Controller circuit including a switch mode power converter and automatic recloser using the same

The present application claims the benefit of U.S. Provisional Patent Application No. 61/367,584, filed Jul. 26, 2010, the disclosure of which is hereby incorporated herein by reference in its entirety.

The present invention relates to controller circuits including a switch mode power regulator and applications of the same.

Devices such as circuit breakers, autoreclosers, anti thief devices, energy (electrical) meters and electrical energy distribution components are sometimes used in connection with the delivery and use of AC electrical power.

Many of these devices, including photo controllers, may make use of power converters to convert relatively high voltage alternating current to relatively low voltage direct current as is used in many conventional electronic devices. Some conventional power converters make use of large, high-voltage resistors to drop the voltage. However, these resistors are typically inefficient and generate high heat. The heat generated from the resistors may require that the resistors be housed in a large package and include heat dissipating elements, such as heat sinks. Also, the high heat generated by the resistors can lead to problems with reliability and longevity in the resistors and in other electronic components situated near the resistors.

Another conventional approach to power conversion is the use of a switch mode power converter (regulator). The switch mode power converters typically require six transistors or a micro-controller to implement. The requirement for multiple transistors or a micro-controller may cause the implementation of switch mode power converters to be cost prohibitive in some applications, such as in photo controllers or current limiters.

A small, low cost, efficient switch mode power converter (regulator) is described in U.S. Pat. No. 6,903,942 (“the '942 patent”), which is hereby incorporated herein by reference as if set forth in its entirety. The switch mode power converter of the '942 patent is illustrated in FIG. 1 . The circuit shown in FIG. 1 is a switch mode power regulator, which implements power line synchronized pulse width modulation (firing angle modulation). The circuit comprises a power circuit and a control circuit. The power circuit comprises an output stage, which comprises a transistor Q 3 . The transistor's collector circuit comprises a relay K 1 and a diode D 6 , known as a snubber diode, in parallel with the relay K 1 .

The circuit further comprises a first capacitor C 6 coupled to the base of the transistor Q 3 , a first resistor R 4 coupled in series to the first capacitor C 6 , and a second resistor R 8 coupled in series to the first resistor R 4 . The circuit shown further comprises a first diode D 7 coupled in parallel with the second resistor R 8 . The circuit further comprises a third resistor R 5 coupled to the base of the first transistor Q 3 and a Zener diode D 1 , whose cathode is connected to the first capacitor C 6 and a second diode D 5 , and whose anode is connected to the third resistor R 5 .

The circuit also comprises a fourth resistor R 6 coupled in series with the third diode D 5 , a relay K 1 coupled in series with the fourth resistor R 6 , a third diode D 6 coupled in parallel with the relay K 1 , a second capacitor C 5 coupled to the fourth resistor R 6 , a fifth resistor R 7 coupled in series with the second capacitor C 5 ; and a plug, comprising a load, a neutral, and a line, wherein the load is coupled to the relay K 1 , the neutral is coupled to the emitter of the transistor Q 3 , and the line is coupled to the variable resistor, MOV 1 .

Transistor Q 3 regulates the average voltage across the relay coil K 1 by means of pulse width modulation. In the embodiment shown, transistor Q 3 comprises a bipolar transistor, however, transistor Q 3 may instead be a field-effect transistor (FET), or an insulated gate bipolar transistor (IGBT), provided a diode is placed cathode to drain and anode to source.

Transistor Q 3 starts conducting at the start of the power line cycle (0 degrees) and continues conducting until enough current has flowed to maintain the relay voltage at the desired level. When transistor Q 3 turns off, a voltage will be induced across the relay coil K 1 by magnetic induction. This voltage is partially suppressed by diode D 6 in order to prevent the failure of transistor Q 3 due to over voltage.

The circuit shown in FIG. 1 utilizes half-wave rectification. Half-wave rectification is less expensive that full-wave rectification and requires less components. Since the relay K 1 is highly inductive, it does not require a particularly clean DC signal. For example, the DC signal may include a large amount of ripple, which will not affect the operation of relay K 1 . Half wave rectification allows the circuit to operate in two modes, positive and negative. During the positive half, the transistor Q 3 generates a current pulse, which is regulated by the average voltage across the relay K 1 . This process is pulse width modulation.

