FIELD OF THE INVENTION

The present invention relates to surge protective devices (SPDs), in particular surge protective devices combined with a conventional electrical plug sockets.

BACKGROUND OF THE INVENTION

Surge Protective Device (SPD) and transient voltage surge suppressor (TVSS) are used to describe electrical devices typically installed in power distribution panels, process control systems, communications systems, and other heavy-duty industrial systems, for the purpose of protecting against electrical surges and spikes, including those caused by lightning. Scaled-down versions of these devices are sometimes installed in residential service entrance electrical panels, to protect equipment in a household from similar hazards. A voltage spike is a transient event, typically lasting tens of microseconds that may reach over 1,000 volts. Spikes can degrade wiring insulation and destroy electronic devices. A long term surge, lasting seconds, minutes, or hours, can destroy the surge protectors in an entire building or area. Even tens of milliseconds can be longer than a protector can handle.

A transient surge protector attempts to limit the voltage supplied to an electric device by either blocking or shorting current to reduce the voltage below a safe threshold. Blocking is done by using inductors which inhibit a sudden change in current. Shorting is done for example by spark gaps, discharge tubes, zener-type semiconductors, and MOVs (Metal Oxide Varistors), all of which begin to conduct current once a certain voltage threshold is reached, or by capacitors which inhibit a sudden change in voltage. Some surge protectors use multiple elements.

The most common and effective way is the shorting method in which the electrical lines are temporarily shorted together until the voltage is reduced by the resistance in the power lines. The spike's energy is dissipated in the power lines (and/or the ground), converted to heat. Since a spike lasts only 10s of microseconds, the temperature rise is minimal. However, if the spike is large enough, like a nearby hit by lightning, there might not be enough power line or ground resistance and the surge protection element can be destroyed and power lines melted.

Surge protectors for homes can be in power strips used inside, or a device outside at the power panel.

An electrical plug socket combined with an overvoltage protection device is addressed for example in DE3806478 and US5, 384,428.

DE3806478 discloses a plug socket for installation in buildings, whose base is combined with an overvoltage protection device, there being electrical connections between the overvoltage protection device and the conductors or connecting contacts of the plug-socket base. In order to reduce the production costs and at the same time the installation depth of such a plug socket with overvoltage protection, while maintaining the overvoltage protection, it is provided that the overvoltage protection device is installed in the base of the plug socket.

US5, 384,428 describes a receptacle wall plate having built-in circuitry for protecting electrical devices. The wall plate has a face plate for receiving at least one plug of an electrical device, and an inner surface and rounded edges which extend toward the wall to form a hollow body. When a plug is inserted through the face plate, an electrical circuit mounted in the hollow body automatically connects to the plug and protects the electrical devices from surges or other dangerous electrical conditions. In addition, electricity is automatically supplied to the electrical circuit when the plug is inserted through the face plate.

One object of the present invention is to provide a surge protector installed in a conventional wall outlet box located in a receptacle wall of a building.

Another object of the present invention is to provide SPD with a base unit and a replaceable unit where only the replaceable unit can damaged when protecting against electrical surges and spikes events. After the occurrence of such events where the replaceable unit is damaged, the user can replace the old damaged replaceable unit with a new replaceable unit and the SPD will be ready for use.

Yet another object of the present invention is to provide an SPD replaceable unit which is easy to replace and connect to the SPD base unit without the need for removing the base unit or the need of using an authorized electrician for the replacement.

Yet another object of the present invention is to provide an SPD which can be more resilient to electrical surges and spikes.

SUMMARY OF THE INVENTION

The present invention relates to surge protective devices (SPDs), in particular surge protective devices combined with a conventional electrical plug sockets.

