Patent Publication Number: US-9887498-B2

Title: Compact protection device for automotive cigar lighter and power outlet

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to electrical power outlets and cigar lighter outlets, and in particular, to electrical power outlets and cigar lighter outlets, receptacles or sockets for use in automotive applications. More particularly, the present invention is related to a compact protection device for automotive cigar lighter sockets and electrical power outlets and provides protection against overheating and over-current conditions. 
     The trend in automotive design is for increased use of electronic devices that require more power and draw higher currents from the power outlets or cigar lighter sockets in motor vehicles. 
     Two common issues result. One is over-current, that is, excessive current draw due to excessive power consumption or a short circuit in the plugged-in device. Another is overheating due to high current and often poor quality of after-market accessory plugs that cannot handle the currents drawn through them. 
     In the past, over-current protection has been provided by using a fuse that is installed in the vehicle fuse box. This fuse is accessible to the vehicle operator and often times, such vehicle operators are inexperienced, particularly with electrical matters and may replace a blown fuse with a fuse of the wrong type, for example, a higher current fuse which will no longer provide proper over-current protection, leading to excessive current draw which can damage the vehicle wiring and/or the accessory device and, in a worst case, cause a fire or injury. 
     Over-temperature or overheating protection has been provided in cigar lighters in automotive vehicles typically by providing a second bimetallic element, in addition to the bimetallic thermostatic element that disconnects the cigar lighter from the electrical current when it has been heated to ignition temperature. Typically, the additional bimetallic thermostatic element responds to excessive heating and short-circuits the power to the cigar lighter socket in the vehicle, which then blows the fuse provided in the vehicle fuse box. Such over-temperature protection for vehicle cigar lighters operates adequately when the heat build-up is fast but does not adequately operate for cigar lighters when they are used as power outlets in which the heat build-up is much slower. In such case, the additional bimetallic element will fail to provide short-circuit protection. 
     For power outlets in automotive vehicles that are not equipped as cigar lighter outlets, typically over-temperature protection has not been provided. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a compact over-current protection device for an automotive power outlet and/or automotive cigar lighter socket. According to the invention, the over-current protection device is located compactly within the power outlet/cigar lighter socket. 
     It is furthermore an object of the invention to provide an automotive power outlet/cigar lighter socket that provides effective over-temperature protection both in power outlets not equipped as cigar lighter outlets for electronic devices plugged into the outlets and for the sockets of cigar lighters. 
     The over-current protection is preferably implemented using a fast-action surface mount fuse mounted on a printed circuit board (PCB) which is integrated into the cigar lighter outlet or power outlet. This is believed to be unique since the other known available solutions for fuse mounting in or on the socket rely on a more conventional mechanical assembly. 
     The over-current protection according to the invention is compact in size and increases the overall length of the existing products by no more than a few millimeters and, in particular, by only about 1.6 millimeters or so. This is unique in terms of minimum impact to product size increase and maximizes compatibility with existing manufacturing processes when compared with other available solutions. 
     The surface mount fuse using surface mount technology (SMT) is small in size and enclosed in or adjacent to the connector housing at the back or distal end of the cigar lighter outlet or power outlet. Thus, the fuse itself is protected against damage or tampering, unlike other available solutions. In addition, since the surface mount fuse is enclosed and contained in or near the connector housing, when it blows, any effects due to arcing and melting are confined to that space. 
     The rating of the surface mount fuse in the outlet/socket is customizable by the manufacturer. The preferred rating is that the outlet integrated fuse does not blow during normal use. It only blows when the current exceeds its specified rating for the outlet and, when it does blow, it acts faster than the fuse in the vehicle fuse box does. Therefore, the over-current protection of the outlet is guaranteed and independent of the vehicle side fuse which can be tampered with or changed with an inappropriately sized fuse by an inexperienced user. 
     The over-temperature protection is preferably implemented using a spring biased electrically and heat conductive device, for example, a metal leaf spring, and a thermoplastic disc. The leaf spring is electrically and mechanically connected to the center electrical contact of the socket which is normally the positive side contact connected to the positive side of the vehicle DC electrical supply. The leaf spring preferably has two transverse contact legs spring loaded onto the thermoplastic disc that rests on the bottom of the metal socket which acts as the negative contact of the socket. In the event of overheating, the plastic disc softens and melts, acting as a thermal fuse. The leaf spring legs penetrate through the thickness of the thermoplastic disc and short-circuit to the metal socket. The short-circuiting further triggers over-current protection which can be provided by the outlet integrated fuse according to the invention or if not so provided, the vehicle side fuse (or other circuit interrupter, e.g., a circuit breaker) provided in the automotive fuse/circuit breaker box in the traditional case, depending on the manufacturer&#39;s preference. 
