Abstract:
The invention concerns an electrical connection member, characterised in that it is capable of detecting discontinuities in an electrical network and comprises a casing having at least three branches, each of the branches comprising, at the end of same, at least one terminal for electrical connection to a respective piece of equipment, and least one main conductor linking two terminals at the ends of two branches in the casing, at least one secondary conductor linking at least one terminal of the end of the third branch in the casing, and comprising an electrical coupler designed to inject an electrical test signal from the secondary conductor into the main conductor, and to transmit, to the secondary conductor, an electrical response signal generated by the reflection of the electrical test signal against a discontinuity encountered in the electrical network.

Description:
GENERAL FIELD 
       [0001]    The invention relates to the field of detection of faults in an electrical network, especially that of detection of discontinuities by reflectometry. 
       PRIOR ART 
       [0002]    To detect a fault on an electrical conductor which transports a supply or datum signal, one solution is reflectometry. An electrical test signal is injected into the electrical conductor using a reflectometer. In the presence of a discontinuity in the electrical conductor, this test signal is partially reflected and returned to the reflectometer. 
         [0003]    A conductor typically comprises a conductive core enclosed by an insulating sheath and comprises a contact (male or female) at each of its ends. 
         [0004]    The electrical conductors in most electrical installations are grouped together to form a mono-wire, two-wire, three-wire cable, etc., and a plurality of cables is assembled in a harness. 
         [0005]    At each of its ends, a harness therefore has a plurality of contacts intended to be electrically connected to a plurality of contacts of another equipment. 
         [0006]    To inject a test signal, it generally proves necessary to disconnect one of the ends of the harness containing the electrical conductor to be tested to gain access to a contact of this conductor. 
         [0007]    After disconnection of the connector, location of a fault by reflectometry and repair of the defective conductor, it is necessary to conduct operating test of the system or equipment which was electrically connected to the defective conductor but also on all systems and equipment whereof the supply conductors pass through the connector uncoupled by the fault. 
         [0008]    Also, intermittent faults can appear in an electrical installation subject to vibrations, for example in the power supply network of an aircraft. But these intermittent faults therefore cannot be detected during tests conducted while the aircraft is undergoing maintenance on the ground. 
         [0009]    To avoid such disconnections, it has been proposed to utilise current induction injection clamps. 
         [0010]      FIG. 1  shows an injection clamp P known from the prior art. The clamp P is adapted to clamp an electrical cable to be tested by reflectometry. The clamp emits coupling by electromagnetic radiation to the clamped conductor and generates a test signal which spreads to the conductor. 
         [0011]    However, this type of clamp is not adapted for testing harnesses of cables provided with electromagnetic protections, which do not let this radiation pass between the exterior and the interior of the cable. These protections must be removed prior to the test, or even destroyed if the design of the protections has not planned for this possibility; this extends the duration and magnifies the cost of intervention. 
         [0012]    Also, harnesses can comprise a large number of electrical cables held clamped to each other. However, the introduction of a clamp such as that illustrated in  FIG. 1  risks damaging conductors adjacent to that intended to be tested: first the cables are generally joined together by a fret or a pipe clamp which has to be cut (first damage risk), and also the conductors then have to be pulled away and the injection clamp has to be placed (second damage risk). 
         [0013]    The clamps such as the clamp P cannot be placed on twisted cables, for example two-wire, three-wire, etc., without untwisting the cable by having previously pulled out and then reseated the contact of the connector. 
       PRESENTATION OF THE INVENTION 
       [0014]    The aim of the invention is to conduct tests involving injection of a signal into an electrical network without having to disconnect or damage any element of the electrical network. 
         [0015]    For this purpose an electrical connector is proposed, characterized in that it is capable of detection of discontinuities in an electrical network and comprises:
       a body having at least three branches, each of the branches comprising at its end at least one terminal for electrical connection to a respective equipment,   at least one primary conductor connecting in the body two terminals to the ends of two branches,   at least one secondary conductor connecting in the body at least one terminal of the end of the third branch and comprising an electrical coupler adapted to inject into the primary conductor an electrical test signal originating from the secondary conductor, and to transmit to the secondary conductor an electrical response signal generated by reflection of the electrical test signal on a discontinuity found in the electrical network.       
 
         [0019]    The invention especially conducts tests by simple connecting of a reflectometer to a secondary end of the member, and therefore reduces the cost and duration of a detection test for faults such as short circuits or open circuits. 
         [0020]    Also, the member conducts reflectometry tests on an electrical line when operating. This is particularly advantageous as discontinuities can appear in some electrical installations subject to perturbations when they are operating, for example in the electrical supply network of an aircraft. The connector detects discontinuities occurring during aircraft flight, or even discontinuities appearing only intermittently, which are very difficult or even impossible to detect during ground testing. 
