WO1995023326A1

WO1995023326A1 - Method and device for checking the integrity of the electrical insulating means of an object comprising conductors

Info

Publication number: WO1995023326A1
Application number: PCT/FR1995/000189
Authority: WO
Inventors: François PARADIS
Original assignee: Elmetherm
Priority date: 1994-02-25
Filing date: 1995-02-17
Publication date: 1995-08-31
Also published as: FR2716721A1; FR2716721B1

Abstract

A method comprising the steps of placing an object (12) in an ionisable gas (22) adjacent to at least one electrode (24), creating a voltage differential between conductors (14) and the electrode (24), and observing any flow of current that may occur between the conductors (14) and the electrode (24) as a result of a leak in the insulating means (18). The method is useful for checking the electrical imperviousness of the connecting splice insulating means in electrical cables, conducting wire insulation coverings, etc.

Description

Method and device for checking the integrity of electrical insulation means of an object corriportant of the conluctive means.

The present invention relates to a method and a device for controlling the integrity of means for electrically isolating an object comprising conductive means. It applies in particular to the control of the electrical tightness of insulating means such as sheaths or insulating coatings for electric cables or electrical connectors, or else such as sleeves for insulating connection splices. of electric cables.

In the automobile industry, the quality controls of the various components of the vehicles are more and more strict in order to improve the reliability of the vehicles. The quality controls are applied in particular to the bundles of electric cables and more particularly to the splices and to the connectors for connection of these cables.

The splices are generally electrically insulated by means of plastic sleeves placed around the bare junction ends of the cables. The sleeves are heated so that they shrink and tightly enclose the splices. Preferably, the sleeves are filled with an insulating polymerizable resin before they are heated.

It is known to control the electrical tightness of a splice by immersing it in a conductive bath and checking the good electrical insulation of the insulating means covering the splice. This control process destroys

The controlled splice and its realization is relatively long due to the fact that the bath takes a certain time to penetrate into the interstices of the defective insulating means of the splice. Furthermore, when the dimensions of these gaps are too small, the bath cannot penetrate it and leaks are not detected. Furthermore, the destruction of controlled splices is costly and does not allow systematic checks to be made of all the splices of the electrical harnesses of a vehicle.

It is also known to check the electrical tightness of a splice or connector by placing one end of the element to be checked in contact with a pressurized gas and by detecting the possible passage of pressurized gas to the other end of the element, corresponding to a leak in the element.

Such a control method does not make it possible to detect defective non-through holes. Indeed, in this case, the gas under pressure coming from one end of the element is blocked at the bottom of the hole without it being possible to detect the passage of this gas at the other end of the element. As a result, some defects in the inspected items may go undetected. The tightness of an insulator covering the conductive core of a cable can also be checked by dielectric breakdown. According to this method, a very high voltage difference is established between the conductive core of the cable and an electrode placed in the vicinity of this cable. The cable and the electrode are generally placed in air, which requires a very high voltage difference to cause breakdown between the conductive core and the electrode, in the event of an insulation fault.

Furthermore, the checked element is degraded during breakdown and this breakdown being instantaneous it is difficult to visualize the location of the fault.

The invention aims to remedy these drawbacks and to control the integrity of electrical insulation means of an object comprising conductive means, without destroying the object, preferably allowing locate the possible fault on the object, even in the case of a fault of very small dimensions.

To this end, the subject of the invention is a method for checking the integrity of means for electrically isolating an object comprising conductive means, characterized in that:

- The object is placed in an ionizable gas, near at least one electrode, the pressure of this gas being between 0.1 and 500 millibars absolute; - A voltage difference is established between the conductive means and the electrode; and

- We observe the possible passage of current between the conductive means and the electrode due to a leak in the insulating means. According to the characteristics of different embodiments of this process:

- the ionizable gas comprises a gas chosen from air, neon, helium, argon, krypton, xenon, carbon dioxide and nitrogen and the distance between the object and the electrode is between 2 mm and 35 mm; the object being filiform, the object is scrolled continuously in front of the electrode;

- We observe the appearance of an electro-luminescent discharge between the object and the electrode due to the passage of current between the conductive means and the electrode, in the event of a leak in the insulating means;

- The voltage between the conductive means and the electrode is between 500 and 5000 V;

- the object is placed between two electrodes; a voltage difference is established between the electrodes so as to ionize the gas and form a permanent plasma surrounding the object for the duration of the control; and an electrical quantity proportional to the intensity of the current flowing between the conducting means and the electrode, in case of failure of ^one sealing insulating means;

- the voltage between the two electrodes is between 100 and 2000 V; - the distance between the two electrodes is between 5 and 35 mm.

