Surge protector comprising means for detecting and permanently recording an overvoltage event and panelboard employing the same

Information

  • Patent Grant
  • 6411482
  • Patent Number
    6,411,482
  • Date Filed
    Tuesday, February 15, 2000
    24 years ago
  • Date Issued
    Tuesday, June 25, 2002
    21 years ago
Abstract
A surge protector is for electrical connection between one or more power lines and one or more loads. The surge protector includes an input for electrical connection to the power line and an output for electrical connection to the load. A circuit electrically interconnects the output with the input for passing power therebetween. A metal oxide varistor protects the load from surges or transients on the power line. A voltage monitoring circuit detects an occurrence of an overvoltage event on the power line. A charged capacitor is shorted by the series combination of a fuse and a MOSFET switch to open the fuse and, thereby, permanently record the occurrence of the overvoltage event.
Description




BACKGROUND OF THE INVENTION




1. Field of the Invention




This invention relates generally to apparatus for monitoring the voltage between a power source and a load and, more particularly, to a surge protector employing an overvoltage monitor for a power line. The invention also relates to a panelboard having an overvoltage monitor for a power line and a circuit for protecting a load from surges or transients in the power line voltage.




2. Background Information




Typically, relatively large commercial and industrial sites (e.g., electric utilities) employ equipment to monitor their power supplies or power sources. Economies of scale permit such monitoring at affordable prices. In contrast, however, small residential and light commercial locations do not monitor their source of power due to the relatively high cost of reliable voltage monitoring.




It is known to provide a power line analyzer which records or prints power line data such as, for example, short and long term voltage surges, sags, and transients. It is believed that such recorded or printed power line data, in turn, may be erased or be discarded by the user, thereby providing only temporary storage of such events.




The vast majority of damage to residential equipment is not caused by power line harmonics or blackouts, but, instead, by overvoltages. An overvoltage is an increase of steady state voltage (and, thus, power) for several cycles (e.g., at 60 Hz, 50 Hz) to several seconds. These overvoltages are caused, for example, by normal actions of the power system in clearing faults or correcting problems elsewhere in the system.




When the voltage of the power line sufficiently exceeds (e.g., as a function of both magnitude and time) its normal operating voltage, most electrical equipment is at risk of being damaged. Small surge suppression devices, which are common in most microprocessor-based equipment, are especially at risk of damage by overvoltages. For example, due to their fast response to surges and transients (e.g., a high frequency event lasting less than one power line cycle in duration), such suppression devices may, thus, react to and then be damaged by overvoltages.




Many manufacturers market surge protection devices for residential users. In this market, manufacturers have warranties to pay for damages to household equipment in the situation where the surge protection device fails to protect the residential equipment from surges or transients. However, the manufacturers' warranties are not valid if the damage was caused by an overvoltage. Many manufacturers determine if the surge protection device was damaged. If it was damaged, then the cause is assumed to be overvoltage and the warranty does not pay for the damage. If the surge protection device was not damaged, then the warranty also does not pay for the damage.




Various known devices and arrangements protect loads from surges in power supply voltage. Generally, both series and parallel protection are employed.




There is a need for a low-cost, fast, reliable voltage monitor which can neither be reset by the end user, nor lose its memory during extended periods in the absence of power. While various devices monitor overvoltage events, no known voltage monitoring device is suitable for such use in the residential market in combination with other residential products.




SUMMARY OF THE INVENTION




This and other needs are met by the present invention in which an overvoltage monitoring circuit of a surge protector or panelboard detects an occurrence of an overvoltage event on a power line, and a recording circuit permanently records the occurrence of the overvoltage event.




As one aspect of the invention, a surge protector for electrical connection between at least one power line and at least one load comprises: an input for electrical connection to the power line; an output for electrical connection to the load; means for electrically interconnecting the output with the input and for passing power therebetween; means for protecting the load from surges or transients on the power line; means for detecting an occurrence of an overvoltage event on the power line; and means for permanently recording the occurrence of the overvoltage event.