         [0021]    The invention also relates to a kit for detection of discontinuities in an electrical network, the kit comprising an electrical connector as per the preceding description and a reflectometer electrically connected to at least one terminal of a secondary end of the member. 
     
    
     
       DESCRIPTION OF FIGURES 
         [0022]    Other characteristics, aims and advantages of the invention will emerge from the following description which is purely illustrative and non-limiting and which must be considered in conjunction with the appended drawings, in which: 
           [0023]      FIG. 1 , already discussed, illustrates an injection clamp known from the prior art. 
           [0024]      FIG. 2  is an exterior side view of an electrical connector according to a first embodiment. 
           [0025]      FIG. 3  is a frontal view of an end of the electrical connector of  FIG. 2 . 
           [0026]      FIG. 4  is a sectional view of the electrical connector shown in  FIG. 2 . 
           [0027]      FIG. 5   a  is a perspective view of a coupler according to a second embodiment. 
           [0028]      FIG. 5   b  is a view in partial section of an electrical connector comprising couplers according to the second embodiment. 
           [0029]      FIG. 6  schematically illustrates an electrical network tested by reflectometry using an electrical connector according to the invention. 
       
    
    
       [0030]    In all figures, similar elements have identical reference numerals. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0031]    In reference to  FIG. 2 , an electrical connector  1  for equipment comprises an body  10 . 
         [0032]    The body  10  ensures electromagnetic and/or mechanical and/or lightning and/or hermetic protection of elements housed in the inner housing  12 . 
         [0033]    In the embodiment illustrated in  FIG. 2 , the body  10  has a central portion  14  and several tubular branches  16   a - 16   c.    
         [0034]    Each branch  16   a - 16   c  extends from the central portion  14  to an end  18   a - 18   c  of the member  1  intended to be connected to a respective equipment. The ends have respective connecting axes of parallel directions. 
         [0035]    A first branch  16   a  extends from the central portion  14  in a direction Xa. A second branch  16   b  and a third branch  16   c  extend from the central portion  14  in directions Xb, Xc opposite the direction Xa of the first branch  16   a , forming a Y-shaped body  10 . 
         [0036]    Each end  18   a - 18   c  comprises at least one terminal or electrical connection contact  182   a - 182   c.    
         [0037]    Of the ends of the member  1 , two at least are called primary ends, and one at least is called secondary. 
         [0038]    Each primary end  18   a ,  18   b  is intended to be electrically connected by means of terminals to a respective electrical equipment A, B. 
         [0039]    The secondary end  18   c  is intended to be electrically connected by means of terminals to a device  2  configured to detect discontinuities in the network R, for example a reflectometer. 
         [0040]    According to an embodiment illustrated in  FIG. 3 , each primary end  18   a ,  18   b  has a planar and substantially circular transversal surface  180 . The connecting terminals  182   a  are distributed over the planar surface  180 , and can form a housing or else protrude relative to the planar surface. Each terminal  182  is adapted to be electrically connected with an element of complementary volume present on an equipment (not illustrated) intended to be connected to the member  1 . 
         [0041]    The secondary end  18   c  can be made similarly. 
         [0042]    Also, each end  18   a - 18   c  can comprise complementary mechanical connecting means  19  to keep in place the electrical link set up between each terminal  182   a - 182   c  of the member  1  and each complementary element of the corresponding connected equipment. 
         [0043]    For example, the end has a bezel forming a base and an outer thread. The thread is intended to receive a complementary plug while the bezel is intended to fix the connector to a structure or equipment. 
         [0044]    In reference to  FIG. 4 , the member  1  also comprises an inner housing  12  connected to each end of the member  1 . 
         [0045]    The member  1  comprises at least two electrical conductors  20 ,  30  extending in the inner housing  12 . Each electrical conductor can typically be a cable comprising a core and a protective sheath extending about the core. 
         [0046]    The member  1  comprises at least one primary conductor  20  connecting a first primary terminal  182   a  of a first primary end  18   a , with a second terminal  182   b  of a second primary end  18   b . Each primary conductor  20  is provided to transport an electrical signal between the first terminal  182   a  and the second terminal  182   b.    
         [0047]    The member  1  also comprises at least one secondary conductor  30  housed in the inner housing  12 . The secondary conductor  30  is connected both to at least one secondary terminal  182   c  present on a secondary end  18   c  of the member  1 , and also to an electrical coupler  40  also housed in the inner housing  12 . Each secondary conductor  30  is provided to transport an electrical signal between a corresponding secondary terminal  182   c  and a coupler  40 . 
