Circuit interrupter with optical connection

Abstract

Circuit interrupter positioned between supply circuit and load circuit includes fault detection circuit that senses wave forms to the load circuit, fault processing circuit that detects presence of fault and generates fault output signal when fault detected, and control circuit switch connected to fault processing signal output, wherein control circuit switch is opened by presence of fault output signal, thus isolating load circuit from supply circuit. Preferably fault processing circuit and control circuit are optically linked, such that when fault is detected, control circuit switch is opened by optical fault output signal, thus isolating load circuit from the supply circuit. Circuit interrupter may couple another circuit interrupter via power distribution control unit, optionally manageable remotely via automated control interface.

Description

FIELD OF INVENTION

The invention relates to circuit interrupters, and particularly, to optically coupled circuit interrupters.

BACKGROUND OF INVENTION

A conventional circuit interrupter serves to interrupt power connections to electrical loads. However, conventional circuit interrupters, particularly those designed using electro-mechanical relays with air gaps, suffer unreliable operation due to various environmental interferences, for example, from oxidation, dust, dirt and other physical interferences. There is a need, therefore, for an improved circuit interrupter solution characterized by arc-free and fast switching.

Background publications on solid state circuit interrupters include U.S. Pat. No. 4,245,184 wherein a mechanical toggle control switch is included. U.S. Pat. No. 7,633,727 teaches band pass filters cooperating with a current sensor. U.S. Pat. No. 7,948,719 discloses a solid state device and a control for opening the circuit functioning as a protection switch. U.S. Pat. No. 9,774,182 discloses a solid state series switch positioned between a high voltage, direct current bus and a high voltage DC power source wherein the series switch is configured to establish an open circuit upon receiving an electrical signal. Additional background materials are found in U.S. Pat. Nos. 4,245,185; 6,167,329; 6,788,512; 8,718,830; 9,774,182; 6,141,197; U.S.20080204950; U.S.20100091418; U.S.20100156369; U.S.20100244730; U.S.20100320840; U.S.20130066478; U.S.20130253898; U.S.20140085940; U.S.20150097430; U.S.20160294179; and U.S.20170256934; all cited background literature is incorporated herein in its entirety by reference. The literature contains no suggestion or reference to the use of optical coupling in a circuit interrupter.

SUMMARY

In an exemplary embodiment, a circuit interrupter positioned between a supply circuit and a load circuit comprises fault detection and over-current demand circuits for sensing wave forms to the load circuit, a fault processing circuit for detecting presence of faults and generating fault output signals when a fault is detected, and a control circuit switch connected to fault processing signal output, wherein control circuit switch is opened by presence of fault output signal, thus isolating load circuit from supply circuit. Optionally, fault processing circuit and control circuit are optically linked, such that when fault is detected, control circuit switch is opened by optical fault output signal, thus isolating load circuit from the supply circuit. A circuit interrupter may couple with one or more circuit interrupters via power distribution control unit, optionally manageable remotely via automated control interface. In some embodiments a circuit interrupter may be remotely directed to open circuit or close circuit via communication from a power distribution network in communication with an automated control interface.

BRIEF DESCRIPTION OF FIGURES

FIGS. 1A, 1B, and 1C schematically illustrate prior art circuit interrupters.

FIG. 2 schematically illustrates a solid-state circuit interrupter according to one or more aspects of the present invention.

FIG. 3 schematically illustrates a solid-state circuit interrupter according to one or more aspects of the present invention.

FIG. 4 schematically illustrates a solid-state circuit interrupter according to one or more aspects of the present invention.

FIG. 5 schematically illustrates a solid-state circuit interrupter according to one or more aspects of the present invention.

DETAILED DESCRIPTION

A circuit interrupter positioned between a supply circuit and a load circuit includes a fault detection circuit that senses wave forms to the load circuit, a fault processing circuit that detects the presence of a fault and generates a fault output signal when a fault detected, and a control circuit switch connected to the fault processing circuit, wherein the control circuit switch is activated in response to the fault output signal, thus isolating the load circuit from the supply circuit.

In some embodiments, a circuit interrupter is optically linked to a control circuit, such that when a fault is detected, an optical control circuit switch of the circuit interrupter is activated by an optical signal, thus isolating load circuit from the supply circuit.

A circuit interrupter can be coupled to another circuit interrupter via a power distribution control unit, wherein the power distribution control unit may be configured, optionally, to be managed remotely via automated control interface.

