WO2015099776A1

WO2015099776A1 - Detection wiring for evse electrical cable insulation

Info

Publication number: WO2015099776A1
Application number: PCT/US2013/078055
Authority: WO
Inventors: Marcel MONTEMAYOR CAVAZOS; Gerardo RODRÍGUEZ NÁJERA; Eduardo HERREJON ALVARADO; Saúl LÓPEZ RANGEL; Víctor Daniel HERNÁNDEZ PLATA
Original assignee: Schneider Electric USA, Inc.
Priority date: 2013-12-27
Filing date: 2013-12-27
Publication date: 2015-07-02

Abstract

A detection wiring system and method provides advance detection of exposed, broken, or otherwise damaged electrical wiring insulation. The detection wiring system and method is particularly useful for cables that are routinely exposed to outdoor conditions, theft, or vandalism, such as EVSE cables. The system and method involve dedicated detection wiring placed within an electrical cable and monitored for electrical continuity. The detection wiring breaks before the internal conductors of the electrical cable break when the cable is subjected to stress or strain. If a break or disruption in the electrical continuity of the detection wiring is detected, an alarm is raised and/or a trip circuit actuated to alert an operator and/or cut off power to the cable. This helps proactively detect exposed, broken, or otherwise damaged electrical cables, thus minimizing potential electrical shock hazards and also deterring theft and/or vandalism.

Description

DETECTION WIRING FOR EVSE ELECTRICAL CABLE INSULATION

Inventors: Marcel Montemayor Cavazos, Gerardo Rodriguez Najera, Eduardo Herrejon

Alvarado, Saul Lopez Rangel, and Victor Daniel Hernandez Plata

FIELD OF THE INVENTION

[0001] The disclosed embodiments relate generally to a system and method for detecting exposed, broken, or otherwise damaged electrical wire insulation and, more particularly, to a system and method for proactively detecting such damaged insulation.

BACKGROUND OF THE INVENTION

[0002] Power cords, electrical cables, wires and the like are often subjected to mechanical stress and strain that can damage the outer layer of insulation on such power cords and cables. The mechanical stress and strain may result from the cable being bent, twisted, stretched, compressed, cut, heated, cooled, and the like. While a cable with damaged insulation may continue to function normally for a while, over time the damaged area weakens further until the integrity of the outer insulation is eventually compromised. Such compromised insulation not only degrades the performance of the cable over time, causing the cable eventually to fail, but could also lead to an electrical shock hazard.

[0003] The above problem is particularly common for electric vehicle supply equipment (EVSE) cables that are attached to charging stations used to charge electric vehicle. The rise in the number of electric vehicles being driven over the past few years has created a demand for more charging stations to recharge the batteries of such vehicles. As more people use them, it is not uncommon for EVSE cables attached to such charging stations to be run over or trapped underneath tires due to their close proximity to the vehicles. Public charging stations have an additional problem in that the EVSE cables are often exposed to outdoor conditions, including heat, rain, snow, ice, and the like, and are also frequent targets of theft or vandalism, any of which can lead to the cables being damaged.

[0004] Existing efforts to detect damage to or theft of power cords and electrical cables, including EVSE cables, have focused on detecting breaks or interruptions to the electrical conductors within the cables. But by the time the breaks or interruptions are detected, preventing the breaks is no longer a feasible option. At that point, there is little recourse other than to replace the power cord or electrical cable, which can be expensive both in terms of the replacement cost of the cords and cables themselves as well as the downtime resulting from the outage.

[0005] Thus, a need exists for an improved way of detecting exposed, broken, or otherwise damaged electrical cables and, more particularly, detecting such exposed, broken, or otherwise damaged cables in a proactive manner. SUMMARY OF THE INVENTION

[0006] The disclosed embodiments are directed to a system and method for advance detection of exposed, broken, or otherwise damaged electrical wiring insulation. The system and method disclosed herein has applicability to various types of electrical cables, and is particularly useful for cables that are routinely exposed to outdoor conditions, theft, or vandalism, such as EVSE cables. In general, the disclosed system and method involve dedicated detection wiring apart from the main conductors of the cable that is placed within an electrical cable and monitored for electrical continuity. The detection wiring is designed to break before, and preferably long before, the internal conductors of the electrical cable break when the cable is subjected to stress or strain. In general operation, if a disruption in the electrical continuity of the detection wiring is detected, an alarm is raised and/or a trip circuit actuated to alert an operator and/or cut off power to the cable. This helps proactively detect exposed, broken, or otherwise damaged electrical cables, thus minimizing potential electrical shock hazards and also deterring theft and/or vandalism.

