Abstract:
A system that finds breaches in solid insulation, as well as detecting insufficient air gaps between conductors. The invention solves problems in how to detect breaks in solid insulation by applying high voltages without damaging the solid insulation. The invention also overcomes limitations where the voltages required to detect an insufficient air-gap can cause damage to, or are difficult to apply to the electrical device under test. The system for testing conductors held physically separated or otherwise isolated from each other by an insulating material is composed of a high-voltage breakdown tester, a means of connecting the tester to the conductors, and an added gas that is used to displace air in the proximity of the conductors. Optionally additional conductors or probes are placed in proximity to the original conductors to: 1) find breaks in the solid insulation of one or more conductors, or 2) detect intended air-gaps or mechanical position in the DUT that have insufficient spacing to the additional conductors. The gas conducts current or arcs at a lower voltage gradient than air, which allows detection of insulation and isolation defects better and earlier than testing performed in ambient air conditions.

Description:
RELATED APPLICATIONS 
     This application claims the benefit of earlier-filed U.S. Patent Application No. 60/209,951, filed Jun. 7, 2000, for “Method and Device for Detecting and Locating Insulation/Isolation Defects Between Conductors,” which is incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to devices and methods used to detect defects in isolation and insulation in electrical wiring. More specifically, the present invention relates to devices and methods that detect defects in a specialized test gas environment. 
     2. Description of Related Art 
     Wires or cables typically have a conductor made from conductive material. Characteristically, conductive material is a class of material incapable of supporting electric stress, such that when a charge is given to a conductive material it spreads to all parts of the material. Exemplary conductive materials include aluminum, copper, platinum, gold, silver, chromium, tungsten, nickel, combinations thereof, and the like. 
     The conductors of wires are commonly coated with a solid insulating material primarily to provide electrical isolation between wires. In addition to its primary function, the solid insulation material also helps provide thermal insulation, strain relief, protection against mechanical damage and abrasion, chemical and corrosion protection, sealing, and limit signal distortion. The thickness and dielectric characteristics of this solid insulation are specifically chosen to maintain isolation, limit shock danger and signal distortion seen in the conductor. As wire is used for a wide variety of purposes, there are differences in the type of insulation used. For example, a data communication cable may use a Teflon® FEP coat to promote transmission and provide physical protection. 
     Occasionally the solid insulation surrounding conductive wires is damaged or defective. The damaged or defective solid insulation may expose the conductors. The damage or defects in the insulation may be very small and difficult to see. Defects, such as cracking, often results from mechanical stresses imposed upon conductors having brittle insulation. Embrittlement of the insulation is a result of the normal aging of the insulation. Aging is often accelerated by cable operation at high temperatures over an extended period of time. Mechanical stresses may be caused by short-circuit currents, thermal expansion and contraction of the conductors, movement of the conductor, and vibration. While the dielectric strength of insulation is not significantly reduced by brittleness alone, loss of isolation can result from the development of cracks. For this reason, close inspection of insulation should be made at frequent intervals, and repairs made as necessary. 
     More specifically, it is important to know if insulating material surrounding a conductive wire or cable has been pierced or broken. Such a defect could be a precursor to an electrical failure in the overall electrical system in which the wire or cable is installed. Similarly, isolated conductors, which are too close together, such as exposed pins in a connector or conductors in an automobile fuse box, may cause an electrical short circuit. Bent or damaged conductors may violate the air gap distances necessary to maintain isolation, thereby introducing a potential short circuit or flashover situation within the electrical system. Failures in the solid wire insulation or uncontrolled short-circuiting between exposed conductors have caused numerous accidents in aircraft and other vehicles. It is therefore desirable to find damaged insulation and verify conductor isolation before a failure occurs so that appropriate repairs can be made. 
     Unfortunately, the defect and fault detection methods presently available are counterproductive to the defect detection process. For example, high voltage is commonly used to find defects in solid insulation, but the voltage required to find these insulation defects is often higher than the voltage rating of the insulation. Thus the test itself can actually destroy or weaken the insulation and wiring being analyzed, thereby creating defects in the solid insulation. What is needed is a method of reducing the voltage required to detect defects and electrical isolation faults in the electrical pathways. 