In accordance with an embodiment of the present invention there is provided a Surge Protective Device (SPD) including, a replaceable unit having surge protective circuitry for detecting over voltage disturbances and protecting one or more protected sockets from said over voltage disturbances. The SPD further includes a base unit having one or more electrically operated switches such as but not limited to a relay. The base unit further includes one or more AC line delay circuitry for delaying the connection of the one or more AC lines to the one or more protected sockets. When the surge protective circuitry detects over voltage disturbances the one or more electrically operated switches is activated for disconnecting one or more AC lines from the one or more protected sockets thereby, creating open circuitry and preventing the transfer of electric power to the one or more protected sockets for a predetermine delay time. After the delay time ends the one or more AC line is reconnected to the one or more protected sockets by the one or more electrically operated switches to enable the electric power that travels through the AC line to pass to the one or more protected outlet. BRIEF DESCRIPTION OF THE DRAWINGS

The invention may be understood upon reading of the following detailed description of non-limiting exemplary embodiments thereof, with reference to the following drawings, in which:

Fig. 1A is a perspective view of an SPD in accordance with a preferred embodiment of the present invention where the SPD having a removable unit and a base unit. The SPD is connected to a conventional electric socket in a conventional electrical box;

Fig. IB is a perspective rear view of the SPD in accordance with a preferred embodiment of the present invention where the SPD is connected to a conventional electric socket;

Fig. 2 is a perspective front view of the SPD in accordance with one embodiment of the present invention;

Fig. 3A is a perspective view of the base unit in accordance with one embodiment of the present invention;

Fig. 3B is a perspective rear view of the replacement unit in accordance with one embodiment of the present invention;

Fig. 4 is a schematic block diagram illustrating the electrical connections between the SPD, conventional AC line and a conventional socket;

Fig. 5A is a perspective upper view of the base unit electric circuit card in accordance with one embodiment of the present invention;

Fig. 5B is a perspective view of the base unit electric circuit card in accordance with one embodiment of the present invention;

Fig. 5C is a perspective view of the replacement unit electric circuit card in accordance with one embodiment of the present invention;

Fig. 6A is an exemplary electric circuit of the replacement unit circuitry in accordance with some embodiments of the present invention; and Fig. 6B is an exemplary electric circuit of the base unit circuitry in accordance with some embodiments of the present invention.

The following detailed description of the invention refers to the accompanying drawings referred to above. Dimensions of components and features shown in the figures are chosen for convenience or clarity of presentation and are not necessarily shown to scale. Wherever possible, the same reference numbers will be used throughout the drawings and the following description to refer to the same and like parts.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

Referring first to Fig. 1A, there is shown a conventional electrical surge and spikes protected socket 20 such as but not limited to protected sockets, housed within a conventional electric box 22. The protected socket 20 includes receptacle contacts 24, which are engaged by the prongs of the plug of an electrical device (electrical load), not shown. The protected socket 20 is typically supported by a socket frame support 19. The electric box 22 is typically disposed in a wall of a building structure. The SPD of the invention 30 includes a base unit 32 and a replaceable unit 34 where the replaceable unit 34 is connectable to the base unit 32. The replaceable unit 34 is removable and is replaced whenever the replaceable unit 34 is damaged for example, caused by electrical surges and/or spikes. In accordance with the present invention the replacement unit 34 can be replaced when damaged. The replacement is done by simply disconnecting the connector 43 of replaceable unit 34 from the connector 41 of base unit 32 of the invention by manually replacing the removed replaceable unit 34 with a new or an undamaged replaceable unit 34. Base unit further includes a suitable quick release mechanism means 33 for connecting base unit 30 to any conventional frame support 19. It should be noted that quick release mechanism means 33 may vary depending on the outlet manufacturer: each outlet manufacturer has its own fastener for mounting sockets on the frame support 19. Preferably, the dimensions of the SPD are standard dimensions, which mean that, the SPD 30 can fit with any geometry of standard protected socket 20 and any standard electric box 22. The replaceable unit 34 further includes LEDs indicators 70 and 68 for example to indicate about the SPD 30 current mode of operation: "delay mode", "damaged mode" and "line active mode". Any other indicators can be used to notify the user about the current mode of operation for example and without limitation, using audio indicators, using an application installed in a remote device (such as but not limited to smart phone, PCs and etc.) that receives the information about the SPD 30 mode of operation through a wireless communication. The base unit 32 or the replacement unit 34 may include a controller with a memory and a wireless communication module, not shown, for enabling sending data about the current SPD mode of operation.

