Patent Publication Number: US-11037700-B2

Title: LCDI power cord system and method

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present continuation-in-part application is related to, claims the earliest available effective tiling date(s) from (e.g., claims earliest available priority dates for other than provisional patent applications; claims benefits under 35 USC§ 119(e) for provisional patent applications), and incorporates by reference in its entirety all subject matter of the following listed application(s) (the “Related Applications”) to the extent such subject matter is not inconsistent herewith; the present application also claims the earliest available effective filing date(s) from, and also incorporates by reference in its entirety all subject matter of any and all parent, grandparent, great-grandparent, etc. applications of the Related Application(s) to the extent such subject matter is not inconsistent herewith: 
     U.S. provisional patent application 63/013,742, entitled “LCDI Shield Continuity Monitoring Circuits”, naming Victor V. Aromin as first inventor, filed 22 Apr. 2020. And U.S. patent application Ser. No. 16/935,895 which claims priority from U.S. provisional patent application 62/876,960, entitled “Power Cord”, naming Victor V. Aromin as first inventor, filed 22 Jul. 2019; and U.S. provisional patent application 62/880,970, entitled “Power Cord”, naming Victor V. Aromin as first inventor, filed 31 Jul. 2019. 
    
    
     BACKGROUND 
     1. Field of Use 
     This invention relates to a power cord. In particular, it relates to a power cord for an appliance that has a built-in leakage current detection and interruption (LCDI) conductor for detecting a leakage current in the power cord. 
     2. Description of Prior Art (Background) 
     With the wide use of household electrical appliances, such as air conditioners, washing machines, refrigerators, etc, more attention is being paid to the safety of using such appliances. An appliance typically has a power cord of one meter or longer. As shown in  FIG. 1 , such a power cord is made of three copper wires  11 ,  6  and  8  for carrying power, three insulating layers (made of rubber or plastic)  10 ,  5 , and  7  surrounding the respective copper wires, two metal sheaths  19  and  14  (made of thin copper wires woven together) surrounding two insulating layer, respectively, and an outer insulating layer  1  (made of rubber or plastic) enclosing the wires. 
     Such a power cord may age due to long-term use, or become damaged when the appliance is moved, which may cause a leakage between the phase line and the neutral or ground lines in the cord. Such leakage current may cause sparks, which may cause fire and property damages. To quickly and accurately detect leakage current in the power cord, an additional conductor is provided and electrically connected to the metal sheath  19 ,  14 . Leakage current can be detected by detecting a voltage on the metal sheath. The metal sheaths are conventionally made by weaving thin copper wires. The cost of the power cord has increased due to the increase cost of the copper material. 
     Another prior art solution is shown in  FIG. 2 . A power cord includes three copper wires  11 ,  6  and  8  for carrying power and a leakage current detection conductor  3  for detecting a leakage current in the power cord. As before the three copper wires  11 ,  6  and  8  are surrounded by three insulating layers (made of rubber or plastic)  10 ,  5 , and  7 , respectively. Two insulating layers  10 ,  5  are surrounded by metal conductive layers  9 ,  4 , respectively. The leakage current detection conductor  3  is provided adjacent the two metal conductive layers  9 ,  4  and is in contact with both of them. A metal sheath  2  encloses the three wires with their respective insulating layers and metal conductive layers as well as the leakage current detection conductor  3 . An outer insulating layer  1  (made of rubber or plastic) is provided outside of the metal sheath  2 . 
     The metal conductive layers  9 ,  4  may be made of a thin copper foil, tin foil, aluminum foil, or conductive rubber. The leakage current detection conductor  3  may be formed of one or more copper wires or aluminum wires. When leakage current is present between copper wires  11  and  6 ,  11  and  8 , or  6  and  8 , the leakage current detection conductor  3  can detect the leakage current via the metal conductive layers  9  or  4 . As shown in  FIG. 2 , this prior art solution requires another conductive sheath  2  surrounding all the cables and the detection conductor  3 . 
     BRIEF SUMMARY 
     Accordingly, the present invention provides a power cord useful for appliances such as air conditioners, washing machines, refrigerators, etc. which has a built-in leakage current detection conductor for detecting a leakage current in the power cord. 
     In accordance with one embodiment of the present invention an alternating current (AC) power cord is provided. The AC power cord includes a neutral wire assembly, having an insulated conductive neutral wire and a conductive neutral wire shield surrounding the insulated neutral wire insulator. The conductive neutral wire shield includes a conductive side and a non-conductive side and is wrapped around the insulated neutral wire with the conductive side facing outwards. The AC power cord includes a conductive flexible media wrapped around the conductive side of the neutral wire shield. The AC power cord also includes a line wire, assembly, wherein the line wire assembly includes a conductive shield having a conductive side and a non-conductive side and is wrapped around the insulated line wire with the conductive side facing inwards. The conductive neutral wire shield and the conductive line wire shield are connected in series at one end of the AC power cord. 
     The invention is also directed towards an alternating current (AC) power cord having an insulated neutral wire, an insulated line wire, an insulated return wire, and a ground wire. Also included is a conductive shield surrounding the insulated neutral wire, the insulated line wire, the insulated return wire, and the ground wire. The conductive shield includes an outwardly facing conductive side and an inwardly facing non-conductive side. A conductive flexible media surrounds the conductive side of the conductive shield. The conductive flexible media and the return wire are connected in series at one end of the power cord. 
