Description:TECHNICAL FIELD
[0001] The present disclosure relates, in general, to the field of protection circuits. More particularly, the present disclosure provides a circuit breaker for protecting an electrical device from leakage current and overvoltage.

BACKGROUND
[0002] Leakage current protection is important for human and fire protection. It typically ensures that a user does not experience an electric shock for greater than a stipulated time, therefore ensuring the experienced shock is not fatal.
[0003] Due to poor power quality, electrical equipment operates in over voltage condition due to fluctuations in system voltage. Eventually such operating voltages lead to damage of the electrical equipment. Sustaining Overvoltage for a longer period will lead to damage of metal-oxide varistor (MOV) and fire accidents. The detection of overvoltage along with leakage current detection in the electrical equipment will ensure both human protection and improve fire protection.
[0004] Some protective circuit solutions provide a residual current protection device for Leakage current detection. The residual current protection device comprises a leakage detection circuit, a trigger circuit and a voltage stabilizing circuit. The leakage detection circuit is configured to output a leakage protection trigger signal when a leakage current occurs on a power supply line. The trigger circuit is connected to the leakage detection circuit and outputs a trip signal in response to the leakage protection trigger signal. Further, the voltage stabilizing circuit provides a stable power supply voltage to the leakage detection circuit. However, the patent document does not provide any solution for overvoltage protection making equipment vulnerable to failure and more prone to fire accidents.
[0005] Another solution provides a protection circuit intended to be connected between an electrical energy source and an overvoltage-sensitive device. A current limiting circuit and a current monitoring circuit are connected in series, a reference voltage generator circuit delivering a reference voltage, and a balancing circuit is intended to control the current monitoring circuit so that the voltage at a point of connection between the current limiting circuit and the current monitoring circuit is substantially equal to the reference voltage. An electrical measurement or power supply device including at least one such overvoltage protection circuit. However, the patent document describes circuit for Overvoltage protection but nowhere describes leakage current protection, thereby leading the user vulnerable to fatal electric shock and chances of fire due to leakage current.
[0006] Yet another solution provides an integral type protection electric leakage circuit breaker circuit. The circuit includes an integrated chip (U1), trip circuit, a power supply circuit for the integrated chip (U1) provides a direct current (DC) voltage, an electric leakage detection circuit for gathering the electric leakage signal, a cross under-voltage circuit for gathering overvoltage signal and under -voltage signal, an overload protection circuit for gathering overload circuit signal, the integrated chip (U1) can judge electric leakage detection circuit, cross the signal that under -voltage circuit and overload protection circuit gathered, and can cut off the major loop through trip circuit, it includes diode VD6 and parallelly connected excessive pressure return circuit and under-voltage return circuit to cross under-voltage circuit, mains voltage inserts excessive pressure return circuit and under -voltage return circuit respectively behind diode VD6 half -wave rectification, overvoltage signal that excessive pressure return circuit and under -voltage return circuit will be gathered and under -voltage signal are inputted respectively to two pins of the integrated chip (U1). In this case, the combined circuit provides protection from leakage current and overvoltage. However, to achieve the combined protections, a specialized IC (chip) is used which takes inputs from Leakage detection circuit and over voltage circuits separately and provides trip command to Silicon controlled rectifier (SCR). This type of arrangement increases the complexity of design due to customized Integrated chip (IC).
[0007] While the conventional art may disclose protective circuit solutions, however, they fail to address the problem of increased leakage current and overvoltage in an electric device. There is, therefore, a need of an improved circuit breaker for leakage current protection and overvoltage protection that is offering human protection, equipment protection, enhanced fire protection and eliminates the need of a customized IC.

OBJECTS OF THE PRESENT DISCLOSURE
[0008] An object of the present disclosure relates, in general, to circuit breaker and more specifically, relates to a circuit breaker for protecting an electrical device from leakage current and overvoltage.
[0009] Another object of the present disclosure is to provide a circuit breaker offering human protection, equipment protection and enhanced fire protection.
[0010] Another object of the present disclosure is to provide a protection circuit for a circuit breaker that eliminates need of customised integrated chip (IC), thereby providing economical design of the integrated circuit.
[0011] Another object of the present disclosure is to provide a protection circuit for a circuit breaker sharing a common actuator, thereby reducing the size of the circuit.