         [0048]    In the embodiment illustrated in  FIG. 4  showing a Y-shaped body  10 , the end  18   a  opposite the ends  18   b  and  18   c  is a primary end  18   a ,  18   b . Each electrical coupler  40  is associated with a primary conductor  20 . 
         [0049]    Each coupler  40  is adapted to inject into the associated primary conductor  20  an electrical test signal originating from the connected secondary conductor  30 . 
         [0050]    Each coupler  40  is also adapted to detect a test signal which transits in a primary conductor  20 , and to transmit the third electrical signal to the connected secondary conductor  30  as far as the corresponding secondary terminal. 
         [0051]    In an embodiment illustrated in  FIGS. 4 and 6 , the member  1  comprises a primary conductor  20 , a secondary conductor  30  connected to a coupler  40 , which coupler  40  is linked to the primary conductor  20 . 
         [0052]    More precisely, the coupler of the embodiment illustrated in  FIG. 4  is a capacitive coupler comprising a condenser  44  directly connected to a junction point  22  of the primary conductor  20 , for example by welding. The condenser  44  can typically be a film or tantalum condenser. 
         [0053]    The electrical coupler  40  can also comprise a filter  46  adapted to let through the electrical test and response signals, and to filter a functional electrical signal which transits over a primary conductor  20 . The filter  46  can be for example a high-pass filter  46  adapted to filter a low-frequency functional signal which transits via the primary conductor  20 . 
         [0054]    The filter  46  can be a component placed on the secondary conductor, upstream or downstream of the condenser  44 . In another embodiment, not illustrated, the condenser and the filter are one and the same component; the condenser is adapted to ensure the filtering described. The member  1  can be used to detect faults in an electrical network. 
         [0055]    In reference to  FIG. 6 , the member  1  is electrically connected to a first equipment A by its first primary end  18   a , to a second equipment B by its second primary end  18   b . A common electrical network R comprising at least the devices A, B and the primary conductor  20  of the member  1  is created. 
         [0056]    The member  1  is also electrically connected by its secondary end  18   c  to a device  2  intended to detect discontinuities in the common network R, such as a reflectometer. 
         [0057]    The member  1  and the reflectometer  2  together constitute a kit for detecting discontinuities in the electrical network R. 
         [0058]    In a first detection mode, none of the first and second equipment A, B connected to the member  1  delivers an electrical signal to the member  1 ; no functional electrical signal transits over the primary conductor  20  of the member  1 . 
         [0059]    At the start of the test, the reflectometer  2  delivers an electrical test signal to the secondary terminal  182   c  to which it is connected. 
         [0060]    This electrical test signal is transported to the secondary electrical conductor  30 , then injected into the primary conductor  20  at the junction point  22  by means of the coupler  40 . 
         [0061]    The test signal spreads to the first primary terminal  182   a , then to the first connected equipment A; it also propagates to the second primary terminal  182   b , in the connected second equipment B. 
         [0062]    The test signal finds a discontinuity D in the network R (here present in the first equipment A). Some of the energy of the test signal is reflected by the discontinuity D, generating an electrical response signal in the direction of the junction point  22 . 
         [0063]    The electrical reflected response signal reaches the junction point  22 , is transmitted to the secondary conductor  30  by means of the coupler  40 , reaches the secondary terminal  182   c  and is finally captured by the connected reflectometer  2 . 
         [0064]    In a second detection mode, the equipment are operating: a functional electrical signal circulates in the common network R. 
         [0065]    This functional signal comes from one of the first or second equipment A or B; it can be for example a supply signal generated by the first connected equipment A, or a data signal. 
         [0066]    If the coupler  40  comprises a filter  46  such as described previously, the functional signal is not transmitted to the secondary conductor  30 . The secondary conductor  30 , and the device  2  connected at the secondary end  18   c , are therefore insulated from the functional electrical signal. 
         [0067]    When the reflectometer  2  delivers an electrical test signal, this test signal is injected into the primary conductor  20  via the coupler  40  and is superposed on the functional electrical signal. 
         [0068]    Also, the response signal reflected by the presence of a discontinuity in the common network is also superposed to the functional electrical signal. 
         [0069]    The response signal is transmitted by the electrical coupler  40  to the secondary conductor  30 , then to the reflectometer, but not the functional signal which is filtered so as not to damage the reflectometer. 
         [0070]    In another embodiment illustrated in  FIGS. 5   a  and  5   b , the coupler  40  is an inductive coupler. Although not illustrated, the inductive coupler can comprise a filter  46  such as described previously. 
         [0071]    The inductive coupler  40  comprises a winding  42  and a magnetic element  43 . 