The invention also relates to a device for checking the integrity of electrical insulation means of an object comprising conductive means, characterized in that it comprises an enclosure containing an ionizable gas, the pressure of which is between 0.1 and 500 millibars absolute, at least one electrode housed in the enclosure, near which the object is intended to be placed inside the enclosure, means for establishing a voltage difference between the conducting means and the electrode, and means for observing the possible passage of current between the conducting means and the electrode, corresponding to a defect in the sealing of the insulating means. According to the characteristics of different embodiments of this device:

- the ionizable gas comprises a gas chosen from air, neon, helium, argon, krypton, xenon, carbon dioxide and nitrogen and the distance between the object and the electrode is between 2 mm and 35 mm;

- The electrode comprises a full conductive body, preferably aluminum, isolated from the ionizable gas except on one of its faces, in contact with the ionizable gas, at the right of which the object is intended to be placed; - the object being filiform, the electrode has a face to the right of which the object is intended to be placed, elongated along the length of the object;

- The electrode comprises a conductive hollow body, delimited by a grid or a solid wall, the object being intended to be placed inside the body; - The electrode has a generally tubular shape and has two separable parts at an axial junction plane so as to facilitate the introduction of the object to be checked inside the electrode; the means for establishing a voltage difference between the conductive means and the electrode include an additional connector intended to be connected to the connector to be checked so as to connect all the pins of this latter connector to the same potential;

- the object being filiform, the enclosure comprises orifices for passage of the ends of the object;

- The passage openings are provided with sealing means preferably comprising rubber rings surrounding the ends of the object;

- The passage openings are connected to a vacuum circuit, the device further comprising means for continuously scrolling the object in front of the electrode; the means for observing the current flow comprise means of visual access inside the enclosure making it possible to observe the appearance of an electroluminescent discharge between the object and the electrode due to the current flow between the conductive means and the electrode, in the event of a leak in the insulation means;

- the device comprises two electrodes housed inside the enclosure, between which the object is intended to be placed inside the enclosure, and a DC voltage generator connected to the terminals of the electrodes in order to ionize the gas between these electrodes and form a permanent plasma around the object for the duration of the control;

- the spacing between the two electrodes is between 5 and 35 mm; the means for observing the current flow comprise an electrical control circuit connecting the conducting means of the object and one of the electrodes with a potential different from that of the conducting means; - the electrical control circuit comprises an ammeter connected in series with an electrical dipole forming a resistor or a generator of direct voltage;

- The dipole is an electrical resistance, the circuit further comprising a voltmeter connected to the terminals of this dipole;

- The conductive means are connected to ground, and the means for observing the possible passage of current comprise a voltmeter connected between ground and an electrode; the device comprises means of visual access to the interior of the enclosure making it possible to observe a localized variation in the color of the plasma, in the event of a leak in the insulating means;

- The device further comprises at least one metal tip connected to the electrode, to the right of which is intended to be placed the part of the object which is most likely to have a leak.

Other characteristics and advantages of the invention will appear on reading the description which follows, given solely by way of example, for the understanding of which reference will be made to the appended drawings in which:

- Figure 1 is a schematic sectional plan view of a device according to a first embodiment of the invention;

- Figure 2 is a schematic sectional plan view of a device according to a second embodiment of the invention; - Figure 3 is a view is a schematic sectional plan view of a device according to a third embodiment of the invention;

- Figure 4 is a schematic sectional plan view of a device according to a fourth embodiment of the invention;

- Figure 5 is a schematic sectional plan view of a device according to a fifth embodiment of the invention; - Figure 6 is a sectional view, on an enlarged scale, along line 6-6 of Figure 5;

- Figure 7 is a schematic sectional plan view of a device according to a sixth embodiment of the invention. FIG. 1 shows a device according to a first embodiment of the invention, designated by the general reference 10, for checking the integrity of means of electrical insulation of an object comprising so many medium conductors. In the example illustrated, the object is an electric cable 12 comprising a conductive core 14 covered with a plastic insulating sheath 16.