     In accordance with another embodiment of the present invention an AC power cord is presented. The AC power cord includes an insulted neutral wire surrounded by a conductive neutral wire shield having a conductive side and a non-conductive side. The conductive side of the neutral wire shield faces outwards. Surrounding the neutral wire shield is a conductive flexible media. The AC power cord also includes an insulted line wire surrounded by a conductive line wire shield having a conductive side and a non-conductive side. The conductive side of the line wire shield faces outwards. Surrounding the line wire shield is a second conductive flexible media. The conductive line wire shield and the conductive neutral wire shield are connected in series at one end of the AC power cord. 
     In Accordance with another embodiment of the present invention Leakage Current Detection Interrupter (LCDI) circuit for interrupting AC power from an AC source is provided. The LCDI circuit is electrically connectable to an insulated neutral wire surrounded by a neutral wire shield (NWS) and an insulated line wire surrounded by a line wire shield (LWS). The LCDI circuit also includes a power supply circuit for supplying a rectified waveform and a floating load connected to the power supply circuit. The floating load connected to the power supply circuit includes a leakage current detection circuit (LCDC) for detecting leakage current from the insulated neutral wire or the insulated line wire and a shield integrity circuit (SIC) for monitoring the NWS and LWS integrity. 
     The invention is also directed towards a method for constructing a power cord and circuit for detecting and interrupting line voltage between an alternating current (AC) line end and a load end of the power cord upon detection of a power cord fault. The method includes providing an insulated conductive neutral wire between the load end and AC line end of the power cord and wrapping the insulated conductive neutral wire with a neutral wire shield having a conductive side of the neutral wire shield facing out. The method includes wrapping a conductive flexible media around the conductive side of the neutral wire shield. The method further includes providing and line wire shield having a conductive side and a non-conductive side an insulated conductive line wire and wrapping the line wire shield around a tinned wire and an insulated line wire with the conducting side facing in and in electrical contact with the tinned wire. The method includes connecting the tinned wire to the conductive flexible media in series at the load end of the power cord. The method further includes interrupting line voltage if current between the insulated line or insulated neutral wire and any one of the shields is detected; and/or includes interrupting line voltage if shield integrity is compromised or otherwise broken, such as, for example, a break in a shield or corrosion. The method also includes providing a rectifying power supply circuit for energizing the neutral wire shield with a voltage. 
     In accordance with another embodiment of the present invention a method for interrupting AC line voltage between an alternating current (AC) line end and a load end of a shielded power cord upon detection of a power cord fault is provided. The method includes providing a leakage current detection circuit (LCDC) for detecting AC leakage current from the power cord and interrupting line voltage between the AC line end and the load end of the shielded power cord if leakage current is detected. The method includes connecting the LCDC and SIC to the shielded power cord and providing a power supply circuit (PSC) for energizing the LCDC, SIC, and the shielded power cord with a voltage. Providing the LCDC further includes providing a bi-stable latching device having an on/off state and a charge holding device connected to a controlling port of the bi-stable latching device; such as, for example, a transistor base or an SCR gate port. The method includes, during normal operation, charging the charge holding device to a charge less than the trigger charge needed to trigger the bi-stable latching device to its on-state, but of sufficient charge to minimize the time needed to trigger the device if a fault is detected and to minimize damaging inrush current. The method further includes providing a shield integrity circuit (SIC) for monitoring shielded power cord integrity and interrupting line voltage between the AC line end and the load end of the shielded power cord if shield integrity is compromised. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The subject matter which is regarded as the invention is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other objects, features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which: 
         FIG. 1  is a cross-sectional view showing the structure of a conventional power cord; 
         FIG. 2  is a cross-sectional view showing the structure of another conventional power cord with a leakage current detection conductor; 
         FIG. 3  is a cut away side view showing the structure of a power cord with leakage current detection conductors according to an alternate embodiment of the present invention; 
         FIG. 3A  is a cross-sectional view showing the structure the power cord shown in  FIG. 3 ; 
         FIG. 3B  is a cut away side view showing the structure of a power cord with leakage current detection conductors according to an alternate embodiment of the present invention; 
         FIG. 3C  is a cross-sectional view showing the structure the power cord shown in  FIG. 3B ; 
         FIG. 3D  is a cut away side view showing the structure of a power cord with leakage current detection conductors according to an alternate embodiment of the present invention; 
         FIG. 3E  is a cross-sectional view showing the structure the power cord shown in  FIG. 3D ; 
         FIG. 4  is a cut away side view showing the structure of a power cord with leakage current detection conductors and an immersion detection cable according to an embodiment of the present invention; 
         FIG. 4A  is a cut away side view showing the structure of a power cord with leakage current detection conductors and a twisted pair immersion detection cable according to an embodiment of the present invention; 
         FIG. 5  is a circuit block diagram of a LCDI circuit connectable to the power cords shown in  FIG. 1 ,  FIG. 2 ,  FIG. 3 ,  FIG. 3A-E ; 
         FIG. 6  is a block diagram of a LCDI circuit connectable to the power cords shown in  FIG. 4  or  FIG. 4A ; 
         FIG. 7  is a detailed schematic diagram of the block diagram shown in  FIG. 5 ; 
         FIG. 8  is an alternate schematic diagram of the block diagram shown in  FIG. 5 ; 
         FIG. 9  is a detailed schematic diagram of the block diagram shown in  FIG. 5 ; 
         FIG. 10  is an alternate schematic diagram of the block diagram shown in  FIG. 5 ; 
         FIG. 10A  is an exploded partial view of a circuit connection of the return wire shown in  FIGS. 3B-E ; 
         FIG. 11A  is a waveform diagram for the normal condition of the Shield Integrity Circuit (SIC) shown in  FIG. 7  or  FIG. 8 ; 
         FIG. 11B  is a waveform diagram for the fault condition of the SIC shown in  FIG. 7 ; 
         FIG. 11C  is a waveform diagram for the fault condition of the SIC shown in  FIG. 8 ; 
         FIG. 12A  is a waveform diagram for the normal condition of the SIC shown in  FIG. 9  or  FIG. 10 ; 
         FIG. 12B  is a waveform diagram for the fault condition of the SIC shown in  FIG. 9 ; 
         FIG. 12C  is a waveform diagram for the fault condition of the SIC shown in  FIG. 10 ; 
         FIG. 13  illustrates a flow diagram of a method for constructing a power cord for detecting and interrupting line voltage between an AC line end and a load end of the power cord in accordance with the present invention; 
         FIG. 13A  illustrates a flow diagram of an alternate method for constructing a power cord for detecting and interrupting line voltage between an AC line end and a load end of the power cord in accordance with the present invention; 
         FIG. 13B  illustrates a flow diagram of a second alternate method for constructing a power cord for detecting and interrupting line voltage between an AC line end and a load end of the power cord in accordance with the present invention; 
         FIG. 14A  is a waveform diagram for the normal condition of the Leakage Current Detection Circuit (LCDC) shown in  FIG. 7  or  FIG. 8 ; and 
         FIG. 14B  is a waveform diagram for the normal condition of the Leakage Current Detection Circuit (LCDC) shown in  FIG. 9  or  FIG. 10 . 
