Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F38/00—Adaptations of transformers or inductances for specific applications or functions
  • H01F38/20—Instruments transformers
  • H01F38/22—Instruments transformers for single phase ac
  • H01F38/28—Current transformers
  • H01F38/30—Constructions
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
  • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
  • G01R31/001—Measuring interference from external sources to, or emission from, the device under test, e.g. EMC, EMI, EMP or ESD testing
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
  • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
  • G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
  • G01R31/58—Testing of lines, cables or conductors
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F27/00—Details of transformers or inductances, in general
  • H01F27/28—Coils; Windings; Conductive connections
  • H01F27/2823—Wires
  • H01F2027/2833—Wires using coaxial cable as wire
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F38/00—Adaptations of transformers or inductances for specific applications or functions
  • H01F38/20—Instruments transformers
  • H01F38/22—Instruments transformers for single phase ac
  • H01F38/28—Current transformers
  • H01F38/30—Constructions
  • H01F2038/305—Constructions with toroidal magnetic core

Definitions

• the invention relates to a device for injecting an electromagnetic signal into an electrical conductor, in particular for testing its insulation and protection characteristics with regard to electromagnetic disturbances. .
• Prior art Prior art.
• annular pliers which can be opened in two parts is used, which comprises a conductive wire wound on a ferrite core and connected to an appropriate signal generator, and which is placed around the cable to be tested.
• the subject of the invention is a device for injecting a signal onto an electrical conductor, which makes it possible to avoid these drawbacks.
• the device according to the invention which comprises an annular clamp in two parts intended to be placed around the conductive cable, and means for connection to a signal generator, is characterized in that the clamp comprises an internal tubular cylindrical conductor of low thickness, surrounded by an intermediate cylinder of material with ferromagnetic properties, and a very thick external tubular cylindrical conductor, the external and internal conductors being, at a first end, connected to the means of connection to the signal generator and, to their second end, connected to each other.
• the device according to the invention has a low load impedance, and a good efficiency, greater than 50% and which can reach 80 to 85%.
• the choice of section and length of the intermediate cylinder with ferromagnetic properties, which is for example in ferrite, makes it possible to determine the low cut-off frequency of the device as a function of the envisaged application.
• the bandwidth of a device according to the invention is between a few kilohertz and a hundred megahertz approximately.
• the clamp also comprises cylinders of dielectric material placed between the three aforementioned cylinders, as well as inside the internal cylindrical conductor and outside the external cylindrical conductor.
• cylindrical conductors of the clamp comprise, at their first end, very thick annular flanges by which they are connected to the means of connection to the signal generator.
• the means for connecting to the signal generator comprise at least one, and preferably two cables with two coaxial conductors, the internal and external conductors of which are respectively connected to the internal and external cylindrical conductors of the pliers.
• the device comprises conductive cylinders of small thickness, removable, making it possible to adapt the clamp to the diameter of the cable to be tested.
• FIG. 1 is a schematic half view in axial section of the device according to the invention.
• FIG. 2 is a schematic perspective view showing this partially open device. . Best way to realize the invention.
• the device shown schematically in Figures 1 and 2 is essentially in the form of an annular cylindrical clamp 10 in two parts 12 and 14 substantially identical, connected together by hinges of the hinged type, not shown. These two semi-cylindrical parts 12, 14 are also associated with locking means in the closed position around an electroconductive cable to be tested.
• Each part 12, 14 of the clamp comprises, from the inside to the outside, a half-cylinder 16 of dielectric material with low inducing power, a tubular semi-cylindrical conductor 18, of small thickness, made for example of copper, an intermediate half-cylinder 20 of material with ferromagnetic properties, such as ferrite, or any other material with high magnetic permeability, a cylinder 22 of dielectric material of the same type as that of cylinder 18, and an external tubular semi-cylindrical conductor 24 relatively thick.
• This external conductor 24 comprises, at its ends, annular flanges 26 oriented radially inwards.
• One of these flanges 26 comprises studs or connecting terminals 28, while the other annular flange 26 is connected to the corresponding end of the internal cylindrical conductor 18.
• the internal conductor 18 comprises or is connected to an annular rim 30 oriented towards the outside and carrying pads or connecting terminals 32, cor corresponding to the terminals 28 of the rim 26 of the external conductor 24.
• terminals 28 and 30 are, for example, silver and are used for connection, as shown in FIG. 2, of coaxial cables 34 whose external conductors 36 are going to be connected by terminals 28 to the external conductor 24 of the clamp 10 and whose internal conductors 38 will be connected by terminals 32 to the internal conductor 18 of the clamp 10.
• the annular flanges 26 and 30 of the conductors 24 and 18 are insulated from each other by a thickness 40 of dielectric material, which can also form insulation between the ferrite cylinder 20 and the internal conductor 18.
• An external plastic cylinder 42 covers and protects the external conductor 24 and the ends of the clamp.
• the ends of the clamp can be protected by half-discs 44 of plastic material, which are screwed or fixed by any suitable means to the ends of the cylinder 42.
• the internal 18 and external 24 conductors of the clamp are made of copper, aluminum, or any other suitable electroconductive material.
• the contact between the annular rim 26 of the external conductor 24 and the end of the internal conductor 16 is made by welding when the internal conductor 18 is not removable, or else by pressing with the interposition of a compressible conductor, for example a thin braid of copper, bronze, aluminum, or silver-plated copper wires.
• This device is used as follows:
• the coaxial cables 34 connected as indicated on the terminals 28 and 32 of the conductors 24 and 18 of the clamp, are connected to an appropriate signal generator, and the clamp is placed around a conductive cable to be tested, its two parts 12 , 14 being applied one on the other and locked in this position by any suitable means. It is essential that there is good contact between the edges of the two half-cylinders 20 of ferrite, so that the magnetic circuit is closed. To improve this contact, the edges of the conductive cylinders 18 and 24 can be dug a little to place a flexible and compressible conductor therein, such as a braid of conductive wires. It is then ensured, on closing the clamp, to obtain both a good connection of the edges of the ferrite half cylinders 20, and a good connection between the facing edges of the conductive half cylinders 18 and 24.
• the device according to the invention has a relatively low load impedance thanks to the arrangement of the coaxial cables 34 in parallel, which makes it possible to divide their common impedance by two, and at the low impedance of the conductive edges 26 and 30 and of the conductor external 24. It follows that the major part of the load impedance is constituted by the internal conductor 18, at the ends of which is applied almost all of the voltage difference between the external 36 and internal 38 conductors of the coaxial cables 34.
• the yield of the device according to the invention is greater than 50% and can reach 80 to 85%.
• the main characteristics of the device according to the invention are indicated below, by way of non-limiting example:

Landscapes

• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Electromagnetism (AREA)
• Shielding Devices Or Components To Electric Or Magnetic Fields (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=9362267

Family Applications (1)

Country Status (5)

Families Citing this family (11)

Family Cites Families (17)

• 1988
  • 1988-01-13 FR FR8800328A patent/FR2625855B1/fr not_active Expired - Lifetime
• 1989
  • 1989-01-10 EP EP89901467A patent/EP0355145A1/de not_active Withdrawn
  • 1989-01-10 WO PCT/FR1989/000003 patent/WO1989006805A1/fr not_active Application Discontinuation
  • 1989-01-10 US US07/415,287 patent/US5122773A/en not_active Expired - Fee Related
  • 1989-01-13 CA CA000588179A patent/CA1301268C/fr not_active Expired - Lifetime

Non-Patent Citations (1)

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