Preferably, the means for permanently recording further includes a capacitor and a switch, with the switch being electrically connected in series with a fuse, and with the series combination of the fuse and the switch being electrically connected in parallel with the capacitor; and the means for detecting includes means for charging the capacitor from the voltage of the power line.




As another refinement, the means for permanently recording includes means for visually indicating the overvoltage event in the presence of the voltage on the power line. Also, the means for permanently recording may include means for permanently changing from a first state to a different second state, and means for permanently recording the second state independent of subsequent power fluctuations or loss of power on the power line.




As another aspect of the invention, a panelboard for electrical connection between at least one power line and at least one load comprises: at least one enclosure; an input for electrical connection to the power line; an output for electrical connection to the load; means for electrically interconnecting the output with the input and for passing power therebetween; means for protecting the load from surges or transients on the power line; means for detecting an occurrence of an overvoltage event on the power line; and means for permanently recording the occurrence of the overvoltage event.











BRIEF DESCRIPTION OF THE DRAWINGS




A fall understanding of the invention can be gained from the following description of the preferred embodiments when read in conjunction with the accompanying drawings in which:





FIG. 1

is a block diagram of a surge protector in accordance with an embodiment of the present invention;





FIG. 2

is a block diagram of an overvoltage detection circuit and a permanent recording circuit for the surge protector of

FIG. 1

;





FIG. 3

is a block diagram in schematic form of an overvoltage detection circuit and a permanent recording circuit in accordance with another embodiment of the invention;





FIG. 4

is a block diagram of a panelboard and a surge protection device in accordance with another embodiment of the invention;





FIG. 5

is a block diagram of a surge protection and voltage monitoring device in accordance with another embodiment of the invention;





FIG. 6

is a block diagram of a surge protection and voltage monitoring device in accordance with another embodiment of the invention; and





FIGS. 7A-7D

are block diagrams of various electrical connections employed by the surge protection and voltage monitoring device of FIG.


6


.











DESCRIPTION OF THE PREFERRED EMBODIMENTS




As employed herein, the term “surge” shall expressly include, but not be limited to, a sub-cycle disturbance in an alternating current waveform that includes a high frequency event or a sharp discontinuity of the waveform.




As employed herein, the term “transient” shall expressly include, but not be limited to, surges.




As employed herein, the term “overvoltage event” shall expressly include, but not be limited to, an increase of steady state voltage for more than one power line cycle (e.g., at 60 Hz, 50 Hz) but, otherwise, shall exclude surges and transients.




Referring to

FIG. 1

, a surge protector


2


for electrical connection between one or more power lines


4


and one or more loads


6


is illustrated. The surge protector


2


includes an input


8


for electrical connection to the power lines


4


, an output


10


for electrical connection to the loads


6


, a suitable electrical connection


12


between the input


8


and the output


10


for passing power therebetween, a circuit


14


(e.g., a metal oxide varistor (MOV)) for protecting the loads


6


from surges or transients on the power lines


4


, an overvoltage detection circuit


16


for detecting an occurrence of an overvoltage event on the power lines


4


, and a circuit


18


for permanently recording the occurrence of the overvoltage event.




Although parallel protection in the form of an MOV is provided in the exemplary embodiment, a wide range of surge and/or transient protection may be employed such as other forms of parallel protection (e.g., other voltage clamping devices such as zener diodes; crowbar devices such as gas discharge tubes, thyristors, silicon controlled rectifiers (SCRs), TRIACs) in which the surge current is diverted with a low impedance shunt, or series protection in which a high impedance is used in series with the load during a surge to block or limit surge current.





FIG. 2

shows the overvoltage detection circuit


16


and the permanent recording circuit


18


of FIG.