[0007] In some embodiments, the detection wiring may be embedded within the electrical cable's outer layer of electrical insulation, or it may reside between cable's outer layer of insulation and its inner layer of electrical insulation. In either case, by virtue of its location, the detection wiring experiences mechanical stress or strain before the cable's internal electrical conductors experience the stress or strain. This causes the detection wiring to break before the internal conductors break. In some embodiments, a circuit interrupt detector may be connected to the detection wiring to monitor its electrical continuity. When the circuit interrupt detector detects a disruption in electrical continuity, it sends an appropriate signal to raise an alarm and/or actuate a trip circuit that cuts off the power to the cable.

[0008] In some embodiments, the detection wiring may be a spiral wire wrapped around the electrical cable's inner layer of the electrical insulation. Alternatively, in some embodiments, instead of a spiral wire, the detection wiring may be one or more substantially straight wires running parallel with the cable's internal electrical conductors and beneath or within the electrical cable's outer layer of electrical insulation. In either case, the detection wiring is preferably selected or designed so that it has a lower breaking point than the cable's internal conductors. In some embodiments, the detection wiring may also include a thermal fuse that is designed to break if the temperature of the cable exceeds the thermal fuse temperature.

[0009] In general, in one aspect, the disclosed embodiments are directed to a detection wiring system for an electrical cable having an outer insulation layer and an inner insulation layer. The system comprises a detection wire within the electrical cable, the detection wire located external to the inner insulation layer, and a circuit interrupt detector connected to the detection wire. The circuit interrupt detector is configured to detect when an electrical continuity of the detection wire has been disrupted and transmit an interrupt signal in response to the electrical continuity of the detection wire being disrupted.

[0010] In general, in another aspect, the disclosed embodiments are directed to a system for detecting damage to an electrical cable. The system comprises dedicated detection wiring disposed in an insulation of the electrical cable, the dedicated detection wiring configured to break before an internal conductor of the electrical cable breaks when the electrical cable experiences mechanical stress or strain. The system further comprises a circuit interrupt detector connected to the dedicated detection wiring, the circuit interrupt detector configured to detect when an electrical continuity of the dedicated detection wiring has been disrupted. The circuit interrupt detector is configured to transmit an interrupt signal in response to the electrical continuity of the dedicated detection wiring being disrupted.

[0011] In general, in yet another aspect, the disclosed embodiments are directed to a method of detecting damage to an electrical cable. The method comprises monitoring a dedicated detection wire in an insulation of the electrical cable, and detecting when the dedicated detection wire in the insulation of the electrical cable has been broken. The method further comprises transmitting an interrupt signal in response to the dedicated detection wire in the insulation of the electrical cable being broken. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The foregoing and other advantages of the disclosed embodiments will become apparent upon reading the following detailed description and upon reference to the drawings, wherein:

[0013] FIG. 1 illustrates an electric vehicle charging station and cable with detection wiring system according to some implementations of the disclosed embodiments;

[0014] FIG. 2 illustrates an exemplary detection wiring according to some implementations of the disclosed embodiments;

[0015] FIG. 3 illustrates an exemplary detection system according to some implementations of the disclosed embodiments;

[0016] FIGS. 4A-4B illustrate an exemplary detection wiring in the form of a spiral wire according to some implementations of the disclosed embodiments;

[0017] FIG. 5 illustrates an exemplary detection wiring in the form of a straight wire according to some implementations of the disclosed embodiments;

[0018] FIG. 6 illustrates an exemplary detection wiring including a thermal fuse according to some implementations of the disclosed embodiments;

[0019] FIG. 7 illustrates an exemplary detection wiring located between an outer insulation layer and an inner insulation layer according to some implementations of the disclosed embodiment; and

[0020] FIG. 8 illustrates an exemplary circuit interrupt detector for a detection wiring according to some implementations of the disclosed embodiments.