     The advantages of the outlet integrated fuse described above also apply in the case of over-temperature protection. That is, if the socket according to the invention is provided with the over-temperature protection, e.g., in the preferred embodiment, the leaf spring that short-circuits through the thermoplastic disc, and is also provided with the outlet integrated fuse, the short-circuiting of the leaf spring through the thermoplastic disc to the outlet/socket metal shell will then cause the integrated fuse to blow thereby providing the over-temperature protection. Since the outlet integrated fuse is provided in the negative return side of the socket/outlet, when the short-circuit is made by the leaf spring penetrating through the thermoplastic disc due to over-temperature, the short-circuit will cause the outlet integrated fuse also to blow. 
     The material of the thermoplastic disc is selected such that its melting point is above normal use maximum environmental temperatures and below the maximum protection temperature that is required. The leaf spring should be designed such that it adequately makes contact with the metal socket when the thermoplastic disc is penetrated after softening and melting to cause a short-circuit. The metal leaf spring and thermoplastic disc are contained inside the metal shell of the socket/outlet. The leaf spring should be positioned to be close to the top of the center rivet and mechanically and electrically in contact with the center rivet and insulated from the socket shell. The heat conduction from the heat source, i.e., the accessory plug, to the leaf spring is faster and more effective than any other available solutions that rely on a thermal fuse located typically at the back side of the socket which is away from the heat source. In contrast to these available solutions, because the leaf spring is located inside the socket and close to the heat source, the over-temperature protection is faster than these prior art designs. A significant drawback of the prior art designs is that the thermal fuse, because it is located at the rear of the socket, is not near the heat source. 
     According to one aspect, the invention comprises an electrical outlet comprising an electrically conductive socket well for slidably receiving an electrical plug, the well having a transverse distal end having a center hole; an insulating connector housing adjacent the transverse end of the socket well having at least two electrical terminals for connection to an electrical supply; a first of the electrical terminals being coupled to a central fastener and a second of the electrical terminals terminating in an electrically conductive element adjacent the transverse distal end of the socket well; a fuse member being provided between the transverse distal end of the socket well and the conductive element, the fuse member in series electrical connection between the conductive element and the socket well, the fuse member providing an electrical conduction path between the second electrical terminal and the socket well, further comprising an insulator disposed at the distal end of the socket well in the socket well, the central fastener holding the socket well, the insulator, the fuse member, insulating connector housing and first and second electrical terminals together as a unit; a proximal end of the central fastener providing a first electrical contact insulated from said socket well and the socket well providing a second electrical contact for electrically contacting with respective contacts of the electrical plug received in the socket well; the fuse member providing integral over-current protection for the electrical outlet. 
     In a preferred embodiment, the fuse member comprises an insulating member having first and second electrically conductive sides and a fuse element in series connection with the first and second electrically conductive sides, the first and second electrically conductive sides being in respective electrical contact with the socket wall and the conductive element, the conductive element comprising a planar conductive element. 
     Preferably the insulating member is a printed circuit board (PCB) and the fuse element is surface mount technology (SMT). 
     In a preferred embodiment, the electrical outlet also employs integral over-temperature protection. 