     
    
    
     DETAILED DESCRIPTION 
     The following brief definition of terms shall apply throughout the application: 
     The term “comprising” means including but not limited to, and should be interpreted in the manner it is typically used in the patent context; 
     The phrases “in one embodiment,” “according to one embodiment,” and the like generally mean that the particular feature, structure, or characteristic following the phrase may be included in at least one embodiment of the present invention, and may be included in more than one embodiment of the present invention (importantly, such phrases do not necessarily refer to the same embodiment); 
     If the specification describes something as “exemplary” or an “example,” it should be understood that refers to a non-exclusive example; and 
     If the specification states a component or feature “may,” “can,” “could,” “should,” “preferably,” “possibly,” “typically,” “optionally,” “for example,” or “might” (or other such language) be included or have a characteristic, that particular component or feature is not required to be included or to have the characteristic. 
     Referring now to  FIG. 3  and  FIG. 3A  of the drawings, there is shown a cut away side view showing the structure of a power cord  400  with leakage current detection conductors according to an alternate embodiment of the present invention. In this embodiment the power cord  400  includes a neutral wire or cable  45 , a line wire or cable  48 , and a ground wire  46 . Each of the wire or cables is surrounded by an insulator layer  43 ,  49 , and  492 . In addition, the insulating layers  492  and  43  of the line wire  48  and the neutral wire  45 , respectively, are each surrounded by a shield; a conductive medium,  41  and  42 , respectively. It is appreciated that the conductive medium  41 ,  42  has a conductive side and a non-conductive or less conductive side. The conductive medium  41 ,  42  may be an aluminum foil shielding comprising a thin layer of aluminum and mylar composite tape. The conductive side of conductive medium  41  is facing inwards and the less, or non-conductive side of the conductive medium is facing inwards. The conductive side of conductive medium  42  is facing outwards. 
     Still referring to  FIG. 3  and  FIG. 3A  power cord  400  also includes a solid tin copper wire  495  disposed between conductive medium  41  and insulator  492 . The conductive side of conductive medium  42  is surrounded by a conductive flexible media  44 . The conductive flexible media  44  may be any suitable conductive flexible media woven to cover 30% of the surface area of the conductive side of conductive medium  42  per unit length. At least one end of the conductive flexible media  44  may be connected to an LCDI circuit  494 . In addition, at least one end of the wire  495  may also be connected to the LCDI circuit  494 . The conductive flexible media may be any suitable conductive material such as, for example: conductive coatings, tapes, ribbons, a braided copper flexible media, or a conductive flexible media woven from conductive material such as, but not limited to, high-performance carbon fiber/gold/copper composite wire, conductive graphene wire, or conductive graphene yarn. 
     It is understood that any if insulators  492  or  43  become defective and current leaks to the conductive side of conductive medium  41  or  42  the current flows through conductive flexible media  44  or wire  495  where it is detected by LCDI circuit  494  and interrupt power between a line source and load. 
     Referring also to  FIG. 3B  and  FIG. 3C  of the drawings, there is shown a cut away side view showing the structure of a power cord  3 B 400  with leakage current detection conductors according to an alternate embodiment of the present invention. In this embodiment the power cord  3 B 400  includes a neutral wire or cable  45 , a line wire or cable  48 , ground wire  46  and a return wire  3 B 01 . Each of the wire or cables is surrounded by an insulator layer  43 ,  49 ,  492  (as shown in  FIG. 3A ) and  3 B 49 . The insulated wires  45 ,  46 ,  48  and  3 B 01  are surrounded wrapped by a shield; i.e., a conductive medium,  3 B 42 . It is appreciated that the conductive medium  3 B 42  has a conductive side and a non-conductive or less conductive side. The conductive medium  3 B 42  may be an aluminum foil shielding comprising a thin layer of aluminum and mylar composite tape. The conductive side of conductive medium  3 B 42  is facing outwards and the less, or non-conductive side of the conductive medium is facing inwards towards the center of power cord  3 B 400 . 