         [0072]    The magnetic element  43  extends right around a portion of a primary conductor  20 . It typically has a toric form. 
         [0073]    The secondary conductor  30  is a wire comprising a portion wound according to a direction of rotation about a portion of the magnetic element  43 , the wound portion forming a winding  42 . 
         [0074]    The conductor also comprises two portions of wire  32   a ,  32   b  each joined to the winding  42  and to a secondary terminal  182   c  of the secondary end  18   c.    
         [0075]    When a test signal output by the reflectometer reaches the winding  42 , the winding  42  creates a magnetic field channeled by the magnetic element  43 . The circulation of this field about the primary conductor  20  creates an electrical test signal which propagates to the primary conductor  20 . 
         [0076]    When an inductive coupler is used there is no transmission of electrical signal by contact at a welding point, but by radiation (coupling). 
         [0077]    The inductive coupler is preferably configured to create a magnetic field of orientation parallel to the primary conductor  20  to improve transmission of electrical signal by coupling. For this to happen, a magnetic element  43  of toric form can be arranged so that its axis is parallel to the primary conductor, and the winding can be wound around the magnetic element in a direction substantially parallel to the primary conductor. 
         [0078]    If the primary conductor  20  comprises a core protected by a sheath, there is no need to strip this sheath at any junction point to ensure electrical communication between the winding  42  and the primary conductor  20 , since the sheath of the primary conductor  20  is adapted to be traversed by the electromagnetic radiation emitted by the winding  42 . 
         [0079]    The two portions of wire  32   a ,  32   b  of each secondary conductor  30  can be twisted together to prevent couplings by crosstalk between several secondary conductors. 
         [0080]    In the embodiment illustrated in  FIG. 5   b , the member comprises three primary conductors  20 ,  20 ′,  20 ″, three respective windings  42 ,  42 ′,  42 ″, and three respective magnetic elements  43 ,  43 ′,  43 ″. 
         [0081]    The primary conductors  20 ,  20 ′,  20 ″ extend parallel in the inner housing  12 . 
         [0082]    In the illustrated embodiments, each coupler  40  is associated with a respective single primary conductor  20 . A test signal delivered by the device  2  will therefore test one electrical line only. 
         [0083]    In another embodiment, each coupler  40  can be associated with several primary conductors. So one and the same test signal sent by a reflectometer will spread to several primary conductors, which reduces the duration of the test. 
         [0084]    For example, a winding  42  as per the second embodiment can enclose several primary conductors, and send out electromagnetic radiation which will reach all the enclosed primary conductors. 
         [0085]    The connector  1  can be used in an electrical network embedded in an aircraft, or in any other type of installation subject to the appearance of intermittent or permanent discontinues. 
         [0086]    The functional signal can be a supply signal. 
         [0087]    Supply signals presently used in aircraft are of continuous frequency, or between 360 Hz and 800 Hz, typically 400 Hz. In this context, the filter  46  can have a capacity of 33 nF whereof the cutoff frequency is 100 kHz. The filter  46  will let through test and response signals whereof the frequency is greater than 100 kHz and will block the frequency supply signal less than 100 kHz. 
         [0088]    In an embodiment, the functional signal can be a data signal. In this case, the coupler  40  and the filter  46  if present will be dimensioned to exhibit impedance which does not perturb the transmission of data. 
         [0089]    Each secondary end  18   c  can be permanently connected to a reflectometer  2  which could be regularly requested to detect discontinuities in the common electrical network, for example during flight of an aircraft. 
         [0090]    In an embodiment, each secondary end  18   c  can be intermittently connected to a reflectometer  2 . In this case, the member  1  can comprise removable mechanical and/or electrical insulation means  17  placed on the secondary end  18   c  to prevent the introduction of dust, fluid, etc. via the secondary terminals in the member  1  and secure the electrical installation when no device  2  is connected to the secondary end  18   c.    
         [0091]    These insulation means  17  can be adapted to cooperate with the mechanical connecting means  19  present on the secondary end  18   c . For example, the insulation means are caps and the mechanical connecting means are threads on the outer surface of the body  10 . 
         [0092]    The member  1  can of course have more than one secondary branch and more than two principal branches  16   a ,  16   b.    
         [0093]    Also, in the embodiments of body  10  in a Y-shape illustrated in the figures, the first branch extending in the direction Xa is a primary end  18   a ,  18   b . In another embodiment, the end  18   a  opposite the two other ends can be a secondary end  18   c.    
         [0094]    Other orientations of branches for a member  1  having three branches  16   a - 16   c  are also possible, for example a T-shape (in which the axes connecting two branches are joined), or else a star shape having three branches (each connecting axis forms an angle of 120° with each of the two other connecting axes).