1


. The exemplary circuit


16


includes a diode


20


, a voltage divider and filter


22


, a voltage regulator


24


, a voltage divider and filter


26


, and a comparator


28


. In the preferred embodiment, the power line


4


of

FIG. 1

includes a power leg (Φ) and a neutral conductor (N) having an alternating current (AC) voltage therebetween, although the present invention is applicable to direct current (DC) power sources. The exemplary diode


20


rectifies the AC power line voltage to provide a half-wave rectified voltage


30


to the voltage divider and filter


22


, although any suitable rectifier (e.g., a diode bridge which provides full-wave rectification) may be employed. The voltage divider and filter


22


preferably provide an output signal


32


which is proportional to the peak of the input voltage. Also, the filter portion removes any fast rising transient or noise from the signal


32


.




In the exemplary embodiment, a resistor


34


limits current to the voltage regulator


24


, which preferably provides a relatively constant voltage


36


to the rest of the circuit


16


and to the circuit


18


. Preferably, the voltage regulator


24


has suitable power to drive those circuits and, also, to provide charging current for capacitor


38


of the circuit


18


.




The second voltage divider and filter


26


provide an output signal


40


which is proportional to the regulator's output voltage


36


. The filter portion removes any fast rising transient or noise from the output signal


40


, as well as maintaining a relatively constant delay with respect to the delay of the first voltage divider and filter


22


, to prevent triggering during turn-on. Hence, a surge or transient affects both inputs (+,−) of the comparator


28


about equally. In this manner, the overvoltage detection circuit


16


is relatively immune to surges and transients which might affect the output voltage


42


of the comparator


28


.




The comparator


28


compares the output signals


32


,


40


of the respective first and second voltage dividers and filters


22


,


26


. Normally, the voltage of the second output signal


40


is higher than the voltage of the first output signal


32


. Since the second output signal


40


is connected to the negative (−) input of the comparator


28


, the output voltage


42


of the comparator


28


is normally low. This maintains the switch


46


of circuit


18


in an off state.




The permanent recording circuit


18


includes the capacitor


38


, a fuse


44


and a suitable switch


46


. The voltage regulator


24


charges the capacitor


38


from the voltage of the power line. The switch


46


is electrically connected in series with the fuse


44


. The series combination of the fuse


44


and the switch


46


is electrically connected in parallel with the capacitor


38


. If an overvoltage event occurs, the voltage output by the first voltage divider


22


exceeds the voltage of the second voltage divider


26


. In that case, the comparator


28


changes states and provides a high output signal


42


which causes the switch


46


to turn on. Then, the energy from the capacitor


38


is dumped through the fuse


44


and the switch


46


.




Thus, if an overvoltage event occurs, the voltage of the first output signal


32


exceeds the voltage of the second output signal


40


, the comparator


28


changes states, and the high output signal


42


causes the switch


46


to turn on which opens the fuse


44


. Otherwise, the switch


46


is off and there is no current therethrough or through the fuse


44


. The voltage divider and filter


22


sense the half-wave rectified voltage


30


. The circuit


16


determines an overvoltage condition when the sensed voltage


32


exceeds the reference voltage


40


, with the sensed voltage


32


remaining less than the reference voltage


40


for surges or transients on the power line and, otherwise, being greater than the reference voltage


40


for the overvoltage event on the power line. Hence, the circuit


16


distinguishes between the occurrence of the overvoltage event and surges or transients on the power line.




The output signal


42


of the comparator


28


switches the switch


46


from an off state to an on state, in order that the on state electrically connects the fuse


44


in parallel with the capacitor


38


in order to permanently open the fuse


44


. The energy (i.e., in the form of the electric field, E=½CV


2


) from the capacitor


38


is then dumped as current through the fuse


44


and the switch


46


, and the fuse


44


permanently changes from a first closed state to an open second state. In this manner, the fuse


44


permanently records that open state independent of subsequent power fluctuations or loss of power on the power line. Otherwise, when there is no overvoltage event on the power line, the voltage of the first signal


32


remains less than the voltage of the second reference signal


40


for surges or transients on the power line.