Referring to Fig. IB and also to Figs 5A , 5B, base unit 32 includes base unit circuit board 37 and replaceable unit 34 includes replacement unit circuit board 39. Base unit circuit board 37 includes three AC lines connectors, "L_IN " 36, "N_IN " 38 and "PE", 40 for connecting the building electrical wiring to the SPD. The connectors 36, 38 and 40 are connected respectively to the "line" conductive wire 36A, the "neutral" conductive wire 38A and the "protective earth (PE)" conductive wire 40A of the building electrical wiring which refers to also as AC lines. Base unit circuit board 37 further includes "L_OUT" connector 42 where a "Line out" AC wire 42A, is connected to the " L_OUT " connector. "Line out" AC wire will be live only when mains supply is not overvoltage interrupted for a minimum of predetermine time determined by a delay circuitry. Base unit circuit board 37 further includes interface connectors 41 to interface with the corresponding interface connectors 43 fitted on the replacement unit circuit board 39 side. The interface connectors 41 and interface connectors 43 passes the AC signals that comes from the following lines: the "line", "neutral", "protective earth (PE)", LED lines. The interface connectors further pass the signal that indicates about the replacement unit status (will be describe later in more detail). Referring also to Fig.4 there is shown a schematic block diagram illustrating the electrical wiring connection between the SPD of the invention 30, building AC line 31 and a conventional protected socket 20. Wire "Line", 36A that comes from the building AC line 31 is connected by connector 36 to base unit circuit board 37. Wire "Neutral", 38A that comes from the building AC line 31 is connected by connector 38 to base unit circuit board 37. And also is connected to the protected socket 20. Wire "PE", 40A that comes from the building AC line 31 is connected by connector 40 to base unit circuit board 37. "Line out" AC wire 42A comes from base unit circuit board 37 of the SPD 30 to protected socket 20.

Referring now to Figs 6A and 6B, in Fig.6A there is shown an exemplary replacement unit circuit board 39 in accordance with some embodiments of the present invention. In Fig.6B there is shown an exemplary base unit circuit board 37 in accordance with some embodiments of the present invention. In this example embodiment, interface connectors 41 and 43 capable of carrying 250 VAC at up to 16A. However, in other embodiments of the present invention the interface connectors may carry other AC voltages and currents. Referring also to Fig. 5C, the surge protection circuitry is based in this exemplary embodiment on three elements, 60, 62, 64 which are named RVl-iTMOV, RV2- TMOV and Gas Discharge Tube respectively. It should be noted that other suitable surge protection circuitry elements as known in the art can be used in other embodiments of the present invention. RVl-iTMOV 62 and RV2- TMOV 60 are Thermally protected Metal-Oxide Varistors (TMOV) with an integrated thermally activated element designed to open in the event of overheating due to the abnormal overvoltage, limited current, conditions such as but not limited to electrical surges and voltage spikes. The RV2-TMOV 60 and RVl-iTMOV 62 varistors offer quick thermal response due to the close proximity of the integrated thermal element to the MOV body. The integrated configuration also offers lower inductance than most discrete solutions resulting in improved clamping performance to fast overvoltage transients. The RVl-iTMOV 62 varistor differs from the RV2-TMOV 60 varistor by the inclusion of a third lead 66 for the purpose of indicating that the MOV has been disconnected from the circuit for example, after an event of abnormal overvoltage, limited current, conditions such as but not limited to electrical surges and voltage spikes. Lead 66 is connected to LED 68 to indicate the status of the SPD 30 status, if the SPD 30 is functioning or needs to be replaced, in this embodiment the LED 68 lights when the SPD functioning and stop to light when the SPD stop functioning or the replaceable unit 34 needs to be replaced with a new/working one. LED 70 on the SPD replaceable unit 34, indicates presence of power supply and that the AC line 36A is active.

Both versions of TMOV/iTMOV outlined in UL1449 standard for Surge Protective Devices (SPDs). The TMOV and iTMOV varistor’s integrated thermal element, in conjunction with appropriate enclosure design, helps facilitate SPD module compliance to UL1449 standard for both cords connected and permanently connected applications.

