 50 typically might have an outer diameter at the crest of the corrugations, of about 10 inches.

If the device 50 is connected into a high voltage electrical transmission line, currents at power frequencies, such as 60 cycles, will pass substantially entirely along the low resistance center copper conductor 52 and will not enter the material of the shell-like member 54. However, upon the occurrence of high frequency transient currents, such transient currents will flow in a skin on the end walls 58 and in a skin along the corrugated or undulated outer peripheral surface 60 of the shell 54. The higher resistance material of which the shell 54, or of a coating thereon (if the shell is merely coated with high resistance material) is made, together with the elongated tortuous or circuitous path for the high frequency currents provided by the structure of shelllike member 54 including the corrugations or undulations 60, will cause substantial damping or attenuation of the high frequency transients.

The disks 14-22, inclusive, of the embodiment of FIG. 1, and the shell 54 of the embodiment of FIG. 2 may also be made of, or at least coated with, any one of various metals or alloys having a higher resistance than copper (assuming the center conductor 12 or 52 is made of copper), such as those listed in Table 3, page 6-04, in Electrical Engineers Handbook Electric Power, Fourth Edition, Wiley Engineering Handbook Series, New York; John Wiley & Sons, Inc., Third Printing, April, 1956. Suitable metals or alloys .for use in making or coating the disks 1422, inclusive, or in making or coating the shell 54 in addition to the bronze and iron already mentioned, include the following ma terials from the foregoing table 3: aluminum; No. 30 alloy; brass; beryllium copper (heat treated); phosphor bronze, 5 percent (grade A); nickel; No. 60 alloy; platinum; No. 90 alloy; lead; Everdur No. 1010; No. 180 alloy; 18 percent nickel silver; Monel metal; Manganin (copper, manganese, nickel); Cupron (copper, nickel); Constantan (copper, nickel); Advance (copper, nickel); Stainless steel, No. 302; Nichrome V (nickel, chromium); Tophet A (nickel, chromium); Nichrome (nickel, chromium, iron); Tophet C (nickel, chromium, iron).

In addition to the foregoing list of materials, the disks 14-22, inclusive, or the shell-like member 54 may be formed of or at least coated with materials having high permeability, high resistance characteristics such as those listed in the aforementioned US. Pat. No. 3,541,473 to Heinz M. Schlicke et al. Such materials may include various nickel-iron alloys known as the Permalloys," wherein the basic nickel-iron alloy may be varied to include chromium, copper or molybdenum, as desired.

The foregoing list of materials is merely intended to be illustrative of materials which may be used and other suitable materials which may be used instead.

If the fins 1422, inclusive, of the embodiment of FIG. 1 or the shell-like member 54 of the embodiment of FIG. 3, are merely coated with the high resistance material, the underlying material supporting the coating may be of any material suitable to serve as a mechanical support'for the coating and need not have electrical conductive properties. If the disks are coated with the high resistance material, the coating should be applied to the entire external surface of each fin, i.e. surfaces, A, B and C of FIG. 2. If the shell-like member of FIG. 3 has a high resistance coating applied thereto, such coating need be applied only to the external surface of the shell. In either the embodiment of FIG. 1 or FIG. 3, if a high resistance coating is used, the thickness of the coating should at least be equal to the skin depth corresponding to the low end of the frequency range of the electrical transients which it is desired to damp or attenuate for the particular resistance material being used. That is, for example, if it is desired to damp electrical transients in the frequency range 1 kilohertz to l mergahertz, and the high resistance coating is of iron, I

filled with material. However, the space shown and described as being hollow in member 54 basically has no bearing on the functioning of the device 50 since the high frequency transients flow substantially only in a relatively thin skin contiguous the outer surface of member 54.

Refer now to FIG. 4 which schematically shows a typical installation of frequency-sensitive resistors or wave traps in accordance with the invention in series with an electrical transmission line. There is shown a generating station generally indicated'at 100, including an electrical generator 102 having its output connected to the transmission line 104 through a step-up transformer 106, a first frequency-sensitive resistor 108 or wave trap and a circuit breaker 110. At the generating station end, preferably another frequency-sensitive resistor 11-1 is interposed between circuit breaker 110 and transmission line 104. Note that the first frequency-sensitive resistor 108 is interposed betweenthe stepup trans former 106 and the circuit breaker 110 and the second frequency-sensitive resistor 111 is interposed between circuit breaker 110 and transmission line 104.