Referring to

FIG. 3

, an overvoltage detection circuit


50


and a permanent recording circuit


52


for a plurality of power legs ΦA,ΦB are shown. For each of these power legs, a voltage divider and filter


22


include (as shown with power leg ΦA) a first resistor


54


in series with a second resistor


56


, and a capacitor


58


in parallel with the second resistor


56


. The voltage


32


A, which is applied to the positive (+) input of the comparator


28


A, is across the parallel combination of the capacitor


58


and the second resistor


56


.




The overvoltage detection circuit


50


also includes a suitable voltage regulator formed by a resistor


60


A and a zener diode


62


. In the exemplary embodiment, a 24V zener diode


62


is employed, although the invention is applicable to a wide range of such voltages. Although the exemplary capacitor


38


is shown as being part of the permanent recording circuit


52


, it will be appreciated that such capacitor may include one or more parallel capacitors of one or both of the circuits


50


and/or


52


.




The second voltage divider and filter


26


provide the second reference voltage


40


to the negative (−) inputs of the comparators


28


A,


28


B for each of the power legs ΦA,ΦB. The divider and filter


26


include a first resistor


64


in series with a second resistor


66


. A capacitor


68


is in parallel with the second resistor


66


, with the second reference voltage


40


being across the parallel combination of the capacitor


68


and resistor


66


. The zener diode


62


is in parallel with the series combination of the resistors


64


,


66


, with the cathode of the zener diode


62


being electrically connected to the resistor


64


at node


70


. The resistor


60


A is electrically interconnected between the cathode of diode


20


A at the input for power leg ΦA, and the cathode of zener diode


62


. Similarly, the resistor


60


B is electrically interconnected between the cathode of diode


20


B at the input for power leg ΦB, and the cathode of zener diode


62


. Hence, one or both of the power legs may power the circuits


50


,


52


.




For example, the exemplary zener diode


62


is a 24 V zener, the exemplary capacitor


38


is 10 μF, and the exemplary fuse


44


is rated at 1/16 A. Although not shown, a relative small resistance may be electrically connected in series with the fuse


44


and MOSFET


46


A. In the exemplary embodiment, the fuse


44


functions as a memory element. Initially, the fuse


44


is closed and, thus, may conduct current. As long as this remains the case, there has been no overvoltage event. Otherwise, when the MOSFET switch


46


A is on, and with suitable selection of the components, the resulting relatively high current from the capacitor


38


causes the fuse


44


to open. Hence, the fuse state permanently changes (i.e., from closed to open) and cannot be reset. In this regard, the fuse


44


is preferably employed in a manner which prohibits (e.g., without limitation, potted, sealed, soldered in place) or discourages (e.g., with a label stating that unauthorized repair voids the warranty) replacement of the same by a user.




Preferably, the voltage across the MOSFET


46


A is monitored to provide a visual indication of the presence or absence of the overvoltage event. The exemplary permanent recording circuit


52


includes a monitoring circuit


71


having MOSFETs


72


,


74


, light emitting diode (LED)


76


, and resistors


78


,


80


,


82


. Normally, the voltage at node


84


is the same as the voltage of the zener diode


62


, which is dependent upon the presence of the voltage on the power line. In that case, the MOSFET


72


is on, the MOSFET


74


is off, and the LED


76


is off. Otherwise, after an overvoltage event, the voltage at node


84


is about zero volts, the MOSFET


72


is off, the MOSFET


74


is on, and the LED


76


is turned on.




The portion of the overvoltage detection circuit


50


for the second power leg ΦB includes the diode


20


B, resistor


60


B, the voltage divider and filter


22


, the comparator


28


B, and the MOSFET


46


B. The voltage divider and filter


22


output voltage


32


B, which is applied to the positive (+) input of the comparator


28


B. The comparator


28


B, in turn, controls the MOSFET


46


B, which is electrically connected in parallel with the MOSFET


46


A. In this manner, an overvoltage event on one or both of the phase legs ΦA, ΦB may be detected, permanently recorded by fuse


44


, and/or visually displayed by LED


76


. Although two exemplary phase legs are shown, the invention is applicable to one, two, three or more phases.