FIGS. 1A, 1B, and 1C schematically illustrate various embodiments of the prior art, none of which have an optical coupling. FIG. 2 is one example of a double pole, single throw circuit interrupter. FIG. 3 is one example of a double pole, single throw circuit interrupter with a “pseudo air gap switch” (alternatively referred to as an “Amber crowbar”). FIG. 4 is one example of a single pole, single throw circuit interrupter. FIG. 5 is one example of a double pole, double throw circuit interrupter.

As used herein, a fault detection circuit sensing waveforms includes the ability to sense over-current conditions, over-voltage conditions, including ground-fault and arc-fault conditions, and then signal which condition is faulting. In addition, when the control circuit switch is opened by the presence of a fault processing signal output thus isolating the load circuit from the supply circuit in some embodiments the control circuit is not isolated from the supply circuit. In the embodiments where a constant optical signal is required, the control circuit is not isolated from the supply circuit when the optical signal is not present. One knowledgeable in the art understands the need for and why a lock-out/tag-out capability is required.

FIG. 1A schematically illustrates a simple power controller. In this art, power is controlled by the controller 110 which controls a TRIAC 105. When released by the source 100, the controller 110 may allow the power through by activating the TRIAC 105 or not, thus allowing power to flow to load 115 or not.

FIG. 1B schematically illustrates a circuit interrupter in which the controller 110 controls the flow of electricity by controlling two solid state bipolar junction transistors 135 and 140 through a connection to the base terminals of the bipolar junction transistors 135 and 140. These two power BJT's 135 and 140 allow for the power from source 100 to flow through them to power the load circuit 115. Each BJT 135 and 140 has a diode connected in parallel with it, wherein the BJT 135 is connected in parallel with diode 125, and the BJT 140 is connected in parallel with diode 130.

FIG. 1C schematically illustrates a circuit interrupter which utilizes two power MOSFETs 145 and 150. Here, the power flows from the source 100 through the MOSFET 145 when the controller turns the MOSFET 145 on and the wave is in the positive part of its cycle. The wave then moves through the diode 130 and the power is then transferred to the load 115. In the negative part of the power cycle, the controller 110 turns the MOSFET 150 on so that power will flow through the MOSFET 150 and the diode 125. The diodes 125 and 130 in FIG. 1C represent internal parasitic diodes of the MOSFETs 145 and 150, respectively, and are illustrated to show functionality. Diodes may also be physically added, but doing so is unneeded.

FIG. 2 schematically illustrates an exemplary embodiment of a Double Pole Single Throw circuit interrupter. FIG. 2 illustrates an AC source 200, two power MOSFETs 220 and 250 which are connected to respective controllers 230 and 240, a load 270, and two diodes 210 and 260 which represent internal parasitic diodes of the MOSFETs 220 and 250, respectively.

The embodiment features two controllers 230 and 240 which control the configuration of the circuit on either the positive or negative part of the wave emanating from the power source 200. On the positive part of the wave, the controller 230 sends a signal to the gate of the power MOSFET 220 turning the MOSFET 220 on. The wave travels through the MOSFET 220, through the load circuit 270 and returns to the source through the diode 260. On the negative part of the wave, the controller 240 turns the MOSFET 250 on through its gate. The wave then travels through the MOSFET 250, through the load circuit 270, and returns to the source 200 through the diode 210. FIG. 2 illustrates a method to greatly reduce the current flowing to the load but does not reduce the current flowing to load to 0. A true air gap circuit by definition would reduce the current to load to 0, therefore there is a need for improvement to the double pole single throw circuit.

FIG. 3 schematically illustrates a solid-state circuit interrupter which is similar to FIG. 2, but which further includes a pseudo airgap switch circuit (or the “Amber Crowbar”) which is placed between the load and the double pole single throw circuit. The basic function of the pseudo airgap switch circuit is to short (or shunt) the load circuit 365 when the double pole single throw circuit is off, thus allowing any signal to bypass the load circuit 365 and protecting the load circuit 365 by reducing the current (e.g., leakage current) to the load to zero when the double pole single throw circuit is off. This improvement makes the solid-state power device have a true airgap without the introduction of electromechanical devices. The pseudo airgap switch circuit comprises a controller 355 which controls two power MOSFETs 340 and 360. When a problematic wave seeks to enter the load circuit, the “Amber Crowbar” circuit activates. On the positive wave cycle, the MOSFET 340 is activated by the controller 355. The wave passes through the MOSFET 340 and diode 350 and returns to the source 300 safely avoiding the load circuit 365. On the negative cycle, the MOSFET 360 is activated by the controller 355. The wave passes through the MOSFET 360 and diode 345 and returns to the source 300 safely avoiding the load circuit 365. As in other embodiments discussed herein, the diodes 345 and 350 represent internal parasitic diodes of the respective MOSFETs 340 and 360, but can include actual diode components, although doing so is redundant.