     Furthermore, traditional high voltage testing methods may not be used for wiring located in fuel rich operational environments, such as near jet engines. Applying a high voltage in such an environment creates a substantial risk of combustion unless all of the fuel is removed prior to testing. Some testing methods, such as introducing an ion cloud without displacing the oxygen, actually increase the risk of a spark igniting the fuel. 
     Accordingly, what is needed is an improved technique for testing insulation and isolation defects in electrical wiring. In particular, the test should not compromise the integrity of the wiring being tested nor be the cause of additional damage to the wiring. Additionally, a method of testing wiring for defects in unstable environments, such as a fuel rich jet engine environment, without generating a substantial risk of combustion is needed. 
     SUMMARY OF THE INVENTION 
     The present invention provides a system and method of detecting breaches in solid insulation and detecting insufficient air gaps between conductors. The invention performs these detections in a specialized gas environment tailored for high voltage defect sensor applications. The present invention has been developed in response to the current state of the art, and in particular, in response to these and other problems and needs that have not been fully or completely solved by currently available sensor or electronic detection applications. The present invention reduces the amount of high voltage required to detect an insulation or isolation defect when performing a high-voltage breakdown test. These qualities are primarily accomplished through injection of a test gas into the area around the electrical pathway or conductor being tested. Exemplary test gases useful with the present invention include neon, helium, argon, xenon, krypton, radon, and combinations thereof. Helium, for example, has been shown to require a lower voltage gradient than air requires (e.g., at 1500 V and at atmospheric pressure, an arc occurs at approximately 0.009 short-inch in air versus 0.4 inch in helium), and is an excellent choice for the test gas. 
     The lower voltage gradient of an easily ionized test gas when compared to ambient air helps the system check the solid insulation around wires and cables at a lower voltage potential. The test gas is directed or confined such that it envelops the area to be tested. When high voltage is applied between conductors that are exposed and physically close, a corona forms or an arc occurs between the conductors through the test gas. A testing device may record electrical noise or a current surge between the conductors. Prior to arcing, the added test gas exhibits a very high electrical resistance. Once a sufficient voltage gradient is applied, the test gas “breaks down” or ionizes and has very low effective resistance. With the lower resistance it is easier for an electrical arc to form between the conductors. In an effort to promote this effect at a lower voltage, the voltage gradient for the breakdown of the test gas used in the present invention is substantially lower than for ambient air. 
     Several configurations are available to test the electrical isolation of the cables in a gas-enriched test environment. One configuration uses a gas-containment shroud to maintain the gas enriched test environment. The gas containment shroud may be flexible and conform to the curvature of the electrical cables. The gas containment shroud may also be transparent, thereby making visible any corona activity around the electrical cables. 
     A high voltage breakdown tester places sufficient voltage potential across the conductors to detect insufficient isolation or defective insulation. An alternative configuration introduces at least one conductive probe into the shroud environment. The probe is connected to a tester and moved along the conductors. A defect in the insulation is detected when current flow is detected because of an arc between the probe and the conductors being tested. The arc occurs at the location of a defect in the isolation or insulation of a conductor, specifically where the voltage potential between the probe and the exposed conductor overcomes the voltage gradient required for electrical breakdown of the test gas. The application of the test gas by a gas source to a localized region of the conductors enclosed by the gas containment shroud may also be synchronized with a current-sense module on the high voltage breakdown tester to locate an isolation or insulation fault. 
     Using the characteristics of the test gas, the present invention may also verify the air gaps or required distance between isolated conductors separated by air. Exemplary air gaps include the pins in a connector or exposed conductors in an automobile fuse box. In the present invention, when a pin in a connector is bent, the applied voltage will promote arcing between the closest pins alerting a monitoring test device of the potential short circuit between wires. 
     Additionally, the system may also be used in fuel rich environments with a substantially lower risk of explosion. As the injected test gas displaces oxygen in the testing area, less oxygen is available for combustion. At certain concentrations of gas there is insufficient oxygen for combustion to occur. The concentration of the test gas in the testing area may be controlled in part by a gas containment shroud, which restricts the movement of the test gas away from the testing area. 