FIG. 4

shows a panelboard


90


and a surge protection device


92


in accordance with an embodiment of the invention. The panelboard


90


is for electrical connection between a plurality of power lines


94


and a plurality of loads, such as the exemplary household loads


98


. An example of a panelboard for at least one power line and a plurality of loads is disclosed in U.S. Pat. No. 5,861,683, which is incorporated by reference herein. As is well known in the art, the panelboard


90


includes an enclosure


100


, an input


102


for electrical connection to the power lines


94


, and output


103


for electrical connection to the loads


98


. As discussed below in connection with

FIG. 7B

, the panelboard


90


includes a plurality of circuit breakers (CBs)


104


for electrically interconnecting the output


103


with the input


102


and for passing power therebetween.




In the exemplary embodiment, a second enclosure


105


is provided for the surge protection device


92


, which includes a suitable circuit


106


for protecting the loads


98


from surges or transients on the power lines


94


, and an overvoltage monitor


108


. The exemplary overvoltage monitor


108


, which is similar to the circuits


50


and


52


of

FIG. 3

, detects an occurrence of an overvoltage event on the power lines


94


and permanently records the occurrence of the overvoltage event. Preferably, the CBs


104


are housed by the first enclosure


100


, and the surge protection device


92


, which includes circuit


106


and overvoltage monitor


108


, is housed by the second enclosure


105


, which is external to the first enclosure


100


. Preferably, a suitable electrical connection


110


(e.g., wires, other suitable conductors) is provided to electrically connect the power line legs and neutral (and/or ground) from the panelboard


90


to the surge protection device


92


. Alternatively, the second enclosure


105


may be housed within the first enclosure


100


.




Referring to

FIG. 5

, a surge protection and voltage monitoring device


112


is shown. The device


112


includes a suitable circuit


114


for protecting a load


115


from surges or transients on the power line


116


, and an overvoltage monitor


117


, which is similar to the circuits


50


and


52


of FIG.


3


. The overvoltage monitor


117


detects an occurrence of an overvoltage event on the power line


116


and permanently records the occurrence of the overvoltage event. Preferably, an enclosure


118


provides an input


119


from the power line


116


and an output


120


to the load


115


, and houses the circuit


114


for protecting the load


115


and the overvoltage monitor


117


.





FIG. 6

shows another exemplary surge protection and voltage monitoring device in the form of a surge strip


122


. The surge strip


122


has a male plug


124


for electrical connection to a power line (not shown) and one or more female plugs


126


for electrical connection to loads (not shown). The surge strip


122


includes a suitable circuit


128


for protecting the loads from surges or transients on the power line, and an overvoltage monitor (OVM)


130


, which is similar to the circuits


50


and


52


of FIG.


3


. The OVM


130


detects an occurrence of an overvoltage event on the power line and permanently records the occurrence of the overvoltage event.




In this embodiment, the exemplary OVM


130


is included as part of a home surge protector


122


. By monitoring for overvoltage events, the exemplary OVM


130


removes some of the potential liability associated with any warranty which may be offered to users of the home surge protector


122


for damage to downstream equipment caused by surges or transients. Hence, an overvoltage event, which might cause damage to any downstream electrical equipment, is readily detected, thereby precluding warranty claims for damage caused by mere surges or transients. Typically, the electrical connection (C)


132


between the power line leg (Φ) and the surge protection circuit


128


(e.g., an MOV) is provided by a switch


134


(as shown in FIG.


7


D). Alternatively, as shown in

FIGS. 7A

,


7


B and


7


C, various other types of electrical connections may be employed, such as, for example, a direct electrical connection


136


between the input and the surge protection circuit


128


, the CB


104


, and a fuse


138


, respectively.