The opposite end of the transmission line 104, which may be I00 miles long, for example, is connected toa load 114 at a load station generally indicated at 112 through a circuit breaker 116, a frequency-sensitive resistor 118, and a step-down transformer 120. Note that the frequency-sensitive resistor 118is interposed between the circuit breaker 116 and the step-down transformer 120. The frequency-sensitive resistor or wave traps 108, 111 and 118 diagramatically shown in FIG. 3 may be of any of the types hereinbefore described and each may respectively include a plurality of wave traps, as dictated by the requirementsof the installation.

The transmission line 104 diagramatically shown in FIG. 4 would normally be a three-phase transmission line and the frequency-sensitive resistors or wave traps shown in FIG. 4 would normally be connected in each of the three phases of the transmission line. In a transmission line such as that shown in FIG. 4, the normal voltage transmitted may be of the order of magnitude of 700 kilovolts phase-to-ground, for example.

energizing a capacitor bank or stage when one or more stages have already been previously energized. Thus, referring to FIG: 5, there is shown a transmission line 200 connected at one end to a generator 202' and at its opposite end to a load 204. Two capacitor banks or stages generally indicated at 206 and 208, respectively, are connected to transmission line 200 in parallel relation to each other and in close proximity to each other for supplying reactive kilovolt amperes (KVA) to the power system, as is well known in the art. Capacitor bank 206 is connected to transmission line 200 by a switch 210 in series with a frequency-sensitive resistor or resistors (or wave trap) indicated at 212 and capacitor bank 208 is connected to transmission line 200 by a switch 214 in series with a frequency-sensitive resistor or resistors (or wave trap) 216. The switches 210 and 214 may be vacuum switches which, as is well known, have advantages when used for capacitor switching. The capacitor banks 206 and 208 each have the same capacity and the switching involved in connection with such capacitor banks is commonly referred to in the art as back-to-back switching;

Assume that capacitor bank 206 is already connected to the power system due to the fact that switch 210 is closed and that it is then desired to connect capacitor bank 208 to the system to supply additional reactive KVA.

The switching operation just described has presented a problem in the prior art where it is desired to switch into the system a capacitor bank such as 208 where one or more capacitor banks such as capacitor bank 206 are already energized, since unusually high values of inrush current at high frequencies to capacitor bank 208 can result. In fact, with one or more capacitor banks or stages previously energized, the transient peak inrush current to the bank being switched into the system may exceed 200 times the normal peak steadystate capacitor current. The maximum peak inrush current that flows under such circumstances is contributed by the discharge of the energized capacitor stage or stages into the newly switched stage. In the prior art, the only significant impedance available to restrict the flow of this transient current is the resistance and inductive reactance inherent in the conductors connecting the parallel connected capacitor banks such as banks 206 and 208.

The frequency-sensitive resistors 212 and 216 will limit or damp the high frequency transients which would normally flow due to the closure of switch 214 to energize capacitor bank 208 in the assumed exam ple. Resistors 212 and 216 would also, of course, limit or damp high frequency transients which would flow if the opposite condition to that just described prevailed, namely that capacitor bank 208 was already energized and switch21 0 was 'beingclosed to energize capacitor bank 206.

In connection with the description of the'problem relating to switching parallel capacitor banks, reference is made to an article entitled Switching Parallel Capacitor Banks" by R. W. Peterson, which appeared in the Allis-Chalmers Electrical Review, Third Quarter, 1962.