The control circuit shown in FIG. 1 comprises a pulse generator whose pulse width varies proportionately with the difference between the Zener voltage of diode D 1 and the average voltage across the relay K 1 . At the start of the power line cycle (0 degrees), a current will begin to flow through diode D 7 , resistor R 4 , capacitor C 6 , and the base of transistor Q 3 . The current will cause transistor Q 3 to turn on, starting a pulse.

Diode D 7 and Resistor R 8 provide half-wave power rectification. Resistor R 8 is applied across the power rectifier D 7 , applying a negative current during the negative half of the line cycle. Resistor R 8 allows a small negative current to be applied. Resistor R 8 provides the negative current that switches on transistor Q 3 during the negative half of the line cycle. That negative charge conducted through R 8 must exceed the charge that conducts through capacitor C 6 to assure transistor Q 3 will turn on. Negative current switches on rectifier D 6 and turns on transistor Q 3 , providing a current path between the low voltage side of capacitor C 5 through resistor R 7 .

In the embodiment shown, without resistor R 7 , transistor Q 3 would not saturate during the current pulse, causing excessive power to be dissipated in transistor Q 3 . The transistor Q 3 collector voltage would drop until diode D 5 would conduct, diverting base current from transistor Q 3 and preventing transistor Q 3 from saturating. During the transistor Q 3 current pulse, a voltage is generated across resistor R 7 that will keep diode D 5 from conducting and preventing transistor Q 3 saturation. To prevent diode D 5 from conducting during the positive half of the line cycle, a voltage of at least the capacitor C 6 ripple voltage must drop across resistor R 7 . Transistor Q 3 does not start conducting until the instantaneous line voltage is approximately twice the Zener voltage of diode D 1 .

Capacitor C 5 filters the voltage across the relay K 1 . If the value of C 5 is too small, the relay coil current will oscillate on and off during power up causing the relay contacts to chatter. Therefore, capacitor C 5 shown is large enough a value to prevent this chattering of the relay contacts.

Capacitor C 6 is pre-set to the output voltage and provides a timing functionality. During the positive half of the line cycle, a current flows through resistor R 4 to capacitor C 6 , causing it to start charging, and through the base of transistor Q 3 , which will turn transistor Q 3 on. Transistor Q 3 remains on as long a current flows through capacitor C 6 . Increasing the value of capacitor C 6 has the positive effect of increasing the gain of the feed back loop of the regulator circuit. However, increasing the value also slows the time it takes for the current pulse of transistor Q 3 to be turned off, increasing commutation losses in transistor Q 3 , and increases the time for the regulator circuit to stabilize at startup.

As this current flows, the voltage across capacitor C 6 increases. When the voltage across capacitor C 6 plus the base to emitter voltage of transistor Q 3 reaches the Zener voltage of diode D 1 , the current flowing through capacitor C 6 ceases because the current is diverted to the Zener diode D 1 . Zener diode D 1 provides the reference voltage to which the relay coil voltage will be regulated. When the current through capacitor C 6 ceases, no current flows to the base of transistor Q 3 , turning it off and ending the pulse.

During the negative half of the line cycle, a current flows through resistor R 8 , diode D 6 , the collector and base of transistor Q 3 , and resistor R 5 . This current will turn transistor Q 3 on. Also, during the negative half of the power line cycle, resistor R 5 provides part of the current path through which capacitor C 6 discharges into C 5 .

During the positive half of the line cycle at the end of the current pulse, resistor R 5 causes transistor Q 3 to more rapidly turn off, reducing energy losses during the commutation of transistor Q 3 . Resistor R 5 will shunt some of the current that would otherwise go through the base of transistor Q 3 during the pulse of transistor Q 3 base current. If the current shunted is too much, the base current of transistor Q 3 will not be enough to turn transistor Q 3 completely on.