The exemplary surge protectors


2


,


92


,


112


,


122


employ a voltage monitoring circuit which monitors an AC power line and determines if an overvoltage event has occurred. It then changes state and permanently records the overvoltage event without regard to subsequent power fluctuations or loss of power. Preferably, a separate visible indication of the overvoltage event is provided.




The exemplary voltage monitoring circuit has a relatively low cost and adds minimal, if any, cost to the end user price of the exemplary surge protectors and panelboards. This circuit monitors for overvoltages that might damage downstream equipment but cannot be stopped by conventional surge or transient protection. Otherwise, the exemplary voltage monitoring circuit is not triggered during actual surge, transient or low voltage events.




The exemplary voltage monitoring circuit fits into the cost and size structure of the residential market. By employing the voltage from the power line, there is no need for an external power supply. Preferably, the voltage monitoring circuit is integrally mounted along with a suitable surge and/or transient protection device.




While specific embodiments of the invention have been described in detail, it will be appreciated by those skilled in the art that various modifications and alternatives to those details could be developed in light of the overall teachings of the disclosure. Accordingly, the particular arrangements disclosed are meant to be illustrative only and not limiting as to the scope of invention which is to be given the full breadth of the claims appended and any and all equivalents thereof.



Claims
  • 1. A surge protector for electrical connection between at least one power line and at least one load, said surge protector comprising:an input for electrical connection to said power line; an output for electrical connection to said load; means for electrically interconnecting said output with said input and for passing power therebetween; means for protecting said load from surges or transients on said power line; means for detecting an occurrence of an overvoltage event on said power line; and means for permanently recording said occurrence of said overvoltage event without interrupting said power passing between said input and said output.
  • 2. The surge protector as recited in claim 1, wherein said means for permanently recording includes a fuse which permanently changes from a closed state to an open state.
  • 3. The surge-protector as recited in claim 2, wherein said power line has a voltage; wherein said means for permanently recording further includes a capacitor and a switch, with the switch being electrically connected in series with the fuse, and with the series combination of the fuse and the switch being electrically connected in parallel with the capacitor; and wherein said means for detecting includes means for charging said capacitor from the voltage of said power line.
  • 4. The surge protector as recited in claim 3, wherein said means for detecting includes means for switching said switch from an off state to an on state, in order that said on state electrically connects the fuse in parallel with the capacitor in order to permanently open the fuse.
  • 5. The surge protector as recited in claim 1, wherein said power line has a voltage; and wherein said means for detecting includes:means for dividing and filtering the voltage of said power line to provide a first voltage; means for providing a second reference voltage; means for comparing said first voltage and said second reference voltage and detecting said occurrence of said overvoltage event when said first voltage exceeds said second reference voltage.
  • 6. The surge protector as recited in claim 5, wherein said means for dividing and filtering includes a first resistor in series with a second resistor, and a capacitor in parallel with the second resistor, with said first voltage being across the parallel combination of the capacitor and the second resistor.
  • 7. The surge protector as recited in claim 5, wherein said means for providing a second reference voltage includes a voltage regulator powered by said power line.
  • 8. The surge protector as recited in claim 5, wherein said means for providing a second reference voltage includes:a first resistor in series with a second resistor, a capacitor in parallel with the second resistor, with said second reference voltage being across the parallel combination of the capacitor and the second resistor, a zener diode in parallel with the series combination of the first resistor and the second resistor, said zener diode having a cathode electrically connected to said first resistor, and a third resistor electrically interconnected between said input and said first resistor and the cathode of said zener diode.
  • 9. The surge protector as recited in claim 8, wherein said second reference voltage is normally greater than said first voltage, and wherein said first voltage remains less than said second reference voltage for surges or transients on said power line and is greater than said second reference voltage for said overvoltage event on said power line.