     Still referring to  FIG. 3B  and  FIG. 3C , the conductive side of the conductive medium  3142  is surrounded by a conductive flexible media  3 B 44 . The conductive flexible media  3 B 44  may be any suitable conductive flexible media woven to cover 30% of the surface area of the conductive side of the conductive medium  3 B 42  per unit length. At least one end of the conductive flexible media  44  may be connected to an LCDI circuit  3 B 494 . In addition, at least one end of the return wire  3 B 01  may also be connected to the LCDI circuit  3 B 494 . The conductive flexible media may be any suitable conductive material such as a copper flexible media, or a conductive flexible media woven from conductive material such as, but not limited to, high-performance carbon fiber/gold/copper composite wire, conductive graphene wire, or conductive graphene yarn. 
     Referring also to  FIG. 3D  and  FIG. 3E  of the drawings, there is shown a cut away side view showing the structure of a power cord  3 C 400  with leakage current detection conductors according to an alternate embodiment of the present invention. In this embodiment the power cord  3 C 400  includes a neutral wire or cable  45 , a line wire or cable  48 , ground wire  46  and a return wire  3 B 01 . Each of the wire or cables is surrounded by an insulator layer  43 ,  49 , and  492 . In addition, the insulating layers  492  and  43  of the line wire  48  and the neutral wire  45 , respectively, are each surrounded by a shield, a conductive medium,  3 C 42  and  3 C 42 A, respectively. It is appreciated that each of the conductive mediums  3 C 42  and  3 C 42 A has a conductive side and a non-conductive or less conductive side. The conductive medium  3 C 42  and  3 C 42 A may be an aluminum foil shielding comprising a thin layer of aluminum and mylar composite tape. The conductive side of each of the conductive mediums  3 C 42  and  3 C 42 A is facing outwards. 
     Still referring to  FIG. 3D  and  FIG. 3E  the conductive side of the conductive mediums  3 C 42  and  3 C 42 A is surrounded or wrapped by conductive flexible medias  3 C 44  and  3 C 44 A. The conductive flexible medias  3 C 44  and  3 C 44 A may be any suitable conductive flexible media woven to cover 30% of the surface area of the conductive side of the conductive mediums  3 C 42  and  3 C 42 A  2  per unit length. At least one end of the conductive flexible medias  3 C 44  and  3 C 44 A may be connected to an LCDI circuit  3 D 494 . In addition, at least one end of the return wire  3 B 01  may also be connected to the LCDI circuit  3 D 494 . The conductive flexible medias  3 C 44  and  3 C 44 A may be any suitable conductive material such as a copper flexible media, or a conductive flexible media woven from conductive material such as, but not limited to, high-performance carbon fiber/gold/copper composite wire, conductive graphene wire, or conductive graphene yarn. 
     Referring also to  FIG. 4  there is shown a cut away side view showing the structure of a power cord  401  with leakage current detection conductors as described earlier and an immersion detection cable  407  comprising a conducting wire  405  surrounded by an absorbent covering  406 . The immersion detection cable  407  is arranged within the power cord  401  to be in close contact with conductive flexible media  44  and/or conductive medium  42 . In this embodiment, moisture absorbed by the absorbent covering  406  completes an electrical connection between conducting wire  405  and conductive flexible media  44  and/or conductive medium  42 . As is described in more detail herein, the LCDI circuit  494 A detects the electrical connection between conducting wire  405  and conductive flexible media  44  and/or conductive medium  42  and interrupt power between a line source and load. 
     Referring also to  FIG. 4A  there is shown a cut away side view showing the structure of a power cord  401 A with leakage current detection conductors as described earlier and a twisted pair immersion detection cable  407 A according to an embodiment of the present invention. The twisted pair immersion detection cable  407 A includes conducting wires  405 A and  405 B, each surrounded by an absorbent covering  406 A and  406 B, respectively. In this embodiment, moisture absorbed by the absorbent covering  406 A and  406 B completes an electrical connection between conducting wires  405 A and  405 B and/or between conducting wires  405 A or  405 B and conductive flexible media  44  and/or conductive medium  42  and interrupt power between a line source and load. As is described in more detail herein, the LCDI circuit  494  detects the electrical connection and interrupt power between line source and load. 
     Referring also to  FIG. 5  there is shown a circuit block diagram of a LCDI circuit  50  connectable to the power cords shown in  FIG. 1 ,  FIG. 2 ,  FIG. 3 , or  FIG. 3A . LCD circuit  50  includes line shield  513 , neutral shield  515 , switch  518 , power supply circuit  512 , leakage current detection circuit (LCDC)  516 , solenoid  519 , and shield integrity circuit (SIC)  514 . As shown herein the LCDE  516  and the SIC  514  comprise a floating load with respect to the power supply  512 . SIC  514  includes SIC controller  514 A and SIC switch  514 B. LCDC  516  includes LCDC switch  517 A. Shield  515  is constructed and provided in accordance with any of the shields described earlier. As is described in more detail herein, when manual reset switch  518  is set line voltage is connected to LOAD and to power supply circuit  512  via solenoid  519 . Power supply circuit  512  supplies bias voltages to LCDC  517 , SIC  514 , and shields  513  and  515 . Shields  513  and  515 , having load ends,  513 A and  515 A, respectively, are connected in series at their load ends. Power supply  512  is connected to shield  513  at its source end  513 B; and, LCDC  517  and SIC  514  are connected to shield  515  at its source or line end  515 B. As is discussed and shown in more detail herein, the SC  514  allows a small amount of solenoid current to flow through solenoid  519  but less than the energizing current needed to energize solenoid  519  to disengage manual reset switch  518 . It is appreciated that not starting from zero energizing current allows solenoid  519  to energize faster when a fault is detected. 