UL1449 standard is UL’s safety and performance standard for Surge Protective Devices (SPD), formerly known as Transient Voltage Surge Suppressors (TVSS). This standard applies to end-users, manufacturers, and specifiers. As a generalization, UL addresses electrical product safety in areas that involve a risk of fire, electric shock, or injury to persons. UL verifies the safe operation of SPDs through a listing or component recognition process including a series of stringent destructive and non-destructive tests. These ensure safe operation during normal operation and at the unit’s end of life.

Referring now also to Fig. 6B, in accordance of the present invention there is provided a means for delaying the AC power line to reconnect to the load (electric device) that is connected to the protected socket 20 when the AC power line is disconnected from socket 20 after electrical power interruption such as but not limited to surges and voltage spikes. Preferably the delaying means delaying the reconnection of the AC power line less than 3 minutes. It should be noted that in some embodiments of the present invention the delay time is adjustable. However, in other embodiments of the present invention the delay time is adjusted only once by the manufacturer of the SPD 30 and the user cannot change the delay time. In some embodiments of the present invention the SPD may include an input means that a user may have the option to adjust the delaying time in a limited delay time range. An example circuitry of a delaying time is described hereinafter. The electric circuit includes an AC to DC convertor 80 in this example the one that is used is the commercial AC to DC converter, IC chip LS01-15BXXSS series of MORNSUN®. The AC to DC converter 80 in this example is connected according to typical application from the manufacturer where fuse 82, protects The AC to DC converter 80 from over-current. RTC 84, inrush current limiter, serves as a second protection component for the IC chip 80. Capacitor 86 is for the AC input, Capacitor 86 is an input filter capacitor (which is required). Inductor 88 together with capacitor 86 forms a low-pass filter to minimize the effects of high frequency input noise. Capacitor 90 is a Class-Y capacitor that helps to minimize the generation of EMI/RFI and the negative effects associated with received EMI/RFI. Capacitors 92 and 94 are output filter capacitors (which are required), Capacitors 92, 94 and inductor 95 form a pi-type filter circuit, and they are high frequency and low impedance electrolytic capacitors. Capacitors 96 and 98 are ceramic capacitors, which are used to filter high frequency noise on the output DC voltage.

The delay time is created for example by utilizing a suitable timer means 100 such as but not limited to the commercial timer IC chip LM555. In this exemplary embodiment of the invention, the timer component 100 is triggered by a TRG voltage less than 5VDC/3. This voltage level is reached only after capacitor 102 is charged (through resistor 103) to 5VDC*2/3 so the remaining voltage on TRG pin is 5VDC/3. When triggered, the LM555 output pin 104 activates electrically operated AC line switch such as but not limited to a relay 106 and shorts "Line out" AC wire 42A to wire "line", 36A. The LM555 output pin 104 is also connected to the LED 70 to indicate that power is reconnected to the socket 20 (load) after delay. Diode 108 is a protection diode, to allow low resistance discharge loop for the coil of relay 106 and so protect the LM555 output internal transistor from overvoltage damage. Resistor 110 is a series resistor to limit the current flowing through the line 70A which is connected to indicator LED 70 that in the removable circuit 39, in case that the unit is operated without a delay option. In case of using the delay circuit resistor 110 is not connected and the indicator LED 70 is operated by the output signal of the delay circuit that comes from output pin 104. In case of using the SPD 30 without the delay all components of the delay circuit are not connected and "Line out" AC wire 42A is connected directly to wire "line", 36A and the indicator LED 70 is operated by the wire "line" voltage 36A to indicate presence of mains supply. LED 70 used as an indicator light when a proper mains power supply reached to the protected socket 20. The LED 70 lights ON only when the socket 20 is "live", meaning that in case of electricity disconnection it will only light ON after the delay is completed and the protected socket is "live" again.

In accordance with some embodiments of the present invention SPD 30 may include a wire/wireless communication module that will notify for example about the current operation mode of the device etc. The communication module can be connected as follows the module can receives DC a supply voltage from the output of the AC to DC converter 80. In order to receive current statuses of the current operation mode, the module input port connects parallel to the LEDs 68 and 70.

It should be understood that the above description is merely exemplary and that there are various embodiments of the present invention that may be devised, mutatis mutandis, and that the features described in the above-described embodiments, and those not described herein, may be used separately or in any suitable combination; and the invention can be devised in accordance with embodiments not necessarily described above.