DETAILED DESCRIPTION OF THE DISCLOSED EMBODIMENTS

[0021] As an initial matter, it will be appreciated that the development of an actual, real commercial application incorporating aspects of the disclosed embodiments will require many implementation specific decisions to achieve the developer's ultimate goal for the commercial embodiment. Such implementation specific decisions may include, and likely are not limited to, compliance with system related, business related, government related and other constraints, which may vary by specific implementation, location and from time to time. While a developer's efforts might be complex and time consuming in an absolute sense, such efforts would nevertheless be a routine undertaking for those of skill in this art having the benefit of this disclosure.

[0022] It should also be understood that the embodiments disclosed and taught herein are susceptible to numerous and various modifications and alternative forms. Thus, the use of a singular term, such as, but not limited to, "a" and the like, is not intended as limiting of the number of items. Similarly, any relational terms, such as, but not limited to, "top," "bottom," "left," "right," "upper," "lower," "down," "up," "side," and the like, used in the written description are for clarity in specific reference to the drawings and are not intended to limit the scope of the invention.

[0023] Referring now to FIG. 1, an electrical vehicle charging station 10 is shown that is equipped with a detection wiring system (and method therefor) according to the disclosed embodiments. Note that although the charging station 10 is primarily discussed herein, the disclosed detection wiring system and method may have applicability for other types of electrical cables and is particularly useful for cables that are routinely exposed to outdoor conditions, theft, or vandalism.

[0024] As can be seen, the charging station 10 includes a housing 12 that houses the various components making up the charging station 10, one or more standard connectors 14 that connect the charging station 10 to an electric vehicle (not shown), and one or more EVSE cables 16 that carry current from the charging station 10 to the electric vehicle. In accordance with the disclosed embodiments, each EVSE cable 16 may include detection wiring, indicated generally at 2 in FIG. 1 and shown in more detail in FIG. 2, for detecting damage and/or theft to the EVSE cable 16. A detection system for the detection wiring, indicated generally at 3 in FIG. 1 and shown in more detail in FIG. 3, is provided in the housing 12 for detecting a break in the detection wiring and cutting off the current flowing through the EVSE cable 16 and, optionally, generating an alarm or other notification.

[0025] FIG. 2 shows a section of the EVSE cable 16 in more detail. In a typical arrangement, the EVSE cable 16 includes an outer electrical insulation layer 20, an inner electrical insulation layer 22, and several electrical conductors 24. Detection wiring 26 may then be disposed between the outer electrical insulation layer 20 and the inner electrical insulation layer 22. In some embodiments, the detection wiring 26 may be dedicated detection wiring in that it operates primarily or even exclusively to help detect damage and/or theft to the EVSE cable 16 and provides little or no additional benefit. In other embodiments, the detection wiring 26 may be a type of wiring that also reinforces or further strengthens the EVSE cable 16, or imparts additional other benefits to the cable.

[0026] In the embodiment of FIG. 2, the detection wiring 26 is a spiral wire wrapped around the EVSE cable's electrical conductors 24 and between the outer electrical insulation layer 20 and the inner electrical insulation layer 22 along the length of the EVSE cable 16. The spiral wire forms a number of loops or windings around the inner electrical insulation layer 22 that may vary according to the needs of the application. In particular, a larger number of loops may provide greater protection than a smaller number of loops, but may require more effort to apply. It is also possible to vary the distribution of the loops. For example, the loops may be evenly distributed along the EVSE cable 16 in some embodiments, or there may be more loops formed along the portion of the EVSE cable 16 that is more susceptible to stress and strain, such as the middle portion, relative to other portions.

[0027] In operation, when the EVSE cable 16 is subjected to stress or strain, the detection wiring 26 experiences the stress or strain before the electrical conductors 24, and is thus more likely to break before the electrical conductors 24 do. In preferred embodiments, the detection wiring 26 is made of a weaker material, or a thinner material, or both, compared to the electrical conductors 24. This helps ensure that the detection wiring 26 breaks before the electrical conductors 24 do when the EVSE cable 16 is subjected to stress or strain. Once the detection wiring 26 breaks, its electrical continuity is disrupted, and this disruption may be detected by the detection system shown in FIG. 3.

[0028] As can be seen in FIG. 3, in some embodiments, the detection system may include a circuit interrupt detector 28, a trip circuit 32, and an alarm 30, which may be optional. Other components may also be included with the detection system, such as a wireless transmitter and the like, without departing from the scope of the disclosed embodiments. Preferably, the circuit interrupt detector 28, alarm 30, and trip circuit 32 are located within the housing 12, as shown in FIG. 1. In some embodiments, however, instead of being located within the housing 12, the circuit interrupt detector 28, alarm 30, and trip circuit 32 may be located within the connector 14. In the latter arrangement, a separate detection system may be needed for the connector 14 of each EVSE cable 16 rather than a single detection system for both cables, as would be the case for the embodiment of FIG. 1.