While the embodiments of the invention have been described and shown as a separate assembly which is connected into an electrical transmission line, it is obvious that the center conductor 12 (FIG. 1) or 52 (FIG. 3) could be the transmission line conductor itself, with the frequency-sensitive resistor being completed by mounting the fins 14-22, inclusive,'(FIG. l) or the shell-like member 54 (FIG. 3) onto line conductor.

the transmission From the foregoing detailed description of the invention, it has been shown how the objects of the invention have been obtained in a preferred manner. However, modifications and equivalents of the disclosed concepts such as readily occur to those skilled in the art are intended to be included within the scope of this invention.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

l. A frequency-sensitive resistor whose resistance increases as a function of the frequency of electrical phenomena applied thereto, comprising a conductor member of good electrical conductivity adapted to be connected in an electrical circuit, and means providing an alternative circuit path for high frequency electrical phenomena comprising conductor means of lower electrical conductivity than said conductor member, said conductor means being mounted on and in electrically conductive relation with said conductor member and extending radially outwardly from the outer periphery of said conductor member, said means providing an alternative circuit path being arranged to define a tortuous or circuitous path for high frequency electrical phenomena, whereby in combination with the lower electrical conductivity of said conductor means to substantially damp said high frequency electrical phenomena, said means providing an alternative circuit path comprising a plurality of fin-like members mounted in spaced relation to each other along the longitudinal axis of said conductor member and in electrically conductive relation with said conductor member, said conductor member being adapted to be connected into an electrical circuit contiguous opposite ends of said longitudinal axis, said fin-like members comprising said conductor means of lower electrical conductivity, whereby high frequency transients flow in a skin on said conductor means and also along said conductor member between adjacent fin-like members.

2. A frequency-sensitive resistor as defined in claim 1 in which said fin-like members are formed of an electrically conductive material of lower electrical conductivity than said conductor member.

3. A frequency-sensitive resistor as defined in claim 1 in which said fin-like members are coated on the external surface thereof with an electrically conductive material of lower electrical conductivity than said conductor member.

4. A frequency-sensitive resistor whose resistance increases as a function of the frequency of electrical phenomena applied thereto, comprising a conductor member of good electrical conductivity adapted to be connected to an electrical circuit, and means providing an alternative circuit path for high frequency electrical phenomena comprising conductor means of lower electrical conductivity than said conductor means, said conductor means being mounted on and in electrically conductive relation with said conductor member and extending radially outwardly from the outer periphery of said conductor member, said means providing an alternative circuit path being arranged to define a tortuous or circuitous path for high frequency electrical phenomena, whereby in combination with the lower electrical conductivity of said conductor meansto substantially damp said high frequency electrical phenomena, said means providing an alternative circuit path comprising a shell-like member mounted on said conductor member, said shell-like member including end wall portions spaced apart from each other along the longitudinal axis of said conductor member and in electrically conductive relation with said conductor member, and a connecting wall portion lying radially outwardly of the periphery of said conductor member and connecting said end wall portions, said shell-like member comprising said conductor means of lower electrical conductivity than said conductor member whereby to define said alternative circuit path between the longitudinally opposite ends of said shell-like member, said shell-like member having the surface thereof corrugated or undulated whereby to increase the length of the path followed by said conductor means of lower conductivity.

5. A frequency-sensitive resistor as defined in claim 4 in which said shell-like member is formed of an electrically conductive material of lower electrical conductivity than said conductor member.

6. A frequency-sensitive resistor as defined in claim 4 in which said shell-like member is coated on the external surface thereof with an .electrically conductive material of lower electrical conductivity than said conductor member.

7. An electrical transmission system comprising a conductor member of good electrical conductivity, and means providing an alternative circuit path for high frequency electrical phenomena .comprising conductor means of lower electrical conductivity than said conductor member, said conductor means being mounted on and in electrically conductive relation with said conductor member and extending radially outwardly from the outer periphery of said conductor member, said means providing an alternative circuit path being arranged to define a tortuous or circuitous path for high frequency electrical phenomena, whereby in combination with the lower electrical conductivity of said conductor means to substantially damp said high frequency electrical phenomena, said means providing an alternative circuit path comprising at least one fin-like member mounted on and extending radially outwardly from the periphery of said conductor member, said fin-like member being-in electrically conductive relation at the inner periphery of said fin-like member with said conductor member, said fin-like member comprising said conductor means of lower electrical conductivity than said conductor member, said conductor means being in the form of a coating on the external surface of said finlike member, whereby high frequency electrical transients flow in said coating.