The cable 12 comprises two sections connected together in a manner known per se by a splice covered by insulating means 18, of known type, comprising a plastic sleeve filled with an insulating resin.

The device 10 comprises an enclosure 20 intended to contain an ionizable gas 22.

An electrode 24, of generally cylindrical shape, is housed inside the enclosure 22.

The electrode 24 comprises a solid conductive body 25, preferably made of aluminum, of generally cylindrical shape, one face 26 of which is in contact with the ionizable gas 22. The other face 28 and the lateral surface 30 of the body 25 are coated with a conventional electrical insulator 32.

The device 10 makes it possible to control the electrical tightness of the insulating means 18 covering the splice of the cable 12.

To this end, the cable 12 is placed inside the enclosure 20, so that the insulating means 18 are arranged in line with the bare face 26 of the electro¬, near this face 26, of preferably at a distance between 2 and 35 mm from this face 26.

Preferably, the ends of the cable 12 extend to the outside of the enclosure 20, through orifices 34 formed in opposite walls of this enclosure. The passage openings 34 are provided with sealing means preferably comprising rubber rings 36 surrounding the ends of the cable 12.

To check the sealing of the insulating means 18, the terminals of a DC voltage generator 38 are connected on the one hand to the conductive core 14 and on the other hand to the electrode 24, so as to establish a voltage difference between these elements 14,24.

In the event of a leak in the insulating means 18, there occurs a stable light-emitting discharge 40 extending between the insulating means 18 and the electrode 24, due to the passage of current between this electrode and the conductive core 14. In Indeed, the ionizable gas penetrates into the interstices of the defective insulating means, even when these have very small dimensions, and comes into contact with the conductive core 14 covered, along the splice, by the defective insulating means 18 The gas in contact with the core 14 and the electrode 24 ionize when these elements 14, 24 are connected to the terminals of the voltage generator 38, this causing the appearance of the stable electroluminescent discharge resulting from the current flow between the core 14 and the electrode 24. The discharge can become fleeting if the leak is very small.

The discharge 40 occurs at the location of the leak, for example at the end of the sleeve 18, as illustrated in FIG. 1.

The enclosure 20 comprises means of visual access to the interior thereof, for example a transparent wall, allowing an operator to observe the appearance of the discharge 40 and therefore to detect a fault d sealing of the insulating means 18 and the location of this defect.

Preferably, the ionizable gas is chosen from air, neon, helium, argon, krypton and xenon, the pressure of this gas is between 0.1 and 500 millibars absolute and the terminal voltage of the generator 38 is between 500 and 5000 V.

Carbon dioxide or nitrogen can also be used as the ionizable gas, in order to avoid the effects of ionic nitriding of the electrodes. -

The device 10 and the tightness control method according to the invention make it possible to detect insulation faults consisting of both a blind hole and a through hole formed in the resin in which the splice is embedded, these faults causing the appearance of a stable electroluminescent discharge when a voltage difference is applied between the core 14 of the cable and the electrode 24. In the case of a through hole through and through the insulating means 18, the discharge occurs along the easiest path between cable 12 and electrode 24.

In Figure 1, there is shown a single cable 12 provided with a splice placed inside the enclosure 20. Of course, it is possible to check the sealing of the insulating means of the splices of several cables at the same time, by placing these cables substantially parallel to one another through the orifices 34, so that the splices are placed substantially in line with the bare face 26 of the electrode 24. It is also possible to control one or more splices connecting a number n of cables to a number m of cables, the numbers n and m being equal or different.

Preferably, the diameter of the bare face 26 of the electrode is substantially equal to or greater than the longitudinal dimension of the insulating means 18.