Capacitor C 6 will now discharge into capacitor C 5 until their voltages equalize. The voltage across capacitor C 5 is equal to the average voltage across the relay coil K 1 . Diode D 7 disconnects during the negative half of the power line cycle assuring that the relay current is direct current. As such, the discharge of capacitor C 6 into capacitor C 5 determines the pulse width for operation of the transistor Q 3 , which in turn allows current flow to establish the average mean voltage of relay coil K 1 .

The circuit shown in FIG. 1 also comprises a voltage averaging circuit, further comprising resistor R 6 , capacitor C 5 , and resistor R 7 . The averaging circuit essentially measures the average voltage across the relay coil K 1 . The average voltage across capacitor C 5 is the voltage to which the circuit is regulated. The purpose of resistor R 7 , apart from forming part of the averaging circuit is also to ensure that diode D 5 will not conduct during the positive half of the power line cycle. The current to resistor R 8 flows through diode D 6 , turning it on, and then the current flows through the collector of transistor Q 3 , causing it to turn on. When transistor Q 3 turns on, it creates a base current between the emitter of transistor Q 3 and the negative end of capacitor C 5 . When the current begins flowing, diode D 5 starts conducting, which causes capacitor C 6 to discharge until at the same voltage as capacitor C 5 . The capacitors reach equal voltage at the average output voltage.

This feedback of the output voltage into the pulse forming circuit determines how long each cycle transistor Q 3 will be turned on. (The feed back loop is as follows. Average voltage of relay coil K 1 voltage→voltage of capacitor C 5 →voltage of capacitor C 6 →duty cycle of transistor Q 3 commutation→average voltage of relay coil K 1 voltage.) If the average voltage across the relay coil K 1 is too low, the voltage across capacitor C 6 will be less than the Zener voltage of diode D 1 resulting in a longer on time of transistor Q 3 , which will cause the average relay coil voltage to increase. If the average voltage across the relay coil K 1 is too high the voltage across capacitor C 6 will approximate the Zener voltage of diode D 1 , resulting in a shorter on time of transistor Q 3 , which will cause the average relay coil voltage to decrease.

The circuit shown in FIG. 1 also comprises a plug J 1 , J 2 , J 3 . Plug J 1 , J 2 , J 3 may be a twist lock Hubble type connector, used to connect a line voltage, neutral voltage, and load. The circuit also comprises a metal oxide variable resistor MOV 1 . MOV 1 is not necessary for the operation of the circuit. It provides a level of protection, eliminating high voltage transients like might come from a lightning strike.

The '942 patent further describes the use of the above described power regulator to provide a photo controller for street lighting and the like. Likewise, U.S. patent application Ser. No. 12/700,251 (“the '251 application), which is hereby incorporated by reference herein as if set forth in its entirety herein, describes photocontrol circuits that may use power regulators. These circuits generally use a Zener diode to provide a DC voltage, typically 15 volts, to power the photo control circuits, such as diode D 1 seen in FIG. 1 (or diode D 3 in FIG. 2 ). However, the resultant DC voltage may have its quality limited by an AC component from the half wave rectifier and may also be subjected to fluctuation due to variations in the voltage level of the AC power signal used to generate the DC power signal.

An autorecloser circuit breaker is available from Sustainable Control Systems Limited (“SCS”) that may be used, for example, as an alternative to metered delivery of power to a customer. An autorecloser is a circuit breaker equipped with a mechanism that can automatically close the breaker after it has been opened due to a fault. The SCS device uses a TRIAC as a relay. Such devices generally require the use of some form of heat sink to dissipate heat generated by the circuit without overheating and damaging the circuit.