8. An electrical transmission system comprising a conductor member of good electrical conductivity, and means providing an alternative circuit path for high frequency electrical phenomena comprising conductor means of lower electrical conductivity than said conductor member, said conductor means being mounted on and in electrically conductive relation with said conductor member and extending radially outwardly from the outer periphery of said conductor member, said means-providing an alternative circuit path beingarranged to definea tortuous or circuitous path for'high frequency electrical phenomena, whereby in combination with the lower electrical conductivity of said conductor means to substantially damp with high frequency electrical phenomena, said means providing an alternative circuit path comprising a plurality of tin-like members mounted in spaced relation to each other along the longitudinal axis of said conductor member and in electrically conductive relation with said conductor member, said fin-like members comprising said conductor means of lower electrical conductivity, whereby high frequency transients flow in a skin on said conductor means and also along said conductor member between adjacent fin-like members.

9. An electrical transmission system as defined in claim 8 in which said fin-like members are formed of an electrically conductive material of lower electrical conductivity than said conductor member.

10. An electrical transmission system as defined in claim 8 in which said fin-like members are coated on the external surface thereof with an electrically conductive material of lower electrical conductivity thansaid conductor member.

11. An electrical transmission system comprising a conductor member of good electrical conductivity, and means providing an alternative circuit path for high frequency electrical phenomena comprising conductor means of lower electrical conductivity than said conductor member, said conductor means being mounted on and in electrically conductive relation with said conductor member and extending radially outwardly from the outer periphery of said conductor member, said means providing an alternative circuit path being arranged to define a tortuous or circuitous path for high frequency electrical phenomena, whereby in combination with the lower electrical conductivity of said conductor means to substantially damp said high frequency electrical phenomena, said means providing an alternative circuit path comprising a shell-like member mounted on said conductor member, said shell-like member including end wall portions spaced apart from each other along the longitudinal axis of said conductor member and in electrically conductive relation with said conductor member, and a connecting wall portion lying radially outwardly of the periphery of said conductor member and connecting said end wall portions, said shell-like member comprising said conductor means of lower electrical conductivity than said conductor member whereby to define said alternative circuit path between the longitudinally opposite ends of said shell-like member, said shell-like member having the surface thereof corrugated or undulated whereby to said conductor member.

,Po-ww UNITED sTATEs PATENT OFFICE CERTIFICATE OF CORRECTION Patch: No, 3,806,841 Dated 23, 1974 Invent r( RiChaI fd G. Brunner It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 10, line 2, "with" should read said Signed and sealed this 1st day of October 1974.

(SEAL) Attest: MCCOY M. GIBSON JR. I c. MARSHALL DANN Attesting Officer Commissioner of Patents

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Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US4156215 *Mar 21, 1977May 22, 1979RadiallCoaxial microwave attenuator having conical radial line absorbing members
US5338332 *Jun 15, 1992Aug 16, 1994Metricom, Inc.Current sensor using current transformer with sintered primary
US5661450 *Nov 21, 1995Aug 26, 1997Sun Microsystems, Inc.Low inductance termination resistor arrays
US5883565 *Oct 1, 1997Mar 16, 1999Harris CorporationFrequency dependent resistive element
US6407340Sep 1, 2000Jun 18, 2002Obducat AbElectric conductor with a surface structure in the form of flanges and etched grooves
US8596084 *Aug 17, 2010Dec 3, 2013General Electric CompanyIcemaker with reversible thermosiphon
US20120042680 *Aug 17, 2010Feb 23, 2012Herrera Carlos AIcemaker with reversible thermosiphon
EP2284997A1 *Jul 14, 2009Feb 16, 2011ABB Research Ltd.Low pass filter device
WO1999021244A1 *Oct 1, 1998Apr 29, 1999Harris CorpA frequency dependent resistive element
WO1999045752A1 *Mar 5, 1999Sep 10, 1999Etchtech Sweden AbElectric conductor with a surface structure in the form of flanges and etched grooves
Classifications
U.S. Classification333/81.00R
International ClassificationH03H7/24, H01P1/22
Cooperative ClassificationH01P1/22, H03H7/24
European ClassificationH03H7/24, H01P1/22