  • 10. The surge protector as recited in claim 5, wherein the voltage of said power line is an alternating current (AC) voltage; and wherein said means for detecting further includes means for rectifying the AC voltage to provide a rectified voltage to said means for dividing and filtering.
  • 11. The surge protector as recited in claim 1, wherein said surge protector is a surge strip having a male plug for electrical connection to said power line and at least one female plug for electrical connection to said load.
  • 12. The surge protector as recited in claim 1, wherein said input includes means for electrically connecting to a panelboard.
  • 13. The surge protector as recited in claim 1, wherein said means for electrically interconnecting said output with said input is selected from the list including: (a) a circuit breaker, (b) a fuse, (c) a switch, and (d) a first direct electrical connection between said input and said means for protecting, and a second direct electrical connection between said means for protecting and said output.
  • 14. The surge protector as recited in claim 1, wherein said power line has a voltage; and wherein said means for permanently recording includes means for visually indicating said overvoltage event in the presence of the voltage on said power line.
  • 15. The surge protector as recited in claim 1, wherein said means for protecting includes a metal oxide varistor.
  • 16. The surge protector as recited in claim 1, wherein said power line has a voltage with a peak; and wherein said means for detecting includes means for distinguishing between said occurrence of said overvoltage event and said surges or transients on said power line, said means for distinguishing comprising a first voltage divider having an input electrically connected with said power line and an output; a first filter electrically connected with the output of said first voltage divider, said first voltage divider and said first filter cooperating to provide a first output having a signal which is proportional to the peak of the voltage of said power line; a voltage regulator having an input electrically connected with said power line and an output having a voltage; a second voltage divider having an input electrically connected with the output of said voltage regulator and an output; a second filter electrically connected with the output of said second voltage divider, said second voltage divider and said second filter cooperating to provide a second output having a signal which is proportional to the voltage of the output of said voltage regulator; and a comparator having a first input electrically connected to said first output, a second input electrically connected to said second output, and an output having a signal representing said occurrence of an overvoltage event on said power line.
  • 17. The surge protector as recited in claim 1, wherein said means for permanently recording includes means for permanently changing from a first state to a different second state.
  • 18. The surge protector as recited in claim 17, wherein said means for permanently recording includes means for permanently recording said second state independent of subsequent power fluctuations or loss of power on said power line.
  • 19. A panelboard for electrical connection between at least one power line and at least one load, said panelboard comprising:at least one enclosure; an input for electrical connection to said power line; an output for electrical connection to said load; means for electrically interconnecting said output with said input and for passing power therebetween; means for protecting said load from surges or transients on said power line; means for detecting an occurrence of an overvoltage event on said power line; and means for permanently recording said occurrence of said overvoltage event without interrupting said power passing between said input and said output.
  • 20. The panelboard as recited in claim 19, wherein said at least one power line includes a first power line leg and a second power line leg; and wherein said means for detecting includes means for monitoring said first and second power line legs.
  • 21. The panelboard as recited in claim 19, wherein said at least one enclosure includes a first enclosure and a second enclosure; wherein said means for electrically interconnecting is housed by the first enclosure; and wherein said means for protecting, said means for detecting and said means for permanently recording are housed by the second enclosure.
  • 22. The panelboard as recited in claim 21, wherein the second enclosure is external to the first enclosure.
  • 23. The panelboard as recited in claim 19, wherein said power line has a voltage; and wherein said means for detecting includes means for sensing said voltage, means for comparing said sensed voltage to a reference voltage and for determining an overvoltage condition when said sensed voltage exceeds said reference voltage, with said sensed voltage remaining less than said reference voltage for surges or transients on said power line and being greater than said reference voltage for said overvoltage event on said power line.
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3700968 Spies Oct 1972 A
4563720 Clark Jan 1986 A
4566052 Kammiller Jan 1986 A
4587588 Goldstein May 1986 A
4890186 Matsubara et al. Dec 1989 A
4912589 Stolarczyk Mar 1990 A
5204800 Wasney Apr 1993 A
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