Other embodiments of the device and of the control method according to the invention will be described below with reference to Figures 2 to 7. In these figures, similar elements are designated by identical references.

In Figure 2, there is shown a device for controlling the electrical tightness of the insulating means 18, according to a second embodiment of the invention, designated by the general reference 10A.

In this case, the electrode 24A, housed inside the enclosure 20, is tubular and comprises a conductive hollow body 42, delimited by a solid wall of generally cylindrical shape, the external lateral surface of which can be coated with a conventional electrical insulation 44.

The insulating means 18 of the cable splice 12 are intended to be housed inside the hollow body 42, substantially coaxial with the latter. The terminals of the voltage generator 38 are connected to the cylindrical body 42 and to the core 14 of the cable 12.

The electrical tightness of the insulating means 18 is checked in a similar manner to the process using the device 10 illustrated in the figure. 1, observing the electroluminescent discharge éven¬ tuelle using conventional means of visual access to the interior of the enclosure 20 arranged in the axis of the hollow body 42 of the electrode. Preferably, the body 42 of the electrode has an internal diameter of 10 mm and a length of 60 to 120 mm substantially equal to or greater than the length of the insulating sleeve 18.

In the example illustrated in Figure 2, the ionizable gas is air at a pressure between 1 and 10 millibars absolute approximately, the voltage across the generator being between 500 V and 5000 V so as to cause, in in the event of an electrical leakage of the insulating means 18, an electroluminescent discharge between these insulating means and the internal surface of the body 42 of electrodes. The discharge is generally stable but can be fleeting in some cases.

As a variant, the hollow body of the electrode 24A can be delimited by a grid. Of course, the electrode 24A does not include an insulator in this case.

FIG. 3 shows a device for controlling the electrical tightness of the insulating means 18 according to a third embodiment of the invention, designated by the general reference 10B. In this case, the device 10B comprises two identical electrodes 46,47 arranged through circular orifices 48 formed in opposite walls of the enclosure 20.

Each electrode 46, 47 has a body 50 of generally cylindrical shape, preferably made of aluminum, extending longitudinally through the corresponding orifice 48.

The lateral surface of the electrode body 50 is coated with a conventional electrical insulator 52. Sealing means of known type, comprising for example an O-ring 54, are interposed between the external contour of each electrode 46, 47 and the internal contour of the corresponding orifice 48. The electrodes 46, 47 are substantially coaxial and have two opposite faces 56, inside the enclosure 20, in contact with the ionizable gas, and two faces 58, outside the enclosure 20, separated from the ionizable gas 22. Preferably, the spacing between the two electrodes 46,47 is between 5 and 35 mm.

The electrical tightness of the insulating means 18 is checked by placing the latter inside the enclosure 22 between the two electrodes 46, 47, in line with the faces 56, the cable 12 passing through this enclosure 22 right through, as in the case of devices 10, 10A illustrated in Figures 1 and 2.

The external faces 58 of the electrodes 46, 47 are connected to the terminals of a generator 60 of direct voltage. The electrodes thus form a cathode 46 and an anode 47 between which the gas 22 ionizes and forms a permanent plasma for the duration of the control. The plasma is visible in the form of a stable electroluminescent discharge extending substantially in a cylindrical volume separating the two electrodes, delimited by the circular inner faces 56 of the electrodes.

These internal faces 56, in contact with the gas 22, make it possible to obtain a plasma of high density around the insulating means 18. The cylindrical body 50 of the electrodes 46,47, passing through the walls of the enclosure 20, forms conduc¬ thermal teurs allowing the calories, produced by the electroluminescent discharge to be evacuated inside the enclosure 20, towards the outside of this enclosure. The device 10B further comprises an electrical circuit 62 for controlling the electrical tightness of the insulating means 18, connecting the conductive core 14 of the cable 12 and the electrode 46 forming the cathode. The circuit 62 comprises an ammeter 64 connected in series with a dipole 66 making it possible to establish a voltage difference between the conductive core 14 and the cathode 46. In the example illustrated in FIG. 3, the dipole 66 is a DC voltage generator. Preferably, the ionizable gas 22 is air at a pressure between 1 and 50 millibars absolute, and the voltage difference between the two electrodes 46 is between 100 and 1200 V.