     According to another aspect, the invention comprises an electrical outlet comprising a conductive socket well for slidably receiving an electrical plug, the well having a transverse distal end having a center hole; an insulating connector housing adjacent the transverse end of the socket well having at least two electrical terminals for connection to an electrical supply; a first of said electrical terminals being coupled to a central fastener and a second of said electrical terminals in electrical contact with the socket well; further comprising an insulator disposed at the distal end of the socket well in the socket well, the central fastener holding the socket well, the insulator, the insulating connector housing and first and second electrical terminals together as a unit; a proximal end of the central fastener providing a first electrical contact insulated from said socket well and the socket well providing a second electrical contact for electrically contacting with respective contacts of the electrical plug received in the socket well; further comprising a thermoplastic insulating disc at the distal end of the socket well mounted between the insulator in the socket well and the transverse distal end of the socket well and being held in place by the central fastener disposed through a central hole of the thermoplastic insulating disc, further comprising a spring-loaded member electrically and mechanically connected to the central fastener and held in place in the insulator by the central fastener, the spring-loaded member biased against the thermoplastic insulating disc, the thermoplastic insulating disc having a melting point above a normal temperature range of use of the electrical outlet but below a threshold maximum temperature, whereby the thermoplastic insulating disc will soften at the maximum temperature and the spring-loaded member biased against the thermoplastic insulating disc will form an electrically conductive path through the thermoplastic insulating disc and electrically engage the transverse distal end of the socket well thereby short circuiting the electrical supply and causing circuit interruption to provide over-temperature protection. 
     In a preferred embodiment, the spring-loaded member comprises a leaf spring having first and second transverse arms and right angle ends directed to the thermoplastic disc for penetrating through the thermoplastic disc when the disc softens at the threshold maximum temperature, the right angle ends having contact points for electrically engaging with the transverse distal end of the socket well when the thermoplastic disc softens, further wherein the leaf spring has a center hole for electrical and mechanical engagement by the central fastener. 
     In a further preferred embodiment, the electrical outlet also employs integral over-current protection and the circuit interruption is by an integral fuse member. 
     Other objects, features and advantages of the present invention will be apparent from the detailed description which follows. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING(S) 
       The invention will be described in greater detail in the following detailed description with reference to the drawings in which: 
         FIG. 1  shows a cross-sectional view of a cigar lighter socket that implements the present invention. The present invention can also be employed, as described above, in an electrical power outlet not equipped as a cigar lighter outlet, which will have a similar design but which will not include certain elements used in a cigar lighter outlet, namely, the heat shield and the bimetal thermostat; 
         FIG. 2  shows an exploded perspective view of a cigar lighter outlet employing the present invention which is also applicable to an electrical power outlet which would be similar except eliminates components that are typically only used in a cigar lighter outlet, i.e., the heat shield and the bimetal thermostat; 
         FIG. 2A  shows a cross-section through the printed circuit board (PCB) that includes the socket/outlet integrated fuse, here shown as a surface mount technology (SMT) fuse; 
         FIG. 2B  shows a schematic diagram of the electrical wiring of the socket showing the over-temperature protection provided by the leaf spring and thermoplastic disc as well as the series connected over-current protection integrated fuse located on the printed circuit board; 
         FIG. 3  shows a perspective view of the socket/outlet; 
         FIG. 4  shows the heat shield which is used typically only in the lighter socket embodiment; 
         FIG. 5  shows the socket metal shell; 
         FIG. 6  shows the insulated electrical connector housing provided at the rear of the socket/outlet; 
         FIG. 7  shows one of the electrical terminals, typically the negative-side terminal; 
         FIG. 8  shows the other electrical terminal, typically the positive-side terminal; 
         FIG. 9  is a perspective view showing in greater detail the printed circuit board; 
         FIG. 9A  is a perspective view showing the other side of the printed circuit board showing the fuse; 
         FIG. 10  shows the bimetal thermostat that is used in the lighter socket embodiment but not employed in a non-lighter socket power outlet; 
         FIG. 11  shows a metal spacer/washer that is used between the over-temperature protection device, that is, the metal leaf spring, and the bimetal thermostat of  FIG. 10 , if so provided; 
         FIG. 12  shows the thermoplastic disc against which the over-temperature protection leaf spring rests in spring biased engagement; 
         FIG. 13  shows the thermal insulator upon which the metal leaf spring rests and which electrically isolates the leaf spring and bimetal thermostat in the lighter socket embodiment from the metal socket; 
         FIG. 14  shows the over-temperature protection leaf spring that is mounted in a channel of the thermal insulator; and 
         FIG. 15  shows the center fastener rivet that is received in the positive-side electrical terminal and, in particular, an eyelet of the positive-side terminal and is riveted to the positive-side terminal to secure all the elements of the socket/outlet together and provides an electrical contact surface for the spring-loaded positive-side terminal of a received electrical plug. 
     
    
    
     Other objects, features and advantages of the present invention will be apparent from the detailed description which follows. 
     DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION 
     Turning now to  FIG. 1 , this figure shows a cross-section through the outlet/socket/receptacle of the present invention.  FIG. 1  shows the over-temperature/over-current protection features of the present invention employed in a cigar lighter socket but an electric power outlet that is not normally employed as a cigar lighter socket would be essentially the same but would typically eliminate two elements, the heat shield and the bimetal thermostat, as described below. 
     The socket/outlet with over-current and over-temperature protection according to the present invention includes a socket shell  1  that is made of an electrically conductive material, typically steel plated with a rust resistant surface, but any electrically conductive metal that provides adequate temperature safeguards, particularly in the case of a cigar lighter socket, can be employed. Reference is also made to  FIG. 2  which shows an exploded view of the outlet/socket/receptacle. 
     The metal socket  1  is typically connected to the vehicle&#39;s negative-side electrical supply. The metal socket may be surrounded by a heat shield  2 , in the case of a cigar lighter socket. The heat shield is typically also made of metal, plated for rust resistance, and is typically also in electrical engagement with the metal socket and thus also connected to the negative-side of the vehicle electrical supply. 
     Mounted centrally within the metal socket  1  is an internal insulator  3 , typically a heat resistant or refractory insulator in the case of a cigar lighter socket. The insulator  3  has a center hole through which a center fastener, e.g., a rivet  9 , passes. The center rivet  9  also passes through all other components of the outlet/socket and is insulated by the internal insulator  3  from the metal socket and the heat shield but is in electrical engagement with a metal leaf spring  6  to be described in greater detail herein, a metal spacer  5  and a bimetal thermostat  4  that is used in the cigar lighter socket embodiment. In addition, the center rivet  9  passes through but is not electrically connected to the negative-side terminal  12  which has a terminal prong  12 A that passes through an opening in an insulating connector housing  11 . Mounted to the connector housing  11  and insulated from the negative terminal  12  is a positive-side terminal  13  that has an eyelet  13 A. The eyelet  13 A receives the distal end of the center rivet  9  and the center rivet  9  is riveted through the eyelet of the positive-side terminal  13  to secure all components of the outlet/socket together. 
     The invention provides novel over-current and/or over-temperature protection. 
     In order to provide over-current protection, a fuse member, preferably a printed circuit board (PCB)  8  with integral fuse is disposed between the negative-side terminal  12  and the distal or bottom end of the heat shield, in the case of a cigar lighter socket embodiment, if so provided, or the metal socket  1 . If the socket/outlet is not provided with the capability to supply a cigar lighter, then the printed circuit board  8  is disposed between the negative-side terminal  12  and the distal end of the metal socket  1 . 
     As shown in  FIG. 2A , the printed circuit board  8  comprises an insulating printed circuit board that includes conductive traces  8 B and  8 C on respective surfaces of the printed circuit board. In addition, an electrically conductive via  8 A is provided connecting one surface trace  8 B to the fuse  8 D which is connected then to the surface trace  8 C on the other side of the PCB. Thus, the fuse  8 D is connected in the negative return of the outlet/socket. Preferably the fuse is surface mount technology (SMT). The fuse is preferably selected as a fast-action fuse that will blow faster than the fuse in the vehicle fuse box when there is an over-current. 
     In addition, as will be explained below, when there is an over-temperature condition and the novel over-temperature protection device of the invention operates to short circuit the socket/outlet, the fuse  8 D, because it is connected in the negative return supply of the outlet/socket, will also blow providing the over-temperature protection. Thus, assuming fuse  8 D operates more quickly than the fuse in the vehicle fuse box, the over-temperature protection is provided by the combination of the over-temperature protection device provided in the socket according to the present invention causing the integrated fuse  8 D to blow. However, it is not necessary to provide both the over-temperature protection device and the over-current protection device according to the invention in the same outlet. Only one protection device can be used depending on the design specification. For example, only the fuse according to the invention may be employed thus providing only over-current protection. Alternatively, only the over-temperature protection device may be employed, in which case the on-board vehicle fuse is used to provide the over-temperature protection when the socket over-temperature protection device according to the invention operates. 