     The present invention reduces the amount of high voltage required to detect an insulation or isolation defect. The present invention detects the location of insulation defects without damaging the conductor being tested. The present invention allows the safe application of a high-voltage breakdown test for air gaps and insulation defects in fuel rich environments. The present invention enhances the sensitivity of a high-voltage breakdown test with respect to air gaps between conductors in a localized region. As such, the present invention helps verify the required distance between isolated conductors separated by ambient air, such as the pins in a connector or exposed conductors in an automobile fuse box. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In order that the manner in which the above recited and other advantages and objects of the invention are obtained, a more particular description of the invention briefly described above will be rendered by reference to specific embodiments thereof, which are illustrated in the appended drawings. Understanding that these drawings depict only typical embodiments of the invention and are not therefore to be considered to be limiting of its scope, the invention will be described and explained with additional specificity and detail through the use of the accompanying drawings in which: 
     FIG. 1 illustrates one embodiment of a gas insulation and isolation defect detection system in accordance with the present invention; 
     FIG. 2 illustrates an alternative embodiment of a gas insulation detection system with a conductive gas containment shroud; 
     FIG. 3 illustrates a probe for use with an embodiment of the insulation detection system; and 
     FIG. 4 illustrates an isolation defect detection system for monitoring conductors in a connector. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The figures and the following discussion are intended to provide a brief, general description of a suitable operating environment in which the invention may be implemented. The figures are intended to be illustrative of potential systems that may utilize the present invention and is not to be construed as limiting. Those skilled in the art will appreciate that the invention may be practiced with many types of configurations, including electrical circuitry, wiring, cables, and the like. 
     Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment. 
     Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided, such as examples of test gases, various gas delivery and containment systems, different electrode probes, high voltage breakdown testers, types of insulation, etc., to provide a thorough understanding of embodiments of the invention. One skilled in the relevant art will recognize, however, that the invention can be practiced without one or more of the specific details, or with other methods, components, materials, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the invention. 
     Reference throughout this specification to “gas” or “test gas” means a state of matter in which the molecules are practically unrestricted by cohesive forces and require a lower voltage gradient for ionization than ambient air requires. The test gases are referred to herein as electropositive. As such, the electropositive test gases exhibit an ionization point, breakdown, flashover, arcing, or corona discharge at a lower voltage gradient relative to ambient air. Exemplary test gases useful with the present invention include neon, helium, argon, xenon, krypton, radon, and combinations thereof either at atmospheric or reduced pressure. Helium, for example, has been shown to require a lower voltage gradient than air requires before causing a noticeable voltage event, such as arcing or corona discharge, and is an excellent choice for the test gas. Using 1500 Volts at atmospheric pressure to test for voltage events, an arc occurs at approximately 0.009 inch in air versus 0.4 inch in helium. Under these test conditions, an environment flooded with helium exhibits about {fraction (1/40)} th  the voltage gradient of the same environment flooded with air. The noble test gases listed above have the added benefit that they are generally not chemically combining even during an arc. Other electropositive gases, which may or may not chemically combine with conductors and/or insulation, may also be used. 
     “Ionization” is the process by which neutral atoms or groups of atoms become electrically charged, either positively or negatively, by the loss or gain of electrons. An “ionized test gas” denotes the state of the test gas when atoms or groups of atoms within the test gas have become charged. The test gases may initially be introduced into the test area in a non-ionized state, but the test gas still requires a lower inducing voltage than ambient air for the occurrence of a noticeable voltage event, such as arcing or corona discharge. 
     Reference throughout this specification to “cable” or “wire” means a conductor or bundle of conductors with or without insulation. Conductors are made from electrically conductive material. Characteristically, conductive material is a class of material incapable of supporting electric stress, such that when a charge is given to a conductive material it spreads to all parts of the material. Exemplary conductive materials include aluminum, copper, platinum, gold, silver, chromium, tungsten, nickel, combinations thereof, and the like. 
     Reference is first made to FIG. 1 illustrating an isolation defect detection system  100  or environment in which the present invention may be utilized or implemented. The system  100  includes a high-voltage breakdown tester  110  connected via wires  120  to test the integrity of the solid insulation  130  of the wires  140 ,  150 . The high-voltage breakdown tester  110  also tests the isolation of the electrical paths created by conductors  145 ,  155  for electrical signals. Exemplary conductors or electrical paths that may be tested by the present invention include cables, connectors, wire harness, backplanes, printed circuit boards, circuitry, or other similar electrical apparatus. While FIG. 1 only illustrates two wires  140 ,  150 , one skilled in the relevant art will recognize, however, that the system may also be practiced with multiple conductors. 