In the event of a leak in the insulating means 18, a current flows between the conductive core 14 and the cathode 46 as well as in the circuit 62. By measuring the intensity in this circuit 62 using the ammeter 64, it is possible to thus detecting a failure of ^one sealing insulating means 18. The device 10B has, in tests, to detect a defect of electrical insulation and sealing means 18 located in the bottom of a blind hole having a capillary section 0 , 17 mm ² and a depth of 10 mm, this fault being detected in a few seconds. As a variant, the circuit 62 can be connected to the conductive core 14 and to the anode 47.

Preferably, the enclosure 20 comprises conventional means of visual access to the interior of the enclosure 22. These means make it possible to locate on the insulating means 18, a possible leakage, by observa¬ 'a localized variation of the color distribution in the plasma, at the location of this defect.

Of course, as in the cases of embodiments illustrated in FIGS. 1 and 2, it is possible to control 1st the insulating means of the splices of several cables at the same time.

It is also possible to remove the orifices 34 for passage of the ends of the cables 12 and the sealing rings 36, and to arrange the cables 12 entirely inside the chamber 20. In this case, the conductive elements for connecting the cables to one electrode (conductive ends of cables, metal lugs) are sufficiently distant from the electrodes so as not to disturb the plasma formed between the two electrodes.

FIG. 4 shows a device for checking the electrical tightness of the insulating means 18, according to a fourth embodiment of the invention, designated by the general reference 10C.

This device 10C differs from the device 10B illustrated in FIG. 3, in that the dipole 66 is a resistance of approximately 17 kΩ.

The possible current flow in the circuit 62, in the event of a leak in the insulating means 18, is detected by measuring the intensity in the circuit 62 using the ammeter 64 and / or by measuring an electrical quantity. proportional to the intensity of the circuit 62, for example the voltage across the dipole 66, using a voltmeter 68.

FIG. 5 shows a device according to a fifth embodiment of the invention, designated by the general reference 10D, for the control of an electrically insulating coating, for example a conventional varnish, covering a conductive metal wire 70, for example copper.

In this case, the device 10D comprises known means making it possible to continuously scroll the wire 70 between two identical electrodes 72, 74 of the girdle 20. Preferably, the scrolling means are arranged outside the enclosure 20.

Referring to Figure 6, in which an electrode 74 is shown in more detail, it can be seen that it has a generally cylindrical stepped shape.

Each electrode 72,74 is preferably made of aluminum and has at one of its ends a diametrical projection 76 delimited by a face 78 elongated in the direction of travel of the wire 70, that is to say along the length of the wire 70.

Each electrode 74 is housed in a circular hole 80 formed in an insulating wall of the enclosure 20, provided with a bottom pierced with a diametrical lumen 82 through which the projection 76 is fitted. In this way, only the projection 76 of the electrode 72,74 is in contact with the gas 22 contained in the enclosure 20.

An O-ring seal 84 is interposed between the complementary contours of each electrode 72,74 and the corresponding hole 80. The ends of the wire 70 extend outside the enclosure 20, through orifices 86 formed in opposite walls of this enclosure. The passage openings 86 are connected to a vacuum circuit 88 of known type in order to maintain a reduced pressure inside the enclosure 20 relative to the pressure outside this enclosure.

The electrodes 72,74 are connected to the terminals of the DC voltage generator 60 so that a first electrode 72 forms a cathode and the second electrode 74 forms an anode. The wire 70 is connected to ground.

The difference in voltage between the electrodes 72, 74 causes ionization of the gas, in a similar manner to the devices according to the third and fourth embodiments described above. The plasma created between the two electrodes 72,74 extends substantially in a prismatic volume separating the two electrodes, delimited by the faces 78 opposite the electrodes. A voltmeter 90 connected to ground and to one of the electrodes 72, 74, for example the anode 74, makes it possible to detect a voltage proportional to the intensity of the current passing between the wire 70 and the anode 74, in the event of a fault. sealing of the insulating coating of the wire 70.