Some embodiments of the present invention provide an autorecloser circuit including a relay circuit. The relay circuit includes an electromagnetic relay configured to be coupled between an AC power source and a customer location to deliver current from the AC power source to the customer location. A controller coupled to the relay circuit is configured to control the electromagnetic relay to disconnect the AC power source from the customer location and to reconnect the AC power source to the customer location. A current sense circuit coupled to the controller is configured to detect an amount of the current that is delivered to the customer location and a reference voltage circuit coupled to the controller is configured to establish a reference level for the amount of the current that is delivered to the customer location. A power circuit coupled to the controller and to the relay circuit is configured to provide a DC power source to the controller and to the relay circuit from the AC power source. The controller is configured to disconnect the AC power source from the customer location when the detected amount of current exceeds the reference level and to reconnect the AC power source to the customer location responsive to detection of a reconnect condition.

In other embodiments, an autorecloser circuit includes a relay circuit that includes an electromagnetic relay configured to be coupled between an AC power source and a customer location to deliver current from the AC power source to the customer location. A controller coupled to the relay circuit is configured to control the electromagnetic relay to disconnect the AC power source from the customer location and to reconnect the AC power source to the customer location. A current sense circuit coupled to the controller includes a current shunt resistor and an anti-aliasing filter circuit. The current shunt resistor is configured to detect an amount of the current that is delivered to the customer location. A reference voltage circuit coupled to the controller is configured to establish a reference level for the amount of the current that is delivered to the customer location. The reference voltage circuit includes a variable resistor configured to adjust the reference level and the controller includes a comparator having a first input coupled to the current sense circuit and a second input coupled to the reference voltage circuit. A power circuit coupled to the controller and to the relay circuit is configured to provide a DC power source to the controller and to the relay circuit from the AC power source. The power circuit includes a half-wave rectifier coupled to the AC power source and the power circuit is configured to provide from the half-wave rectifier a first voltage level as the DC power source to the relay circuit and a second voltage level, lower than the first voltage level, as the DC power source to the controller. The controller is configured to disconnect the AC power source from the customer location when the detected amount of current exceeds the reference level and to reconnect the AC power source to the customer location responsive to detection of a reconnect condition.

FIG. 1 is a circuit diagram of a power regulator according to the prior art.

FIG. 2 is a circuit diagram of a photosensor described in the '251 application.

FIG. 3 is a circuit diagram of a controller circuit including a power regulator according to some embodiments of the present invention.

FIG. 4 is a circuit diagram of a controller circuit including a power regulator according to other embodiments of the present invention.

FIG. 5 is an exploded perspective view of an autorecloser circuit with a housing according to some embodiments of the present invention.

The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which illustrative embodiments of the invention are shown. In the drawings, the relative sizes of regions or features may be exaggerated for clarity. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the present invention.

Spatially relative terms, such as “beneath”, “below”, “lower”, “above”, “upper” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the exemplary term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90° or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless expressly stated otherwise. It will be further understood that the terms “includes,” “comprises,” “including” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. It will be understood that when an element is referred to as being “connected” or “coupled” to another element, it can be directly connected or coupled to the other element or intervening elements may be present. Furthermore, “connected” or “coupled” as used herein may include wirelessly connected or coupled. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of this specification and the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

FIG. 2 illustrates a photo control circuit with a switch mode power converter. FIG. 2 corresponds to FIG. 7 of the '251 application. The circuit shown in FIG. 2 includes a current amplifier Q 3 coupled between the voltage averaging circuit C 5 , R 8 , R 9 and the select transistor Q 4 . The current amplifier Q 3 amplifies a current discharged from the capacitor C 5 of the voltage averaging circuit to a base of the drive transistor Q 5 during the negative half of the AC power source to reduce an amount of current discharged from the capacitor C 5 of the voltage circuit during the negative half of the AC power source.

The pulse width modulator circuit of FIG. 2 further includes a duty cycle capacitor C 6 that discharges a current to the base of the drive transistor Q 5 during the positive half of the AC power source. The current amplifier Q 3 is coupled between the capacitor C 5 of the voltage averaging circuit and the duty cycle capacitor C 6 . More particularly, the duty cycle capacitor C 6 is coupled between a collector and an emitter of the current amplifier Q 3 .