     As previously mentioned, the conductors  145  and  155  generally include at least one coating of solid insulation  130  to prevent arcing between neighboring conductors. Insulation applied directly over conductors  145  and  155  is often called the primary insulation, since it determines most of the transmission properties of an individual conductor. Sheath insulation, commonly called the jacket, brings several conductors together in a single cable configuration. The sheath insulation predominately offers mechanical protection. However, it does affect the electrical performance of the cable. Exemplary insulation materials used in data communication cables include FHF film (Teflon® FEP), Halar ECTFE, Compounded PVC, and other polymer resins. Other insulation systems for conductors include impregnated fiber products, laminated and molded products, polyester film, polyamide film, adhesive tapes, composite products, insulating paper, mica products, fiberglass sleeving, fiberglass tape, polyester non-woven fabrics, thermoplastic systems (asphalt-mica), thermosetting systems (polyester-mica or epoxy-mica), and other compounds know to one of skill in the art. 
     During testing, high voltage is applied between the conductors  145 ,  155  via wires  120  electrically attached to the high-voltage breakdown tester  110 . In one embodiment of the present invention, the high voltage breakdown tester  110  further includes a high voltage supply and a current-sense module. The tester  110  is used to determine the amount of electrical isolation between conductors  145  and  155 . The high voltage breakdown tester  110  performs a “hipot test” by applying a high voltage (AC or DC) potential between conductors  145  and  155  and sensing the current flow (AC or DC). The high voltage supply may provide between about 50 Volts and about 15,000 Volts. More preferably, the high voltage supply at atmospheric pressure provides between about 150 Volts and about 3000 Volts. The amount of current sensed or the current change over time is used to determine the quality of insulation or isolation between conductors  145  and  155 . If multiple conductors are being tested for insulation/isolation, patterns may be used to apply the voltage between conductors such that all conductors to be tested for insulation/isolation defects have voltage applied between them at some time during the test. 
     In the presence of a test gas, the high-voltage breakdown tester  110  senses the current flow that identifies arcs or faults between exposed conductors  160  and  170 . The test gas is emitted into a gas containment shroud  180 . The application of the test gas by a gas source to a localized region of the conductors enclosed by the gas containment shroud  180  may be synchronized with the current-sense module to locate an isolation or insulation fault. 
     In one embodiment, gas emission into the shroud  180  is delivered from a gas source  185  via a manifold  187  to at least one orifice  190 . As the test gas enters the shroud  180  via the orifices  190 , the test gas envelops a test area adjacent the conductors to be tested. In the presence of the test gas supplied by the gas source  185 , the voltage potential required for current flow is substantially less than ambient air. Accordingly, one advantage of the present invention is the reduction of the amount of high voltage required to detect an insulation or isolation defect when performing a high-voltage breakdown test. 
     The system  100  retains the gas in the vicinity of the wires  140  and  150  via the gas containment shroud  180 . Many devices can be used as a gas containment shroud  180  to constrain the concentration of the added gas, such as a container, box, bag, pillow, jet, rigid metallic form or guide, basin, flexible pipe, membrane, semi porous urethane barrier, balloon, sealed room, chassis, conductive fabric, and the like. These devices may or may not be used as part of the system  100  to emit the test gas. In the embodiment of FIG. 1, the test gas is directed towards the shroud  180  via the manifold  187  leading from the gas source  185 . The test gas is dispersed within the shroud  180  via multiple orifices  190 . The orifices  190  are preferably located in the vicinity of the desired test area. In one configuration the gas source  185  supplies the test gas under pressure, allowing the test gas to saturate the test area quickly. As the test gas expands under normal atmospheric conditions a high concentration of test gas molecules displace the ambient air. 
     The system  100  uses test gases that are electropositive, enabling voltage events, such as corona discharge or arcing, to be observed at lower voltage levels than ambient air. Preferably, these voltage levels are within the voltage rating of the insulation being tested. However, any lower voltage potential reduces risk of damage to the conductive wire and its insulation. The test gas exhibits a very high electrical resistance until the tester  110  applies a sufficient voltage gradient across the conductors  145  and  155 . 
     Once a sufficient voltage gradient is applied, the test gas “breaks down” or ionizes and has very low effective resistance. With the lower resistance it is easier for an electrical arc to form between the exposed conductors  160  and  170 . In an effort to promote this flashover effect at a lower voltage, the voltage gradient for the breakdown of the test gas used in the present invention is substantially lower than for ambient air. Exemplary gases useful with the present invention include neon, helium, argon, xenon, krypton, radon, and combinations thereof. 