Preferably, the ionizable gas is air, the pressure of this gas is between 0.1 and 100 milli¬ absolute bars and the voltage across the generator 60 is between 100 and 1200 V.

The device 10D makes it possible to control the integrity of the insulating coating of the wire 70, while the latter continuously travels through the enclosure 22, by measuring the variations in the voltage across the terminals of the voltmeter 90 relative to a threshold of predeter¬ mined voltage corresponding to the absence of a leak in the coating, that is to say the absence of current flow between the wire 70 and the anode 74.

As a variant, a single electrode could be placed inside the enclosure 20, connect the DC voltage generator 60 to this electrode and to the conductive wire 70, and observe the appearance of a stable electroluminescent discharge between the wire 70 and the electrode, in the event of a leak in the coating of the wire, by means of visual access means inside the enclosure 20.

In FIG. 7, a device 10E is shown according to a sixth embodiment of the invention for checking the electrical tightness of a multispindle connector 92 of known type.

The device 10E comprises an electrode 24E of generally cylindrical shape similar to the electrode 24A shown in FIG. 2. The connector 92 to be checked is housed inside the hollow body 42 of the electrode.

This connector 92 has a connection end delimited by an insulating support 94 carrying several parallel female pins 96 connected in a manner known per se to a bundle F of sheathed wires 98. An insulating sheath 100 connects the peripheral edge of the support 94 to the rest of the bundle F.

The connector 92 is connected to a complementary control connector 102 comprising male pins 104 fitted into the female pins 96 corresponding. The male pins 104 are carried by a metal support 106, preferably made of aluminum, which electrically connects them. The control connector 102 is electrically isolated from the ionizable gas by an insulating housing 108.

The terminals of the voltage generator 38 are connected, one to the cylindrical body 42 and the other to the metal support 106 of the control connector. In this way, the electrode 24E and the conductive means of the controlled connector 92 (female pins 96 and metallic cores of the wires 98) are brought to different potentials.

The electrical tightness control of the insulating means of the controlled connector 92 (insulating support 94, sheath of the wires 98 and insulating sheath 100) is done in a similar manner to the process using the device 10A illustrated in FIG. 2, observing possible electroluminescent discharge using conventional means of visual access to the interior of the enclosure 20 arranged in the axis of the hollow body 42 of the electrode 24E.

Preferably, the part of the connector checked

92 which is most likely to have a leak is placed in line with metallic radial spikes 110 connected to the internal surface of the body hollow 42. These 110 centripetal points make it possible to optimize the formation of the electroluminescent discharge in the event of a leak. As a variant, only one point may be provided. In the example illustrated in Figure 7, the ionizable gas is air at a pressure between 1 and 50 millibars absolute approximately and the voltage across the generator is between 500 and 5000 V.

The invention is not limited to the embodiments described above.

In particular, the invention makes it possible to control the integrity of means for electrical insulation of very diverse objects, for example an electrical connector, a conductive plate coated with an insulating material such as resin, etc.

The control device according to the invention may include means for moving the object inside the enclosure, in front of an electrode, so as to present different surfaces of the object opposite this electrode.

The control device according to the invention may also include means with magnetic fields for guiding the plasma towards the object.

The cylindrical shape of the electrodes illustrated in particular in FIGS. 3 to 6 makes it easy to ensure sealing between them and the walls of the enclosure which they pass through, thanks to conventional O-rings.

However, the electrodes can have various shapes (planes, curves, etc.) making it possible to adapt the density of the plasma to the shape of the objects to be checked.

In particular, the tubular electrodes 24A and 24E of the second and sixth embodiments can have various cross sections other than circular, for example rectangular.

The tubular electrodes can also be made up of two separable parts at an axial junction plane so as to facilitate the introduction of the objects to be checked inside the electrodes.

The solid electrodes illustrated in particular in FIGS. 3 and 4 may have shapes other than cylindrical, for example parallelepipedic. Furthermore, these same electrodes may include conductive tips so as to obtain effects as described for the sixth embodiment of the invention.