In some embodiments, a circuit interrupter is positioned between a supply circuit and a load circuit comprises a fault detection circuit sensing wave forms to the load circuit; a fault processing circuit for detecting the presence of a fault and generating a fault output signal when a fault is detected; and a control circuit switch connected to the fault processing signal output wherein the control circuit switch is opened by the presence of the fault output signal thus isolating the load circuit from the supply circuit; optionally a circuit interrupter has a fault processing circuit and the control circuit optically linked such that when a fault is detected the control circuit switch is opened by the optical fault output signal thus isolating the load circuit from the supply circuit; optionally a circuit interrupter is coupled to another circuit interrupter via a power distribution control unit; optionally a circuit interrupter comprises a power distribution control unit manageable remotely via an automated control interface.

In some embodiments a circuit interrupter positioned between a supply circuit and a load circuit comprises a fault detection circuit sensing wave forms to the load circuit; a fault processing circuit for detecting the presence of a fault and generating an optical fault output signal when a fault is detected; and a control circuit switch optically connected to the fault processing signal output wherein the switch is opened by the presence of the fault output signal isolating the load circuit from the supply circuit; optionally, a circuit interrupter is coupled to another circuit interrupter via a power distribution control unit; optionally, a circuit interrupter is coupled to a power distribution control unit manageable remotely via an automated control interface.

In some embodiments a circuit interrupter method comprises the steps of sensing by a fault detection circuit wave forms to a load circuit; of detecting by a fault processing circuit presence of a fault; and of generating by the fault processing circuit an optical fault output signal when a fault is detected; wherein a control circuit switch is optically connected to the fault processing signal output, such that the switch is opened by the presence of the fault output signal isolating the load circuit from a supply circuit; optionally, the step of coupling to another circuit interrupter via a power distribution control unit; optionally, the power distribution control unit is manageable remotely via an automated control interface.

In some embodiments a circuit interrupter positioned between a supply circuit and a load circuit comprises a fault detection circuit sensing wave forms to the load circuit; a fault processing circuit for detecting the presence of a fault and generating a fault output signal when a fault is detected; and wherein the fault processing circuit and the control circuit must be optically linked for continuous operation such that when a fault is detected the control circuit switch is opened by the absence of an optical signal thus isolating the load circuit from the supply circuit; optionally, a circuit interrupter comprises a fault processing circuit and control circuit optically linked but physically separated from each other such that a physical object may be inserted between them blocking the optical link; optionally, a circuit interrupter comprises a physical object is a portion of a lock-out/tag-out mechanism that is configured to render the circuit interrupter in a state wherein current can not flow from the supply circuit to the load circuit.

In some embodiments an apparatus comprises a plurality of circuit interrupters, each positioned between a supply circuit and a load circuit wherein the apparatus comprises a power distribution control unit and is manageable remotely via an automated control interface.

FIG. 4 schematically illustrates a solid-state circuit interrupter according to an exemplary embodiment. For example, FIG. 4 illustrates an exemplary embodiment for implementing a controller as shown in the embodiments of FIGS. 2 and 3. In the exemplary embodiment of FIG. 4, the control block comprises a source connection 400, a load 460, MOSFETS 425 and 455, internal parasitic diodes 475 and 480 of the MOSFETs 425 and 455, respectively, two diodes 405 and 420, a voltage reference that is generated by a Zener diode 470 and a capacitor 430. Additionally, there are 4 resistors 410, 415, 465 and 435. An operational amplifier 440 is connected to a BJT 445 which is mirrored to an optically controlled phototransistor 450 all of which control the operation of the MOSFET 425 and MOSFET 455. FIG. 5 schematically illustrates a solid-state circuit interrupter according to another exemplary embodiment. For example, FIG. 5 illustrates another exemplary embodiment for implementing a controller as shown in the embodiments of FIGS. 2 and 3. The embodiment of FIG. 5 comprises 4 diodes 510, 520, 570 and 597, two MOSFETs 525 and 575, a BJT 540, and a phototransistor 545. The embodiment of FIG. 5 further comprises two Zener diodes 555 and 590 that are connected in parallel with respective capacitors 560 and 585, to provide clamping circuits that generate voltage references to drive the MOSFETs 525 and 575. Finally, there is an operational amplifier 535 which functions as a controller for the BJT 540. Additionally, one embodiment may include a programable chip inside of the controller for further control over the power functions.