The pulse width modulator circuit of FIG. 2 further includes a rectifying diode D 5 coupled between the voltage averaging circuit and the current amplifier Q 3 . The rectifying diode D 5 is coupled between a first terminal of the capacitor C 5 of the voltage averaging circuit and a base of the current amplifier Q 3 . A second terminal of the capacitor C 5 of the voltage averaging circuit is coupled to a collector of the drive transistor Q 5 through the resistor R 9 .

The pulse width modulator circuit of FIG. 2 also includes a second diode D 4 coupled between the base and the collector of the current amplifier Q 3 . Diode D 4 is provided to protect current amplifier Q 3 from being damaged by an emitter to base voltage breakdown caused by the reverse leakage of diode D 5 . The circuit of FIG. 2 further includes a capacitor C 10 coupled between the base and the collector of the current amplifier Q 3 . Capacitor C 10 is provided to limit or even prevent electrical noise, such as that caused by radio interference, from affecting the operation of the photosensor circuit.

Embodiments of the present invention will now be described with reference to the circuit diagrams of FIGS. 3 and 4 . For purposes of explaining the present invention, the controller circuit of FIGS. 3 and 4 illustrate an autorecloser breaker circuit that may be used, for example, to control AC power distribution to a customer. More particularly, the embodiments of FIGS. 3 and 4 utilize a relay circuit generally corresponding to that described with reference to FIG. 2 , with the photocontrol circuit replaced with a current control circuit. Note that the circuit of FIG. 2 also differs in the coupling of the LINE and NEUTRAL signals (i.e., polarity).

Unlike the SCS autorecloser discussed above, the illustrated embodiments of autoreclosers use an electromagnetic relay, as described with reference to FIG. 2 , instead of a TRIAC. As such, embodiments of the present invention may provide an autorecloser that is more energy efficient. As a result, the circuit may be applied without needing a heat sink and providing an energy cost savings. In addition, cooler operation and a smaller physical size may be provided as well as improved resistance to current surges with a circuit able to operate with higher operating currents. In addition, some embodiments of the present invention are hot pluggable. This may allow different accessories to be swapped in and out with the autorecloser, such as current limiters set at other current levels, shorting caps (to turn off current limiting), and open caps (to turn off power to the customer).

The illustrated embodiments of FIGS. 3 and 4 generally include: a relay and drive circuit, a power circuit, a micro controller, a current sensor (sense) circuit, a comparator circuit, a timer, a logic circuit and an indicator light. The comparator circuit, timer and logic circuit may be implemented in the micro controller. The circuit may also be coupled to a connector (LINE, LOAD, NEUTRAL) and placed in an electrically insulated protective housing (e.g., a weatherproof plastic cover and base connector that may be certified by safety agencies) as will be further described with reference to FIG. 5 .

The embodiments of FIGS. 3 and 4 use a current shunt R 1 for detection of customer energy usage (i.e., as a current sense circuit). The relay K 1 may be opened when the detected energy usage exceeds a reference level. For the embodiments of FIGS. 3 and 4 , the reference level is set by the reference voltage (and current limit) adjustment circuit, including resistors R 15 and R 16 and capacitor C 15 . The illustrated resistor R 16 is a variable resistor, shown as a potentiometer, which may be used to calibrate or shift the reference level.

The micro controller U 1 implements the comparator circuit by comparing the inputs on pins CI− and CI+. The pin GP 2 may be shorted to VSS (negative polarity power supply input, coupled to LINE for the polarity seen in FIGS. 3 and 4 ) to turn current flow on to the relay K 1 (i.e., breaking the circuit to the customer) or set to a high impedance (e.g., set as an input rather than an output pin) to turn off current flow to the relay K 1 to allow normally closed operation (i.e., providing power to the customer by connecting the customer location to the AC power source). In other words, pin GP 2 may be grounded, in which case the base current to transistor Q 5 will stop by shorting the base and emitter of Q 5 through micro controller U 1 , to stop current flow in the coil of the relay K 1 , allowing normally closed operation of the relay with AC power provided to the customer location. When GP 2 is set to high impedance, current will flow to the base of transistor Q 5 to allow regulated current flow through the coil of the relay K 1 , allowing opening of the relay K 1 and cutting off AC power provided to the customer location. It will be understood that the logic would reverse in the case of a normally open relay. It will further be understood that the micro controller may be programmed to provide a reset timer and related logic, such as the delay time before reset, the number of resets allowed and the like depending upon the customer application needs.