     Referring also to  FIG. 6  there is shown a block diagram of a LCDI circuit  60  connectable to the power cords shown in  FIG. 4  or  FIG. 4A . It is well known that two dissimilar metals in electrical contact, such as conductive flexible media  44  and conductive layer  42 , in the presence of an electrolyte, such as water, begins to galvanically corrode. Thus, IDC  66 , connected to SIC  514  causes AC line power to be disconnected from the load if moisture is detected by IDC  66 . Immersion detection cable (IDC)  66  can be either the immersion detection cable  407  or the twisted pair immersion detection cable  407 A described earlier. 
     Still referring to  FIG. 6 , LCDI circuit  60  also includes light detection circuit (LDC)  64  connected to SIC  514 . In the presence of light impinging on circuit  60 , implying that circuit  60  is exposed to the elements, SIC  514  causes AC line power to be disconnected from the load if light is detected by LCD  64 . 
     Referring also to  FIG. 7  there is shown a detailed circuit  70  of the block diagram  50  shown in  FIG. 5 . LCDI circuit  70  includes line shield  513 , neutral shield  515 , switch  518 , power supply circuit  712 , leakage current detection circuit (LCDC)  716 , solenoid  519 , and shield integrity circuit (SIC)  714 . Shield  515  includes conductive layer  42  surrounded by conductive flexible media  44  described earlier. As is described in more detail herein, when manual reset switch  518  is set line voltage is connected to LOAD and to power supply circuit  712  via solenoid  519 . Power supply circuit  712  supplies bias voltages to LCDC  717 , SIC  714 , and shields  513  and  515 . As is discussed and shown in more detail herein, the SIC  714  allows a small amount of solenoid current to flow through solenoid  519  but less than the energizing current needed to energize solenoid  519  to disengage manual reset switch  518 . It is appreciated that not starting from zero energizing current allows solenoid  519  to energize faster when a fault is detected. 
     Still referring to  FIG. 7  and  FIGS. 11A-11B . When switch  518  is mechanically (manually) engaged AC line voltage is connect to LOAD. 60 Hz AC line voltage is also connected to power supply circuit  712  via solenoid  519 . Power supply circuit  712 , comprising bridge rectifier (diodes D 1 -D 4 ) outputs a rectified unsmoothed DC signal at A. The rectified unsmoothed DC signal at A is routed through R 6  to LCDC  717  and SIC  714 , via shields  513  and  515  connected in series. 
     R 6  drops the amplitude of rectified unsmoothed DC signal at A to a predetermined amplitude at B. Voltage dividers R 3 /R 7  drops the amplitude of rectified unsmoothed DC signal at B to a predetermined amplitude at C. Under normal conditions, the voltage amplitude at C, the gate of SCR 2  LCDC switch  517 A, is insufficient to trigger SCR 2  into an on condition. It will be appreciated, however, that C 3  charges to a voltage determined by R 3 , R 7  to maintain a minimum voltage on the gate of SCR 2 . (See  FIG. 14A  for full wave rectification and  FIG. 14B  for half wave rectification.) If an adverse leakage condition occurs, e.g., arcing from AC line voltage to either shield  513  or  515 , the gate voltage at C rises from the charge on C 3  to trigger SCR 2  into an on-condition. In the SCR 2  on, or conducting condition, current flow through solenoid  519  is increased to a solenoid energizing level to disengage manual reset switch  518  and interrupt power between AC line source and load. Again, it is appreciated that not starting from zero gate voltage allows SCR 2  to trigger faster when a fault is detected than if the gate voltage was starting from zero volts. It is also understood that inrush current can exceed the current carrying capability of board connectors as well as PCB traces, resulting in damaging the connectors and traces. Thus, maintaining a minimum C 3  charge minimizes inrush current and potential circuit damage in the event of an arcing condition. 
     Still referring to  FIG. 7 , the rectified unsmoothed DC signal at B is routed to the base of npn transistor Q 1 , SIC controller  514 A, via R 2  (see  FIG. 11A ), biasing Q 1  into an on condition during the positive cycle of the rectified unsmoothed DC. When Q 1 (B) voltage drops below V BE  Q turns off and the voltage at Q 1 (C), SIC switch  514 B, is near 0 v due to the unsmoothed DC signal at A dropping to near 0 v in the cycle. When the unsmoothed DC signal at A swings positive, Q 1  is again biased on, dropping the unsmoothed DC signal at A across R 8 , keeping Q 2  in an off condition during normal operation. 
     Still referring to  FIG. 7 , it is understood that under normal conditions the rectified unsmoothed DC signal at A is dropped across resistor R 8  and that R 8  is sized to allow an amount of AC current less than the SOL 1   519  energizing current to flow through R 8  through Q 1  back to neutral when Q 1  is conducting. During Q 1 &#39;s off state, or non-conducting state, SOL 1   519  inductively opposes the change in current until Q 1  again turns on, thus maintaining, or nearly maintaining the current flow through SOL 1   519 . It is understood and appreciated that the small amount of solenoid current flowing through solenoid SOL 1   519  is less than the energizing current needed to energize solenoid  519  to disengage manual reset switch  518 . It is further appreciated that not starting from zero energizing current allows solenoid  519  to energize faster when a fault is detected. 