The monitoring devices according to the invention illustrated in FIGS. 3 to 5 include electrodes of identical shapes between which is arranged at least one object to be checked. As a variant, it is possible to arrange an object to be checked between two electrodes of different shapes. The invention has many advantages.

It allows non-destructive testing of the integrity of electrical insulation means of an object comprising conductive means.

It also makes it possible to detect, in the insulating means, defects of very small dimensions, these defects possibly corresponding to non-through holes formed in the insulating means.

Once the object is placed in the enclosure containing the ionizable gas, the time for carrying out the control is very short. Indeed, generally this completion time does not exceed a few seconds.

Furthermore, the invention generally makes it possible to visualize the location of the fault in the insulating means, by virtue of a stable light-emitting discharge. localized or to a localized variation of the colors _{of the} plasma in which the object to be checked is immersed.

The electroluminescent discharge or the localized variation of the colors of the plasma, which occurs in a gas having a low pressure (ranging between 0.1 and 500 millibars), releases a quantity of energy much weaker than a dielectric breakdown which destroys general ¬ ment the controlled object.

Furthermore, even when the electroluminescent discharge is relatively fleeting (in the event of a very small leak), it lasts much longer than a dielectric breakdown and can therefore be observed easily.

Claims

CLAIMS 1. Method for checking the integrity of means for electrically isolating an object comprising conductive means, characterized in that: - the object (12; 70; 92) is placed in an ionizable gas ( 22), near at least one electrode (24; 24A; 46.47; 72.74), the pressure of this gas being between 0.1 and 500 millibars absolute;

- a voltage difference is established between the conductive means (14; 70; 96) and the electrode; and

- the possible passage of current between the conductive means (14; 70; 96) and the electrode (24; 24A; 24E; 46.47; 72.74) is observed due to a leak in the insulating means (18 ).

2. Method according to claim 1, characterized in that the ionizable gas comprises a gas chosen from air, neon, helium, argon, krypton, xenon, carbon dioxide and nitrogen and the distance between the object (12; 70) and the electrode is between 2 mm and 35 mm.

3. Method according to claim 1 or 2, the object (70) being filiform, characterized in that the object (70) is scrolled continuously in front of the electrode (72,74).

4. Method according to any one of claims 1 to 3, characterized in that the appearance of an electroluminescent discharge (40) between the object (12) and the electrode (24) is observed. ; 24A; 24E) due to the passage of current between the conducting means (14) and the electrode (24; 24A; 24E), in the event of a leak in the insulating means (18).

5. Method according to claim 4, characterized in that the voltage between the conductive means (14) and the electrode (24; 24A) is between 500 and 5000 V.

6. Method according to any one of claims 1 to 3, characterized in that:

- the object (12; 70) is placed between two electrodes (46,47; 72,74); - a voltage difference is established between the electrodes so as to ionize the gas and form a permanent plasma surrounding the object (12; 70) for the duration of the control; and

an electrical quantity proportional to the intensity of the current flowing between the conductive means (14; 70) and the electrode (46; 74) is measured, in the event of a leak in the insulating means (18).

7. Method according to claim 6, characterized in that the voltage between the two electrodes (46,47; 72,74) is between 100 and 2000 V.

8. Method according to claim 6 or 7, charac¬ terized in that the spacing between the two electrodes (46,47; 72,74) is between 5 and 35 mm.

9. Device for controlling the integrity of means for electrically isolating an object comprising conductive means, characterized in that it comprises an enclosure (20) containing an ionizable gas (22) whose pressure is between 0 , 1 and 500 millibars absolute, at least one electrode (24; 24A; 24E; 46.47; 72.74) housed in the enclosure, near which the object (12;

70; 92) is intended to be placed inside the enclosure, means (38; 60,66) for establishing a voltage difference between the conducting means (14; 70; 96) and the electrode , and means for observing the possible passage of current between the conducting means (14;

70; 96) and the electrode (24; 24A; 24E; 46.47; 72.74), corresponding to a leak in the insulating means (18).