The controller's main function is to convert AC power to DC by using of switching. This process starts with the configuration of the controller by applying a photo source to phototransistor 545. The optical signal (denoted by the arrows directed to the phototransistor 545) can enter through a device such as a connected fiber optics cable, but other methods and devices work as well. Optionally, the phototransistor 545 can be replaced by a more typical power BJT, but the preferred embodiment includes the phototransistor 545.

When turned on, the optical transistor 545 stays on until the rest of the controller is set. Essentially, the phototransistor 545 begins an initialization state for a few cycles of applied AC power around a few hundred milliseconds, but this can be tuned for faster or slower startup speeds. With the addition of an optional control block, the optical transistor 545 can be used as a means for control of the controller or other added function with use of control blocks.

This process starts with the AC source 500 emitting power. On the positive part of the cycle, the wave travels to the first node marked 505. Then, the wave enters the diode 510 and passes over resistor 515. Next, the wave begins to charge the capacitor 585 and Zener diode 590 pair after passing over resistor 580. This pair functions as a gate driver which will turn the power MOSFET 575 on for the next cycle. On the negative part of the first cycle, the wave passes over the diode 570 and the resistor 565 to charge the Zener diode 555 and the capacitor 560 pair, which like the other pair functions as a gate source driver to drive the power MOSFET 525. Additionally, this negative part of the wave enters the comparator 535 serving as the V− for proper comparator function.

The next cycle begins with each of the power MOSFETS 525 and 575 turned on. The positive cycle of the wave is first. Here, the wave passes through the MOSFET 525 and then across the resistor 530. The voltage across the resistor 530 is measured by the comparator 535. If the voltage closest to the MOSFET is less than the voltage of that at the rightmost end of the resistor 530, the comparator 535 turns on and effectively clamps the circuit by turning on the BJT 540, resulting in shunting the current away from the load and deactivating the MOSFET 525. If the wave is not shunted, then it begins entering the load 595. The wave then exits the load 595 and enters the anode of the diode 597 and exits the cathode and returns to the source 500.

On the negative part of the wave, the wave passes through the MOSFET 575, enters the load 595, and then exits it. Then, the wave enters the anode of diode 520 exits the cathode and returns to the source.

The overall function of the circuit allows for controlled delivery of power to the load 595 with control along the way by means of the operational amplifier 535 and the phototransistor 545.

Foregoing descriptions of specific embodiments of the invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed. Modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to explain the principles and the application of the invention, thereby enabling others skilled in the art to utilize the invention in its various embodiments and modifications according to the particular purpose contemplated. The scope of the invention is intended to be defined by the claims appended hereto and their equivalents.

Claims

1. A circuit interrupter comprising: a solid-state switch serially connected between a line input terminal and a load output terminal of the circuit interrupter, and configured to be placed in one of (i) a switched-on state to provide an electrical connection in an electrical path between the line input terminal and the load output terminal, and (ii) a switched-off state;switch control circuitry configured to control the solid-state switch, wherein the switch control circuitry comprises:a driver circuit configured to generate a drive voltage using current drawn from an input power source applied to the line input terminal of the circuit interrupter, wherein the drive voltage is applied to a control input of the solid-state switch to place the solid-state switch in the switched-on state;a fault detection circuit configured to (i) sense a voltage level across a sense resistor which is serially connected with the solid-state switch in the electrical path between the line input terminal and the load output terminal and (ii) generate a fault output signal in response to detecting a fault condition based on the sensed voltage level across the sense resistor;a control switch connected to the fault detection circuit and configured to place the solid-state switch in the switched-off state, in response to the fault output signal generated by the fault detection circuit; andan optical switch configured to place the solid-state switch in the switched-off state, in response to an optical control signal applied to the optical switch.

2. The circuit interrupter of claim 1, wherein said circuit interrupter is coupled to at least one other circuit interrupter via a power distribution control unit.

3. The circuit interrupter of claim 2, wherein the power distribution control unit is configured to be managed remotely via an automated control interface.

4. The circuit interrupter of claim 1, wherein the solid-state switch comprises a first MOSFET switch and a second MOSFET switch serially connected between the line input terminal and the load output terminal of the circuit interrupter, wherein the sense resistor is serially connected between the first and second MOSFET switches.

5. The circuit interrupter of claim 1, wherein the driver circuit comprises a voltage clamping circuit configured to generate the drive voltage to drive the solid-state switch.

6. The circuit interrupter of claim 5, wherein the clamping circuit comprises a capacitor and a Zener diode connected in parallel.

7. The circuit interrupter of claim 1, wherein the fault detection circuit comprises an operational amplifier having first and second input terminals connected across the sense resistor, and an output terminal connected to the control switch.