     Still referring to  FIG. 7 , when shield integrity is compromised, such as, for example, a break in shields  513 ,  515 , or a voltage drop across areas of corrosion within the power cable, the bias-on voltage V BE  at the base of Q 1  is insufficient to keep Q 1  in its conductive state. (See  FIG. 11B .) The voltage at the base of Q 2  (Q 1 C) rises to Q 2 &#39;s bias-on voltage turning on Q 2 , sufficiently increasing current flow through solenoid  519  to energize solenoid  519  to disengage manual reset switch  518 . Thus, interrupting power from the AC line source to the load. It is understood and appreciated that the full wave bridge rectifier  712  enables the SIC to detect and disconnect the AC line source from the load when a fault is detected during the positive or negative cycle of an input AC waveform (not shown). In other words, the SIC detects and interrupt power between the AC line source and load within 1 ms or less for a 60 Hz AC source. 
     Referring also to  FIG. 8  is an alternate circuit diagram of the SIC block diagram shown in  FIG. 5 . The rectified unsmoothed DC signal at B is routed to the base of npn transistor Q 1  via R 2  biasing Q 1  into an on condition, which in turn, drops rectified unsmoothed DC signal at A across R 8 . Thus, the gate voltage at the gate of SCR 1  is insufficient to trigger SCR 1 . It is appreciated that the frequency of the rectified unsmoothed DC signal at the base of Q 1  is of a sufficient frequency to keep Q 1  in a mostly conductive state in normal operations thus inhibiting sufficient bias-on gate voltage at the gate of SCR 1 . In other words, for example, when the rectified unsmoothed DC voltage signal at the base of Q 1  drops below the Q 1  bias-on voltage, turning Q 1  off, the bias-on gate voltage at the gate of SCR 1  begins to rise. However, under normal conditions, before there is sufficient bias-on gate voltage at the gate of SCR 1 , Q 1  turns back on, again dropping the gate voltage at the gate of SCR 1  below sufficient bias-on voltage (see  FIG. 11A ). 
     When Q 1  V BE  voltage drops, i.e., due to fault such as, for example, a break in shields  513 ,  515 , or a voltage drop across areas of corrosion, the bias-on voltage at the base of Q 1  is insufficient to keep Q 1  in its conductive state during the positive voltage swing a A. The gate voltage at the gate of SCR 1  rises to SCR&#39;s gate bias-on voltage triggering SCR 1  (see  FIG. 11C ) which sufficiently increases current flow through solenoid  519  to energize solenoid  519  to disengage manual reset switch  518 . Thus, interrupting power from the AC line source to the load. 
     Referring also to  FIG. 9  there is shown an alternate detailed circuit  90  of the block diagram  50  shown in  FIG. 5 . LCDI circuit  90  includes line shield  513 , neutral shield  515 , switch  518 , power supply circuit  912 , leakage current detection circuit (LCDC)  917 , solenoid  519 , and shield integrity circuit (SIC)  914 . As is described in more detail herein, when manual reset switch  518  is set line voltage is connected to LOAD and to power supply circuit  912  via solenoid  519 . Power supply circuit  912  supplies bias voltages to LCDC  917 , SIC  914 , and shields  513  and  515 . As is discussed and shown in more detail herein, the SIC  914  allows a small amount of solenoid current to flow through solenoid  519  but less than the energizing current needed to energize solenoid  519  to disengage manual reset switch  518 . It is appreciated that not starting from zero energizing current allows solenoid  519  to energize faster when a fault is detected. 
     Still referring to  FIG. 9  and  FIGS. 12A-12B . When switch  518  is mechanically (manually) engaged AC line voltage is connect to LOAD. 60 Hz AC line voltage is also connected to power supply circuit  912  via solenoid  519 . Power supply circuit  912 , comprising half wave rectifier (diodes D 1 -D 2 ) outputs a half wave rectified unsmoothed DC signal at A. The rectified unsmoothed DC signal at A is routed through R 6  to LCDC  917  and SIC  914 , via shields  513  and  515  connected in series. 
     R 6  drops the amplitude of rectified unsmoothed DC signal at A to a predetermined amplitude at B. Voltage dividers R 3 /R 7  drops the amplitude of rectified unsmoothed DC signal at B to a predetermined amplitude at C. Under normal conditions, the voltage amplitude at C, the gate of SCR 2  LCDC switch  517 A, is insufficient to trigger SCR 2  into an on condition. It will be appreciated, however, that C 3  charges to a voltage determined by R 3 , R 7  to maintain a minimum voltage on the gate of SCR 2 . If an adverse leakage condition occurs, e.g., arcing from AC line voltage to either shield  513  or  515 , the gate voltage at C rises from the charge on C 3  to trigger SCR 2  into an on-condition. In the SCR 2  on, or conducting condition, current flow through solenoid  519  is increased to a solenoid energizing level to disengage manual reset switch  518  and interrupt power between AC line source and load. Again, it is appreciated that not starting from zero gate voltage allows SCR 2  to trigger faster when a fault is detected than if the gate voltage was starting from zero volts. 
     Still referring to  FIG. 9 , the half wave rectified unsmoothed DC signal at B is routed to the base of npn transistor Q 1 , via R 2  (see  FIG. 1A ), biasing Q into an on condition during the positive cycle of the rectified unsmoothed signal. When Q 1 (B) voltage drops below V BE  Q 1  turns off and the voltage at Q 1 (C), is near 0 v due to the unsmoothed signal at A dropping to near 0 v in the cycle. When the unsmoothed DC signal at A swings positive, Q 1  is again biased on, dropping the unsmoothed DC signal at A across R 8 , keeping Q 2  in an off condition during normal operation. 