[0029] In general, the circuit interrupt detector 28 is designed to monitor the electrical continuity of the detection wiring 26 and detect any intermittent or permanent disruption in the electrical continuity. When such a disruption is detected, the circuit interrupt detector 28 actuates the trip circuit 32 immediately to cut off current to the EVSE cable 16 and prevent any potential electrical shock hazard. In some embodiments, the circuit interrupt detector 28 may also send a signal to the alarm 30 to alert appropriate personnel (e.g., a homeowner, station manager, etc.) that a EVSE cable 16 has been damaged. The alarm 30 may be inaudible alarm, a visual alarm, or a combination of both. Although not expressly shown, it is also possible to send a wireless signal to notify the appropriate personnel of the damage to the EVSE cable 16.

[0030] A partial side view of the EVSE cable 16 is depicted in FIGS. 4A and 4B showing a cross-section of the outer electrical insulation layer 20. As shown in FIG. 4A, the detection wiring 26 is in the form of a spiral wire that is embedded within the outer electrical insulation layer 20. The circuit interrupt detector 28 is connected to the ends of the spiral wire using any suitable connection technique known to those having ordinary skill in the art to form a closed circuit. Then, if the detection wiring 26 breaks for any reason, intermittent or otherwise, the circuit interrupt detector 28 detects the disruption in the detection wiring's electrical continuity. Such a break is indicated generally at 34 in FIG. 4B. Although the stress or strain that causes the detection wiring 26 to break may not be sufficient to cause the outer electrical insulation layer 20 also to break, the breaking of the detection wiring 26 should nevertheless be detected and noted because the insulation layer has still undergone some damage. The circuit interrupt detector 28 thereafter actuates the trip circuit 32 to cut off power to the EVSE cable 16 and, optionally, sends a signal to the alarm 30 to alert the appropriate personnel of the break.

[0031] FIG. 5 illustrates another embodiment wherein the detection wiring is in the form of one or more substantially straight wires 36 instead of a spiral wire. As can be seen in this partial cross-section view, the one or more straight wires 36 is embedded in the outer electrical insulation layer 20 and runs parallel with the EVSE cable 16. The circuit interrupt detector 28 is then connected to the ends of the one or more straight wires to form a closed circuit. The number of straight wires 36 used may depend on the particular application, with more wires naturally providing greater protection. For example, a larger number of wires 36 may be needed for higher vehicle traffic areas relative to lower vehicle traffic areas to make the EVSE cable 16 more sensitive and hence more likely to detect damage that otherwise may not be detected if fewer wires 36 are used.

[0032] FIG. 6 illustrates another embodiment wherein the detection wiring 36 includes one or more thermal fuses 38. The one or more thermal fuses 38 are designed so that they break if the temperature of the cable exceeds a predefined temperature. This arrangement helps detect when the EVSE cable 16 is exposed to extreme heat, for example, from high internal current, vandalism, or both, that may potentially damage the cable. In the partial cross-section view shown here, the one or more thermal fuses 38 is used with the straight wire implementation 36. It is possible, of course, to use the one or more thermal fuses 38 with the spiral wire implementation 26 without departing from the scope of the disclosed embodiments.

[0033] FIG. 7 illustrates an embodiment of the EVSE cable 16 wherein the detection wiring is implemented as a spiral wire 40 disposed between the outer electrical insulation layer 20 and the inner electrical insulation layer 22. This embodiment is otherwise similar to the embodiments wherein the spiral wire is embedded within the outer electrical insulation layer 20, and may even be relatively easier to implement because the spiral wire 40 may be simply wrapped around the inner electrical insulation layer 22. The circuit interrupt detector 28 may then be connected to the spiral wire 40 in any suitable manner to form a closed circuit.