     The over-temperature protection is preferably provided by a metal leaf spring  6  which is mounted in insulated fashion in a channel of the internal insulator  3  above a thermoplastic disc  7  in the metal socket  1 . As shown in  FIG. 1 , the leaf spring  6  is provided with internal spring bias so that its tips  6 A ( FIG. 14 ) are biased against the thermoplastic disc  7 . The thermoplastic disc is preferably made of a plastic that does not soften at normal environmental temperatures but only begins to soften at a temperature somewhat below the maximum temperature to be protected against. The disc may comprise POM (acetal) which has a melting point around 170° C. When the socket approaches over-temperature conditions, the tips  6 A of the leaf spring, which may be of reduced surface area compared to the thickness of the metal of the leaf spring, i.e., the tips  6 A may be made somewhat pointed or sharpened in order to penetrate the thermoplastic, will penetrate through the thermoplastic disc and electrically engage with the bottom of the metal socket well  1  which is connected to the negative side of the vehicle electrical supply. Since the leaf spring  6  is connected to the positive side of the electrical supply by the center rivet  9  and positive terminal  13 , the vehicle electrical supply is short-circuited, causing the fuse  8 D on the printed circuit board to blow (or the on board vehicle fuse to blow if fuse  8 D is not provided), thereby providing over-temperature protection. A suitable temperature range at which the over-temperature protection operates is about 170° C.-180° C. 
     This is shown in schematic form by the electrical diagram in  FIG. 2B . 
     In  FIG. 2 , thermoplastic disc  7  is shown enlarged somewhat from the scale of the metal socket  1 . The thermoplastic disc  7  has an outside diameter such that it can be located at the bottom of the metal socket and has an outside diameter that provides a clearance fit in the inside diameter of the metal socket. 
     The printed circuit board  8  that contains the SMT fuse  8 D is disposed below the heat shield in a cigar lighter socket embodiment if the heat shield is employed or below the metal socket  1  if the socket is not a cigar lighter socket or does not have a heat shield. 
     On the other side of the printed circuit board  8 , the negative terminal  12  is disposed. The negative terminal  12  has a disc-like planar portion  12 C and a terminal end  12 A. The planar portion  12 C is electrically in contact with one of the traces on the printed circuit board. In particular, it is in contact with the trace  8 C on the printed circuit board  8  and thus in series electrical connection with the SMT fuse  8 D. The SMT fuse is in series connection with an electrical via  8 A which in turn is connected to the electrical trace  8 B on the other side of the PCB. 
     The electrical trace  8 C in the embodiment shown is in electrical contact with the negative-side terminal  12  and the electrical trace  8 B is in electrical contact with the heat shield  2 , if provided, or the metal socket  1 . The fuse  8 D is thus in series relationship with the metal socket and the negative-side terminal  12  and in the return side of the vehicle electrical supply. 
     In the case of an over-current condition, with or without an over-temperature condition, the fuse  8 D will blow. The fuse is selected to provide faster action than the fuse in the vehicle fuse box and is sized such that it provides for a maximum current carrying capacity. 
     In the event of an over-temperature condition, as explained above, the metal leaf spring will provide a short-circuit by penetrating through the softened thermoplastic disc  7  thus causing the short-circuit which will then cause an over-current condition, blowing the fuse  8 D, if so provided, or the vehicle on-board fuse. 
     Thus, the present invention provides both for over-current protection as well as over-temperature protection, in the preferred embodiment. However, it should be apparent to those of skill in the art that both means of protection need not be employed, depending on the specification. For example, the invention can be provided with only the over-current protection fuse mechanism and not the over-temperature protection mechanism which is provided by the metal leaf spring  6  and the thermoplastic disc  7 . Such an embodiment employing only the over-current fuse protection may be especially applicable to cigar lighter sockets which typically already employ over-temperature protection in the form of bimetal thermostats that are adapted to short circuit the outlet in the event of an over-temperature condition that is higher than the normal temperatures achieved in electrical cigar lighter outlets when the cigar lighter reaches ignition temperature. 
     Conversely, it may be desirable in certain situations only to provide for the over-temperature protection mechanism, that is, the metal leaf spring  6  and thermoplastic disc  7  of the preferred embodiment, and not provide the integrated fuse and merely rely on the vehicle fuse box fuse to provide the over-temperature protection when the leaf spring  6  short circuits through the thermoplastic disc  7  to the metal socket  1  in the case of the over-temperature condition. 