     Still referring to  FIG. 9 , it is understood that under normal conditions the rectified unsmoothed signal at A is dropped across resistor R 8  and that R 8  is sized to allow an amount of AC current less than the SOL 1   519  energizing current to flow through R 8  through Q 1  back to neutral when Q 1  is conducting. During Q 1 &#39;s off state, or non-conducting state, SOL 1   519  inductively opposes the change in current until Q 1  again turns on, thus maintaining, or nearly maintaining the current flow through SOL 1   519 . It is understood and appreciated that the small amount of solenoid current flowing through solenoid SOL 1   519  is less than the energizing current needed to energize solenoid  519  to disengage manual reset switch  518 . It is further appreciated that not starting from zero energizing current allows solenoid  519  to energize faster when a fault is detected. 
     Still referring to  FIG. 9 , when shield integrity is compromised, such as, for example, a break in shields  513 ,  515 , or a voltage drop across areas of corrosion within the power cable, the bias-on voltage Vat at the base of Q 1  is insufficient to keep Q in its conductive state. (See  FIG. 12B .) The voltage at the base of Q 2  (Q 1 C) rises to Q 2 &#39;s bias-on voltage turning on Q 2 , sufficiently increasing current flow through solenoid  519  to energize solenoid  519  to disengage manual reset switch  518 . Thus, interrupting power from the AC line source to the load. 
     Referring also to  FIG. 10  is an alternate circuit diagram of the SIC block diagram shown in  FIG. 5 . The half wave rectified unsmoothed DC signal at B is routed to the base of npn transistor Q 1  via R 2  biasing Q into an on condition, which in turn, drops rectified unsmoothed DC signal at A across R 8 . Thus, the gate voltage at the gate of SCR 1  is insufficient to trigger SCR 1 . It is appreciated that the frequency of the half wave rectified unsmoothed DC signal at the base of Q 1  is of a sufficient frequency to keep Q 1  in a mostly conductive state in normal operations thus inhibiting sufficient bias-on gate voltage at the gate of SCR. In other words, for example, when the rectified unsmoothed DC voltage signal at the base of Q 1  drops below the Q 1  bias-on voltage, turning Q 1  off, the bias-on gate voltage at the gate of SCR 1  begins to rise. However, under normal conditions, before there is sufficient bias-on gate voltage at the gate of SCR 1 , Q 1  turns back on, again dropping the gate voltage at the gate of SCR 1  below sufficient bias-on voltage (see  FIG. 12A ). 
     When Q 1  V BE  voltage drops, i.e., due to fault such as, for example, a break in shields  513 ,  515 , or a voltage drop across areas of corrosion, the bias-on voltage at the base of Q 1  is insufficient to keep Q 1  in its conductive state during the positive voltage swing a A. The gate voltage at the gate of SCR 1  rises to SCR 1 &#39;s gate bias-on voltage triggering SCR 1  (see  FIG. 12C ) which sufficiently increases current flow through solenoid  519  to energize solenoid  519  to disengage manual reset switch  518 . Thus, interrupting power from the AC line source to the load. 
     Referring also to  FIG. 10A  there is shown an exploded partial view of a circuit connection of the return wire shown in  FIGS. 3B-E . Those skilled in the art will appreciate the alternate shield connections to circuits described earlier. 
     Referring also to  FIG. 13  there is shown a flow diagram illustration of a method for constructing a power cord for detecting and interrupting line voltage between an AC line end and a load end of the power cord in accordance with the present invention  1300 . 
     Step  1301  provides a unit length of an insulated conductive neutral wire. Step  1302  wraps the insulated neutral wire with a conductive wrapping having a conductive side and a non-conductive side, with the conductive side facing out. The conductive side of the wrapping may be any suitable conductive material such as, for example, aluminum foil. Step  1303  wraps a conductive flexible media around the wrapped neutral wire such that the flexible media is in electrical contact with the conductive side of the conductive wrap and covers 30% of the unit length of the wrapped neutral wire. The conductive flexible media may be any suitable conductive material such as a copper flexible media, or a conductive flexible media woven from conductive material such as, but not limited to, high-performance carbon fiber/gold/copper composite wire, conductive graphene wire, or conductive graphene yarn. 
     Step  1304  provides a unit length insulated conductive line wire and step  1305  provides a unit length tinned conductive wire. The tinned wire may be any suitable conductive wire such as a solid conductive wire or stranded conductive wire. Step  1306  wraps the tinned wire and the insulated conductive line wire with a line wire shield having a conductive and non-conductive side with the conductive side facing in and in electrical contact with the tinned wire. (See  FIGS. 3A-3B ) 
     Step  1307  connects the tinned wire to the conductive flexible media or neutral shield at the load end of the power cord. 
     Step  1308  provides a leakage current detection circuit (LCDC) for detecting leakage current from the conductive neutral wire or the conductive line wire and a shield integrity circuit (SIC) for monitoring the neutral wire shield or the line wire shield integrity. The LCDC and SIC may be any of the embodiments previously described. 
     Step  1309  connects the LCDC and SIC to the conductive flexible media at the line end of the neutral shield conductor. It is understood that the shields described herein are connected in series at the load end of the power cord. Step  1310  provides a power supply circuit for energizing the LCDC and SIC and also energizes the line wire shield at the line end of the line wire shield with a first voltage. 