In some embodiments the current sense circuit including the current shunt resistor R 1 further includes an anti-aliasing filter circuit R 10 , C 3 coupled to the current shunt R 1 and the CI+ pin of the micro controller U 1 . In addition, in some embodiments, the pin GP 3 of micro controller U 1 is shown as coupled to the LINE reference (used as the ground reference bus in the illustrated embodiments) through a resistor R 6 ′. Resistor R 6 ′ may be used to lower the power supply VDD current used by micro controller U 1 . An indicator lamp LAMP is also used in some embodiments, which may be used to provide a visual indication of the state of the relay. The lamp may be located remote from or local to the circuit, such as on the housing containing the circuit.

Note that the anode of diode D 3 is connected to the pin VDD of micro controller U 1 instead of the pin VSS of micro controller U 1 . The connection to VDD of the power supply provides that the current that flows through D 3 may be used to power the micro controller U 1 in addition to the alternative current path that will now be described.

Embodiments of controller circuits, such as those illustrated in FIGS. 3 and 4 , are provided with a different power (supply) circuit than described with reference to FIGS. 1 and 2 . It is this power circuit that differs between the embodiments of FIGS. 3 and 4 (note that the relay K 1 is also illustrated in a different manner in FIGS. 3 and 4 but the electrical connections are the same in both figures). Referring first to FIG. 3 , power/current may be coupled to the pin VDD of the micro controller U 1 through diode D 3 or through an alternative current path, shown as resistor R 11 . In addition, the diode D 3 , which was directly coupled to the ground reference in the circuit of FIG. 2 , is coupled to the diode D 16 in FIG. 3 . The power supply circuit for the micro controller U 1 in the embodiments of FIG. 3 further includes capacitors C 7 and C 2 . Note that the two parallel capacitors C 7 , C 2 may be replaced by a single capacitor. However, for embodiments using two capacitors, both an electrolytic and a ceramic capacitor may be used, rather than just an electrolytic capacitor, which may provide better filtering of high frequency noise for the power supply circuit.

By providing the alternative current path through resistor R 11 , the operation of the relay circuit D 3 , R 6 , C 10 , D 4 , D 5 , Q 3 , C 6 , C 5 , R 8 , R 9 , D 6 , K 1 , D 7 , R 10 may be largely isolated from the current flow provided to power the micro controller U 1 (e.g., the current flow to the base of transistor Q 5 may be lower, allowing more rapid operation and lower current consumption).

While the power supply circuit of the embodiments of FIG. 3 provides a lower voltage, higher quality power supply for the micro controller U 1 , variations in AC line voltage level and the like may still result in a ten percent variation in the voltage level at the pin VDD. As such, the power supply in the embodiments of FIG. 4 may be used where an even more stable power input is desired. In addition to diodes D 3 , D 16 , resistors R 6 , R 11 and capacitors C 2 , C 7 , the power supply circuit of the embodiments of FIG. 4 further includes diode D 15 . In addition, the resistor R 15 of the reference voltage and current circuit of FIG. 3 is replaced by the combination of series resistors R 15 and R 12 in the embodiments of FIG. 4 to provide for coupling of the diode D 15 therebetween. Note that, in yet further embodiments, diodes D 16 and D 15 may be coupled in series and the voltage input to pin VDD may be drawn from diode D 15 (i.e., may be set to the Zener voltage level of diode D 15 , rather than the Zener voltage level of diode D 16 ).