10. Device according to claim 9, characterized in that the ionizable gas comprises a chosen gas among air, neon, helium, argon, krypton, xenon, carbon dioxide and nitrogen, and in that the distance between the object (12; 70) and the electrode is between 2 mm and 35 mm.

11. Device according to claim 9 or 10, characterized in that the electrode (24; 46,47) comprises a solid conductive body (25; 50), preferably made of aluminum, isolated from the ionizable gas (22) except on one of its faces (26,56), in contact with the ionizable gas, at the right of which the object (12) is intended to be placed.

12. Device according to any one of reven¬ dications 9 to 11, the object (70) being filiform, caracté¬ ized in that the electrode (72,74) has a face (78) to the right of which l the object (70) is intended to be placed, elongated along the length of the object (70).

13. Device according to claim 9 or 10, characterized in that the electrode (24A; 24E) comprises a conductive hollow body (42) delimited by a grid or a solid wall, the object (12; 92) being intended to be placed inside the body (42).

14. Device according to claim 13, charac¬ terized in that the electrode has a generally tubular shape and has two separable parts at an axial junction plane so as to facilitate the introduction of the object to be checked inside the electrode.

15. Device according to claim 13 or 14, the object to be checked being a multi-pin connector (92), characterized in that the means for establishing a voltage difference between the conductive means (96) and the electrode (24E ) comprise a complementary connector (102) intended to be connected to the connector (92) to be controlled so as to connect all the pins of this latter connector (92) to the same potential.

16. Device according to any one of claims 9 to 15, the object (12; 70) being filiform, characterized in that the enclosure (20) has orifices (34; 86) for passage of the ends of the object (12; 70).

17. Device according to claim lé, characterized in that the passage orifices (34) are provided with sealing means preferably comprising rings (36) of rubber surrounding the ends of the object (12).

18. Device according to claim 16, characterized in that the passage openings (86) are connected to a vacuum circuit (88), the device further comprising means for continuously scrolling the object (70) in front of the electrode (72,74).

19. Device according to any one of claims 9 to 18, characterized in that the means for observing the flow of current comprise means of visual access to the interior of the enclosure (20) allowing so much 'observe the appearance of an electroluminous discharge (40) between the object (12) and the electrode (24; 24A) due to the passage of current between the conductive means (14) and the electrode (24; 24A), in the event of a fault in the sealing means (18).

20. Device according to any one of reven¬ dications 9 to 12 or 16 to 18, characterized in that it comprises two electrodes (46,47; 72,74) housed inside the enclosure ( 20), between which the object (12; 70) is intended to be placed inside the enclosure (20), and a DC voltage generator (60) connected to the terminals of the electrodes (46,47 ; 72,74) in order to ionize the gas between these electrodes and form a permanent plasma around the object (12; 70) for the duration of the control.

21. Device according to claim 20, charac¬ terized in that the spacing between the two electrodes (46,47; 72,74) is between 5 and 35 mm.

22. Device according to claim 20 or 21, characterized in that the means for observing the current flow comprise an electrical control circuit (62) connecting the conducting means (14) of the object (12) and one of the electrodes ( 46) of potential different from that of the conducting means (14).

23. Device according to claim 22, charac¬ terized in that the electrical control circuit comprises an ammeter (64) connected in series with an electrical dipole (66) forming a resistor or generator of direct voltage.

24. Device according to claim 23, charac¬ terized in that the dipole (66) is an electrical resistance, the circuit further comprising a voltmeter (68) connected to the terminals of this dipole (66).

25. Device according to claim 20 or 21, characterized in that the conductive means (70) are connected to ground, and in that the means for observing the possible passage of current comprise a voltmeter (90) .connected between ground and an electrode (72,74).

26. Device according to any one of reven¬ dications 20 to 25, characterized in that it comprises means of visual access to the interior of the enclosure allowing¬ to observe a localized variation in the color of the plasma, in the event of a leak in the insulating means.

27. Device according to any one of reven¬ dications 9 to 26, characterized in that it further comprises at least one metal tip (110) connected to the electrode (24E), to the right of which is intended to be placed the part of the object (92) which is most likely to have a leak.