     Step  1313  interrupts AC line voltage if the LCDC detects a voltage (e.g., an arcing condition) rising above the first voltage. 
     Step  1314  interrupts AC line voltage if the SIC detects the first voltage falling below a second predetermined level. (See  FIGS. 11A-12C ). 
     Referring also to  FIG. 13A  there is shown an illustration of a flow diagram of an alternate method for constructing a power cord for detecting and interrupting line voltage between an AC line end and a load end of the power cord in accordance with the present invention, step  1301 A. 
     Step  1302 A provides a unit length insulated conductive: neutral wire, line wire, return wire, and ground wire. Step  1303 A wraps the insulated conductive: neutral wire, line wire, return wire, and ground wires with a shield having a conductive side and a non-conductive side with the conductive side of the shield facing out. (See  FIGS. 3B-3C ) The conductive side of the wrapping may be any suitable conductive material such as, for example, aluminum foil. 
     Step  1304 A wraps a conductive flexible media around the shield such that the conductive flexible media is in electrical contact with the conductive side of the shield and the conductive flexible media covers 30% of the unit length. The conductive flexible media may be any suitable conductive material such as a copper flexible media, or a conductive flexible media woven from conductive material such as, but not limited to, high-performance carbon fiber/gold/copper composite wire, conductive graphene wire, or conductive graphene yarn. 
     Step  1305 A connects the return wire to the conductive flexible media and/or the shield at the load end of the power cord. 
     Steps  1306 A and  1307 A provides a leakage current detection circuit (LCDC) for detecting leakage current from the conductive neutral wire or the conductive line wire; and a shield integrity circuit (SIC) for monitoring the neutral wire shield or the line wire shield integrity. The LCDC and the SIC are connected to the return wire. The LCDC and SIC may be any of the embodiments previously described. 
     Step  1308 A provides a leakage current detection circuit (LCDC) for detecting leakage current from the conductive neutral wire or the conductive line wire and a shield integrity circuit (SIC) for monitoring the neutral wire shield or the line wire shield integrity. The LCDC and SIC may be any of the embodiments previously described. 
     Step  1309 A connects the LCDC and SIC to the conductive flexible media via the return wire. It is understood that the shields described herein are connected in series at the load end of the power cord. 
     Step  1310 A provides a power supply circuit for energizing the LCDC and SIC and also energizes the line wire shield at the line end of the line wire shield with a first voltage. 
     Step  1313 A interrupts AC line voltage if the LCDC detects a voltage (e.g., an arcing condition) rising above the first voltage. 
     Step  1314 A interrupts AC line voltage if the SIC detects the first voltage falling below a second predetermined level. (See  FIGS. 11A-12C ). 
     Referring also to  FIG. 13B  there is shown an illustration of a flow diagram of a second alternate method for constructing a power cord for detecting and interrupting line voltage between an AC line end and a load end of the power cord in accordance with the present invention, step  13 C 00 . 
     Step  13 C 01  provides a unit length insulated conductive neutral wire. Step  13 C 02  wraps the insulated conductive neutral wire with a neutral wire shield having a conductive side and a non-conductive side, with the conductive side facing out. Step  13 C 03  wraps a conductive flexible media around the neutral wire shield such that the conductive flexible media is in electrical contact with the conductive side of the neutral wire shield and the conductive flexible media covers 30% of the unit length. The conductive flexible media may be any suitable conductive material such as a copper flexible media, or a conductive flexible media woven from conductive material such as, but not limited to, high-performance carbon fiber/gold/copper composite wire, conductive graphene wire, or conductive graphene yarn. 
     Steps  13 C 04  through  13 C 06  provide a unit length insulated conductive line wire. The insulated conductive line wire is wrapped with a neutral wire shield having a conductive side and a non-conductive side, with the conductive side facing out. A conductive flexible media is wrapped around the line wire shield such that the conductive flexible media is in electrical contact with the conductive side of the line wire shield and the conductive flexible media covers 30% of the unit length. The conductive flexible media may be any suitable conductive material such as a copper flexible media, or a conductive flexible media woven from conductive material such as, but not limited to, high-performance carbon fiber/gold/copper composite wire, conductive graphene wire, or conductive graphene yarn. (See  FIGS. 3D-3E ) 
     Step  13 C 07  connects a return wire to the line wire shield and the neutral wire shield at the load end of the power cord. Steps  3 C 08  and  13 C 09  provide a leakage current detection circuit (LCDC) for detecting leakage current from the conductive neutral wire or the conductive line wire and a shield integrity circuit (SIC) for monitoring the neutral wire shield or the line wire shield integrity. The LCDC and SIC are connected to the return wire. 
     Step  13 C 10  provides a power supply circuit for energizing the LCDC and SIC and also energizes the line wire shield at the line end of the line wire shield with a first voltage. Step  13 C 13  interrupts AC line voltage if the LCDC detects a voltage (e.g., an arcing condition) rising above the first voltage. Step  13 C 14  interrupts AC line voltage if the SIC detects the first voltage falling below a second predetermined level. (See  FIGS. 11A-12C ). 
     It should be understood that the foregoing description is only illustrative of the invention. Thus, various alternatives and modifications can be devised by those skilled in the art without departing from the invention. For example, solid state devices SCR 1  or Q 2  can be any suitable solid-state device. Accordingly, the present invention is intended to embrace all such alternatives, modifications and variances that fall within the scope of the appended claims.