[0034] FIG. 8 illustrates an exemplary implementation of the circuit interrupt detector 28 according to some embodiments. Those having ordinary skill in the art will of course be able to devise numerous alternative implementations of the circuit interrupt detector 28 without departing from the scope of the disclosed embodiments. As can be seen, the circuit interrupt detector 28 may simply be a logic AND circuit that is connected to the detection wiring 26 to form a closed circuit. The electrical continuity of the closed- circuit maintains the inputs to the circuit at a logic high level, which maintains the output of the circuit at a logic high level. If the detection wiring 26 breaks in any way, intermittently or otherwise, the electrical continuity is broken, and the output of the circuit drops to a logic low level. Such a change in logic levels causes the trip circuit 32 to be actuated, shutting off the current to the EVSE cable 16 and, optionally, may also actuate the alarm 30.

[0035] In some embodiments, instead of discrete logic circuits, the circuit interrupt detector 28 may be in the form of an integrated processing unit. Such a processing unit may be any suitable processing unit known to those having ordinary skill in the art, including a microcontroller, a field programmable gate array (FPGA), an application- specific integrated circuit (ASIC), and the like. The processing unit may then be programmed with one or more modules or routines for detecting an interruption in the electrical continuity of the detection wiring 26 and outputting the appropriate interrupt signals to cut off current to the EVSE cable 16 and, optionally, actuate the alarm 30.

[0036] While particular aspects, implementations, and applications of the present disclosure have been illustrated and described, it is to be understood that the present disclosure is not limited to the precise construction and compositions disclosed herein and that various modifications, changes, and variations may be apparent from the foregoing descriptions without departing from the spirit and scope of the disclosed embodiments as defined in the appended claims.

Claims

CLAIMS What is claimed is:

1. A detection wiring system for an electrical cable having an outer insulation layer and an inner insulation layer, comprising:

a detection wire within the electrical cable, the detection wire located external to the inner insulation layer; and

a circuit interrupt detector connected to the detection wire, the circuit interrupt detector configured to detect when an electrical continuity of the detection wire has been disrupted;

wherein the circuit interrupt detector is configured to transmit an interrupt signal in response to the electrical continuity of the detection wire being disrupted.

2. The system of claim 1, wherein the detection wire is a spiral wire wound along a length of the electrical cable.

3. The system of claim 1, wherein the detection wire is a straight wire running along a length of the electrical cable.

4. The system of claim 1, further comprising a thermal fuse connected to the detection wire, the thermal fuse configured to break if a temperature of the electrical cable exceeds a predefined temperature.

5. The system of claim 1, wherein the detection wire is embedded within the outer insulation layer.

6. The system of claim 1, wherein the detection wire is disposed between the outer insulation layer and the inner insulation layer.

7. A system for detecting damage to an electrical cable, comprising:

dedicated detection wiring disposed in an insulation of the electrical cable, the dedicated detection wiring configured to break before an internal conductor of the electrical cable breaks when the electrical cable experiences mechanical stress or strain; and

a circuit interrupt detector connected to the dedicated detection wiring, the circuit interrupt detector configured to detect when an electrical continuity of the dedicated detection wiring has been disrupted;

wherein the circuit interrupt detector is configured to transmit an interrupt signal in response to the electrical continuity of the dedicated detection wiring being disrupted.

8. The system of claim 7, further comprising an alarm system configured to alert an operator, wherein the circuit interrupt detector transmits the interrupt signal to the alarm system to set off the alarm system.

9. The system of claim 7, further comprising a trip circuit configured to cut off power to the electrical cable, wherein the circuit interrupt detector transmits the interrupt signal to the trip circuit to actuate the trip circuit.

10. The system of claim 7, wherein the electrical cable is an electric vehicle supply equipment (EVSE) cable for an EVSE charging station.

11. A method of detecting damage to an electrical cable, comprising:

monitoring a dedicated detection wire in an insulation of the electrical cable; detecting when the dedicated detection wire in the insulation of the electrical cable has been broken; and

transmitting an interrupt signal in response to the dedicated detection wire in the insulation of the electrical cable being broken.

12. The method of claim 11, wherein detecting when the dedicated detection wire in the insulation of the electrical cable has been broken comprises detecting when the electrical continuity of the dedicated detection wire has been disrupted.

13. The method of claim 11, wherein transmitting the interrupt signal in response to the dedicated detection wire in the insulation of the electrical cable being broken comprises transmitting an alarm signal to an alarm system configured to alert an operator.

14. The method of claim 11, wherein transmitting the interrupt signal in response to the dedicated detection wire in the insulation of the electrical cable being broken comprises transmitting an interrupt signal to a trip circuit configured to cut off power to the electrical cable.