     Lower voltages can be used to find insulation/isolation defects with the test gas than without the test gas. Alternatively, the same voltage applied with a test gas can sense greater gaps than without the gas. This process can be applied equally to new conductors or conductors that are installed into their final application such as installed wiring in an aging aircraft. Since an arc is most likely to occur in the region of the gas, the gas may be applied to all or part of the conductor to locate specific defects. 
     Reference is next made to FIG. 2, an isolation defect detection system  200  that uses a conductive gas containment shroud  280  to help identify insulation defects and isolation faults in conductors is shown. The system  200  includes a high-voltage breakdown tester  210  connected via wires  220  to the cables  240 ,  250  to be tested. The high-voltage breakdown tester  210  is also connected via wire  225  to the conductive gas containment shroud  280 . The cables  240 ,  250  include conductive core materials  245  and  255  each covered substantially by solid insulation  230 . High voltage is applied between the conductors  245  and  255  and the conductive gas containment shroud  280  via wires  220  and  225  attached to the high-voltage breakdown tester  210 . This configuration is useful when singular insulation defects need to be detected, as the exposed conductor  270  will arc to the conductive gas containment shroud  280 . 
     An electropositive test gas is emitted into the conductive gas containment shroud  280  through jet  290  from a gas source  285  via a manifold  287 . The test gas envelops the area surrounding the conductors to be tested and also contacts the conductive gas containment shroud  280 . The jet  290  concentrates the level of the test gas in the test area. In the presence of the test gas, a high voltage arc occurs between exposed conductor  270  and the conductive shroud  280 . Sensing the current flow in wires  220  and  225  from the arc, the high-voltage breakdown tester  210  identifies the fault. The accuracy of this testing procedure may be improved by synchronizing the release of the test gas with the application of the inducing voltage to the test area. 
     An alternative embodiment utilizes a manifold design similar to that illustrated in FIG.  1 . The manifold allows the test gas to enter the conductive shroud through multiple openings. One skilled in the relevant art will also recognize, however, that many different gas distribution systems are known in the art and may be used without departing substantially from the invention. For example, the invention may also be practiced using multiple jets or inlets. 
     As previously mentioned, the test gas is electropositive, such as neon, helium, argon, xenon, krypton, radon, and combinations thereof. These gases do not need to be ionized prior to introduction into the test area. Furthermore, the system  200  does not require the use of a conductive ion stream or cloud, nor is an external ion generator necessary. Specifically, the test gas exhibits a very high electrical resistance until the tester  210  applies a sufficient voltage gradient across the wires  220  and  225 . If a defect exists in the electrical system being tested, the gas “breaks down” or ionizes around the defect and has very low effective resistance once a sufficient voltage gradient is applied. With the lower resistance it is easier for an electrical arc to form between the exposed conductor  270  and the conductive shroud  280 . As previously mentioned, to promote arcing at a lower voltage, the voltage gradient for the breakdown of the test gas used in the system  200  is substantially lower than for ambient air. 
     FIG. 3 is an insulation defect detection system  300  that uses a probe  360  to find insulation/isolation faults. The defect detection system  300  includes a high voltage breakdown tester  310  electrically connected via wires  320  to cables  340  and  350 . More specifically, the tester  310  is electrically connected to the conductors  345  and  355 . The tester  310  is also electrically connected via wire  325  to a probe  360 . During testing, the probe  360  is brought near cables  340  and  350  and used in conjunction with the test gas to detect the exposed conductor  370 . The system  300  also includes a gas containment shroud  380  to retain the gas introduced for testing. 
     The probe  360  includes both an external electrode/conductor and a mechanism for introducing the test gas into the test area. The external conductor, such as probe tip  365 , is typically concealed within a gas nozzle or jet  390  to ensure isolation and reduce the risk of accidental contact with the probe tip  365  during the high voltages tests. The probe  360  is designed to deliver gas to the test area through the jet  390 . As such, the test gas concentration is localized to the vicinity of the test probe  360 . The jet  390  is supplied gas via the manifold  387  from the gas source  385 . The probe  360  may improve overall test efficiency and reduce the amount of gas necessary to detect the exposed conductor  370  by synchronizing the release of the gas with the initiation of electrical testing. By combining gas delivery and detection functions into the probe  360 , the system  300  is even more effective at finding insulation/isolation faults using the high voltage breakdown test. 