As described above, the embodiments of FIGS. 3 and 4 include a power circuit coupled to the controller U 1 and to the relay circuit D 3 , R 6 , C 10 , D 4 , D 5 , Q 3 , C 6 , C 5 , R 8 , R 9 , D 6 , K 1 , D 7 , R 10 that is configured to provide a DC power source to the controller U 1 and to the relay circuit D 3 , R 6 , C 10 , D 4 , D 5 , Q 3 , C 6 , C 5 , R 8 , R 9 , D 6 , K 1 , D 7 , R 10 from the AC power source. The controller U 1 is configured to disconnect the AC power source from the customer location when the detected amount of current exceeds the reference level and to reconnect the AC power source to the customer location responsive to detection of a reconnect condition. The reconnect condition may be, for example, expiration of a selected delay time after the AC power source is disconnected from the customer location. In some embodiments, the reconnect condition is expiration of a selected delay time after the AC power source is diconnected from the customer location but only when a total number of resets since a reference time is less than or equal to a maximum number of allowed resets. In such embodiments, no reconnects may be allowed after the total number of resets is greater than the maximum number of allowed resets until some other reset event occurs to reset the total number of resets that are considered to have occurred.

In particular, the power circuit of FIGS. 3 and 4 includes a half-wave rectifier D 7 , R 10 coupled to the AC power source (NEUTRAL in the illustrated embodiments). The power circuit is configured to provide from the half-wave rectifier D 7 , R 10 a first voltage level as the DC power source to the relay circuit D 3 , R 6 , C 10 , D 4 , D 5 , Q 3 , C 6 , C 5 , R 8 , R 9 , D 6 , K 1 , D 7 , R 10 and a second voltage level, lower than the first voltage level, as the DC power source to the controller U 1 .

The AC power source includes three lines (NEUTRAL, LINE, LOAD) and the half-wave rectifier D 7 , R 10 is coupled to a first of the three lines. As discussed above, the power circuit includes a first diode D 3 having a first end connected to the first of the three lines NEUTRAL and a second end connected to a second diode D 16 of the power circuit and the second voltage level, lower than the first voltage level, is taken from the second end. The power circuit illustrated in FIG. 4 further includes a third diode D 15 coupled in series with the first diode D 3 and in parallel with the second diode D 16 but in some embodiments the third diode D 15 coupled in series with the first diode D 3 and the second diode D 16 .

FIG. 5 is an exploded perspective view of an autorecloser circuit with a housing according to some embodiments of the present invention. As shown in the embodiments of FIG. 5 , the autorecloser circuit 100 includes a base 105 and a mating cover 110 that together define a housing for a circuit board 115 .

The circuit board 115 , as illustrated in FIG. 5 , is connected to the base 105 by mounting screws 120 . The circuit board 115 also includes, on an upper surface 117 thereof, circuitry of the autorecloser circuit, such as illustrated in FIG. 3 or 4 , generally illustrated by the various electrical components shown on the circuit board 115 , including a switching device 135 . The switching device 135 is illustrated as a relay in FIG. 1 . The device circuitry of FIG. 1 is configured to control connection of an AC power source to a customer location by activating or deactivating the relay 135 . The relay 135 may, in turn, be coupled through an electrical connector, such as the illustrated 3-pole locking-type connector 150 to the AC power source when inserted in an AC power receptacle so that power to the customer location may be turned on or off responsive to the state of the relay 135 .

The autorecloser circuit 100 of FIG. 5 may be hot pluggable into the AC power receptacle without damaging the autorecloser circuit. The autorecloser circuit 100 may also be one component of a kit that further includes a shorting cap and/or an open cap having a 3-pole locking-type connector 150 like that shown in FIG. 5 that is configured to be inserted in the AC power receptacle.

The foregoing is illustrative of the present invention and is not to be construed as limiting thereof. Although a few exemplary embodiments of this invention have been described, those skilled in the art will readily appreciate that many modifications are possible in the exemplary embodiments without materially departing from the novel teachings and advantages of this invention. Accordingly, all such modifications are intended to be included within the scope of this invention as defined in the claims. In the claims, means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents but also equivalent structures. Therefore, it is to be understood that the foregoing is illustrative of the present invention and is not to be construed as limited to the specific embodiments disclosed, and that modifications to the disclosed embodiments, as well as other embodiments, are intended to be included within the scope of the appended claims. The invention is defined by the following claims, with equivalents of the claims to be included therein.