8. The circuit interrupter of claim 7, wherein the control switch comprises a bipolar junction transistor device having a base terminal connected to the output terminal of the operational amplifier.

9. The circuit interrupter of claim 1, wherein the optical switch comprises a phototransistor device.

10. The circuit interrupter of claim 1, further comprising an isolation circuit which is configured to shunt leakage current away from a load circuit connected to the circuit interrupter, when the solid-state switch is in the switched-off state.

11. A method, comprising: controlling a solid-state switch, which is serially connected between a line input terminal and a load output terminal of a circuit interrupter, to place the solid-state switch in one of (i) a switched-on state to provide an electrical connection in an electrical path between the line input terminal and the load output terminal of the circuit interrupter, and (ii) a switched-off state;wherein controlling the solid-state switch comprises: generating a drive voltage using current drawn from an input power source applied to the line input terminal of the circuit interrupter;applying the drive voltage to a control input of the solid-state switch to place the solid-state switch in the switched-on state;sensing a voltage level across a sense resistor which is serially connected with the solid-state switch in the electrical path between the line input terminal and the load output terminal;generating a fault output signal in response to detecting a fault condition based on the sensed voltage level across the sense resistor; andplacing the solid-state switch in the switched-off state, in response to generating the fault output signal; andwherein controlling the solid switch further comprises: applying an optical control signal to activate an optical switch of the circuit interrupter; andplacing the solid-state switch in the switched-off state, in response to the activation of the optical switch.

12. The method of claim 11, wherein generating the drive voltage using current drawn from the input power source applied to the line input terminal of the circuit interrupter comprises charging a clamping circuit to generate the drive voltage to drive the solid-state switch.

13. The method of claim 11, wherein: sensing the voltage level across the sense resistor comprises applying the sensed voltage level across first and second input terminals of an operational amplifier; andgenerating the fault output signal comprises the operational amplifier generating the fault output signal and outputting the fault output signal, in response to detecting a fault condition based on the sensed voltage level across the sense resistor.

14. The method of claim 11, wherein placing the solid-state switch in the switched-off state, in response to generating the fault output signal, comprises activating a control switch in response to the fault output signal, wherein activation of the control switch results in deactivation of the solid-state switch.

15. The method of claim 11, further comprising activating an isolation circuit to shunt leakage current away from a load circuit connected to the circuit interrupter, in response to solid-state switch being placed in the switched-off state.

16. A circuit interrupter, comprising: a first solid-state switch serially connected between a first line input terminal and a first load output terminal of the circuit interrupter, and configured to be placed in one of (i) a switched-on state to provide an electrical connection in a first electrical path between the first line input terminal and the first load output terminal, and (ii) a switched-off state;a second solid-state switch serially connected between a second line input terminal and a second load output terminal of the circuit interrupter, and configured to be placed in one of (i) a switched-on state to provide an electrical connection in a second electrical path between the second line input terminal and the second load output terminal, and (ii) a switched-off state;switch control circuitry configured to control the first and second solid-state switches, wherein the switch control circuitry comprises:a first driver circuit configured to generate a first drive voltage using current drawn from an input power source applied to the first and second line input terminals of the circuit interrupter, wherein the first drive voltage is applied to a control input of the first solid-state switch to place the first solid-state switch in the switched-on state;a second driver circuit configured to generate a second drive voltage using current drawn from the input power source applied to the first and second line input terminals of the circuit interrupter, wherein the second drive voltage is applied to a control input of the second solid-state switch to place the second solid-state switch in the switched-on state;a fault detection circuit configured to (i) sense a voltage level across a sense resistor which is serially connected with the first solid-state switch in the first electrical path between the first line input terminal and the first load output terminal and (ii) generate a fault output signal in response to detecting a fault condition based on the sensed voltage level across the sense resistor;a control switch connected to the fault detection circuit and configured to place the solid-state switch in the switched-off state, in response to the fault output signal generated by the fault detection circuit; andan optical switch configured to place the first solid-state switch in the switched-off state, in response to an optical control signal applied to the optical switch.

17. The circuit interrupter of claim 16, wherein the fault detection circuit comprises an operational amplifier having first and second input terminals connected across the sense resistor, and an output terminal connected to the control switch.

18. The circuit interrupter of claim 17, wherein the control switch comprises a bipolar junction transistor device having a base terminal connected to the output terminal of the operational amplifier.

19. The circuit interrupter of claim 16, wherein the optical switch comprises a phototransistor device.

20. The circuit interrupter of claim 16, further comprising an isolation circuit which is configured to shunt leakage current away from a load circuit connected to the circuit interrupter, when at least the first solid-state switch is in the switched-off state.