     In one embodiment, the gas is delivered using a gas delivery system separate from the probe as illustrated in FIGS. 1 and 2. In this configuration, the probe is introduced into the test environment after the gas has saturated the test area. An alternative system configuration employs a conductive shroud as illustrated in FIG. 2 with the probe. An alternative configuration uses the manifold and multiple orifice shroud illustrated in FIG.  1 . 
     The probe  360  increases the sensitivity of a hipot test to the insulation/isolation characteristics of a cable assembly by bringing an exposed conductive electrode  365  within the probe  360  close to the defect in solid insulation  330 . Specifically, the high voltage breakdown tester  310  detects current flow between wires  320  and  325  as the probe  360  approaches the exposed conductor  370 . Using the probe  360  further decreases the voltage needed in the test gas to find an insulation/isolation fault. 
     Additionally, the system  300  may also be used in fuel rich environments with a substantially lower risk of explosion. As the injected gas displaces oxygen in the testing area, less oxygen is available for combustion. At certain concentrations of test gas there is insufficient oxygen for combustion to occur. The concentration of the test gas in the testing area may be controlled in part by the gas containment shroud  380 , which restricts the movement of the gas away from the testing area. The lower voltage requirement of the probe configuration improves the overall safety factor of the test in fuel rich environments. 
     The present invention enhances the sensitivity of a high-voltage breakdown test to air gaps between conductors in a localized region. FIG. 4 illustrates a localized air gap detection system  400  used to test conductive pins  440  of a connector  430  for positional faults. A high-voltage breakdown tester  410  is connected to the conductive pins  440  of the connector  430  via wires  420 . A gas source  485  may supply a test gas to displace the air in the vicinity of the connector  430 . In one embodiment, the test gas supplied by the gas source  485  is non-ionized. The test gas emits from a nozzle  490  onto the test area to reduce the voltage potential necessary to detect mechanical position errors of the conductive pins  440 . The emission of the test gas from the nozzle  490  may be synchronized with the high-voltage breakdown tester  410  so that the gas is present before the inducing voltage is applied. The conductive pins  440  are selectively connected to the high-voltage breakdown tester  410 . If multiple conductive pins  440  are being tested for insulation/isolation, patterns may be used to apply the voltage between pins  440  such that all pins  440  to be tested for insulation/isolation defects have voltage applied between them at some time during the test. When the high voltage breakdown tester  410  applies the necessary voltage potential to the conductive pins  440 , bent pin  470  will arc through the gas to one of the adjacent conductive pins  440 . The high-voltage breakdown tester  410  detects the arc by the current flow. An effective way of testing the connector is to synchronize the release of the test gas with the application of the inducing voltage to the various conductive pins  440 . 
     Using the characteristics of the test gas, the system  400  may also verify the air gaps or required distance between isolated conductors. Exemplary air gaps include the pins  440  in a connector  430  or exposed conductors in an automobile fuse box. Often small variations in pin positioning are imperceptible and would be difficult to detect without system  400 . In the illustrated example, the positional error of the bent pin  470  violates the isolation standards for the connector  430  and could short circuit during use, not to mention the substantial risk of misconnection. 
     Another embodiment places multiple conductive probes close to the conductors being tested, each probe being attached to the high-voltage breakdown tester to detect isolated insulation failures. With high-voltage applied to the conductors and additional probes, the gas will breakdown (arc) where the probes are in close proximity to the defect. The increased current sensed by the high-voltage breakdown tester will indicate that a fault has occurred. In this way, the high-voltage breakdown tester can be used to identify which conductors failed, and the gas and/or additional probes may optionally be localized and traversed along the conductors to identify the specific location of the fault. 
     In summary, the present invention reduces the amount of high voltage required to detect an insulation or isolation defect by introducing a test gas into the test area. By reducing the voltage necessary, the present invention may detect the location of insulation defects without damaging the conductor being tested. The present invention also allows the safe application of a high-voltage breakdown test for air gaps and insulation defects in fuel rich environments. The present invention enhances the sensitivity of a high-voltage breakdown test with respect to air gaps between conductors in a localized region. As such, the present invention helps verify the required distance between isolated conductors separated by ambient air, such as the pins in a connector or exposed conductors in an automobile fuse box.