     However, the preferred embodiment of the present invention provides the integral over-current protection fuse as well as integral over-temperature protection as described. This is particularly suited for use in an electrical power outlet which is not used as a cigar lighter receptacle because the present invention provides a relatively fast acting over-temperature protection mechanism through the combination of the over-temperature protection leaf spring  6  and thermoplastic disc  7  and integrated fuse  8 D. 
       FIG. 3  shows the assembled electrical power outlet/cigar lighter socket showing the metal socket shell  1 , the external heat shield  2  and the insulating electrical terminal connector  11 . 
       FIG. 4  shows the heat shield  2 , which may be employed in the lighter socket embodiment.  FIG. 5  shows the metal socket  1  in more detail. The metal socket  1  includes inwardly biased lances  1 A which are adapted to hold the cigar lighter or accessory plug in mechanical engagement in the socket so that the plug or lighter does not fall out of the socket and is effectively held in the socket. These lances also provide for more positive electrical contact with the negative-side of the inserted lighter. Typically, the negative-side contact with an inserted electrical accessory plug is provided by spring loaded contacts on the known accessory plug that engage with the inner wall of the socket  1 . 
     In addition, openings  1 B on opposite sides of the socket shell  1  are provided opposite the clips  4 A of the bimetal thermostat  4  to provide for radial movement of the thermostat clips  4 A when the clips expand due to heating action to release the lighter. In the case of an electrical power outlet that is not capable of energizing a lighter, the openings  1 B can be eliminated. 
       FIG. 6  shows the electrical connector housing insulator  11 . 
       FIG. 7  shows the negative-side terminal  12 . In particular, the terminal end  12 A is received in an opening  11 A of the insulator  11  and a projection  11 B on the insulator  11  is adapted to position the negative terminal  12  by being received through an opening  12 B in the terminal  12 . The terminal  12  has the planar disc-like portion  12 C, as previously described for contacting the PCB  8  having the fuse element  8 D. 
     The terminal end  12 A is connected typically to the negative-side vehicle electrical supply. 
       FIG. 8  shows the positive-side terminal  13 . The eyelet  13 A is adapted to be received through the center opening  11 C in the insulator  11  and receives the center rivet  9 . Terminal end  13 B is connected typically to the positive-side of the vehicle electrical supply. 
       FIGS. 9 and 9A  show the PCB that contains the fuse  8 D. The PCB  8  includes a trace  8 B on one side and a trace  8 C on the other side. The trace  8 B is electrically connected through an electrically conductive via  8 A not visible in  FIGS. 9 and 9A  to the fuse  8 D which in turn is electrically connected to the electrical trace  8 C. The trace  8 C is in electrical contact with the negative-side electrical terminal  12 . The trace  8 B is in electrical contact with the socket well  1  and/or heat shield  2  if provided. 
       FIG. 10  shows the bimetal thermostat  4  provided if the socket is a cigar lighter receptacle. 
       FIG. 11  shows a metal spacer  5  that is provided between the over-temperature protection leaf spring  6  and the bimetal thermostat  4  in the preferred embodiment. The spacer  5  is provided to prevent interference between the leaf spring  6  and the bimetal thermostat and to facilitate electrical/thermal connection between the two parts. The spacer can be eliminated, and furthermore, may not be necessary in a non-lighter socket embodiment. 
       FIG. 12  shows the thermoplastic disc  7  that is located at the bottom of the socket well  1  and on which the thermal protection leaf spring  6  impinges. 
       FIG. 13  shows the internal insulator  3  provided with a channel  3 A for the leaf spring  6  and thermostat  4 , if so provided. 
       FIG. 14  shows the leaf spring  6  which rests in the channel  3 A of the internal insulator  3 . 
     Finally,  FIG. 15  shows the center fastener, e.g., rivet  9 , which is employed to hold all elements of the socket/outlet together. It also is connected to the positive-side of the vehicle electrical supply and its head  9 A is employed to provide electrical contact to a spring-loaded contact of an electrical accessory plug of an electrical/electronic device that is plugged into the outlet. 
     When the integrated fuse  8 D blows or the thermal protection device  6 / 7  operates, the electrical outlet is replaced with a new one. 
     Although the present invention has been described in relation to particular embodiments thereof, many other variations and modifications and other uses will become apparent to those skilled in the art. It is preferred, therefore, that the present invention be limited not by the specific disclosure herein, but only by the appended claims.