SUMMARY
[0012] The present disclosure relates, in general, to the field of protection circuits. In particular, the present disclosure provides a circuit breaker for protecting an electrical device from leakage current and overvoltage.
[0013] An aspect of the present disclosure pertains a circuit breaker to detect leakage current and overvoltage in electrical devices. The circuit breaker for protecting an electrical device from leakage current and overvoltage, the circuit breaker includes a protection circuit for detecting leakage current and overvoltage through the electrical device and/or the circuit breaker. The protection circuit includes a leakage current detection circuit and an overvoltage detection circuit, where the protection circuit is configured to trip the circuit breaker when the leakage current detection circuit detects a rise in real-time current flowing through the circuit breaker being greater than a pre-defined threshold value, or the overvoltage detection circuit detects a real-time voltage across the circuit breaker being greater than a pre-defined breakdown voltage value.
[0014] In an aspect, the leakage current detection circuit may include an electromagnetic coil, a power resistor, a controller, a first set of terminals, a current transformer electrically coupled with the first set of terminals, a network of resistors and a network of capacitors.
[0015] In an aspect, when the current transformer may detect a leakage current, the current transformer may produce a voltage across a secondary winding of the current transformer that is inputted to the controller to measure the produced voltage.
[0016] In an aspect, the controller may compare the measured voltage with the pre-defined threshold value, and in case the measured voltage is higher than the pre-defined threshold value, the controller may produce a high current at at least one pin of the controller connected to a switching unit and may actuate the switching unit.
[0017] In an aspect, the switching unit may be connected in series with the electromagnetic coil, the actuated switching unit may increase the current through the electromagnetic coil and may provide a fault or trip signal associated with leakage current to the circuit breaker.
[0018] In an aspect, the overvoltage detection circuit may include a voltage bridge, a semi-conductor diode connected in series with the voltage bridge and to a gate terminal of the switching unit.
[0019] In an aspect, the overvoltage detection circuit may be connected across a phase terminal and a neutral terminal for power supply.
[0020] In an aspect, when a voltage across the Phase and Neutral terminals may be in an overvoltage range, the voltage divider may be calibrated in a manner that the voltage across the semi-conductor diode is greater than the pre-defined breakdown voltage value, that enables the current to flow through the semi-conductor diode and may actuate the switching unit that is electrically coupled to the semi-conductor diode.
[0021] In an aspect, the actuated switching unit may increase the current through the electromagnetic coil and may provide a fault or trip signal associated with overvoltage to the circuit breaker.
[0022] In an aspect, a test circuit may be electrically coupled to the leakage current detection circuit. The test circuit may include a second set of terminals looped through a primary of the current transformer, one or more second resistors and a switch. The one or more resistors are arranged such that when the switch is turned ON, a calibrated leakage current may flow through the primary of the current transformer and may generate an artificial leakage fault and the calibrated leakage current may be detected by the leakage current detection circuit that may activate the electromagnetic coil to provide a fault/ trip command.
[0023] Various objects, features, aspects, and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments, along with the accompanying drawing figures in which like numerals represent like components.

BRIEF DESCRIPTION OF THE DRAWINGS
[0024] The following drawings form part of the present specification and are included to further illustrate aspects of the present disclosure. The disclosure may be better understood by reference to the drawings in combination with the detailed description of the specific embodiments presented herein.
[0025] FIG. 1 illustrates a block diagram of a circuit breaker for protecting an electrical device from leakage current and overvoltage, in accordance with an embodiment of the present disclosure.
[0026] FIG. 2 illustrates a protection circuit for the circuit breaker for protecting an electrical device from leakage current and overvoltage, the integrated circuit, in accordance with an embodiment of the present disclosure.
[0027] FIG. 3 illustrates a leakage current detection circuit of the protection circuit, in accordance with an embodiment of the present disclosure.
[0028] FIG. 4 illustrates a test circuit of the protection circuit, in accordance with an embodiment of the present disclosure.
[0029] FIG. 5 illustrates an overvoltage detection circuit of the protection circuit, in accordance with an embodiment of the present invention.

DETAILED DESCRIPTION
[0030] The following is a detailed description of embodiments of the disclosure depicted in the accompanying drawings. The embodiments are in such detail as to clearly communicate the disclosure. If the specification states a component or feature “may”, “can”, “could”, or “might” be included or have a characteristic, that particular component or feature is not required to be included or have the characteristic.
[0031] As used in the description herein and throughout the claims that follow, the meaning of “a,” “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise.
[0032] The present disclosure relates, in general, to the field of protection circuits. Specifically, the present disclosure provides a circuit breaker for protecting an electrical device from leakage current and overvoltage.
[0033] In an embodiment of the present disclosure, a combined electronic circuit for leakage current protection and overvoltage protection is disclosed. Such electronic protection circuit may usually involve designing a lean or a combined integrated circuit (IC) to achieve the required protective function of both leakage protection and overvoltage protection.
[0034] The combined circuit can provide an actuation command to an electromagnetic coil of a core balanced current transformer (CBCT) to trip a circuit breaker in situations like current leakage or overvoltage conditions.
[0035] Further, an output signal of an overvoltage release may be used to provide a trigger signal to the electronic circuit, which in turn may actuate electromagnetic coil to trip the circuit breaker. In case of a leakage circuit, leakage is sensed by the CBCT which in turn inputs this measurement to a leakage detector IC. The leakage detector IC may compare the value of leakage to a set value and if the value is over a set threshold, it may further give the trigger signal to actuate the electromagnetic coil to trip the circuit breaker.
[0036] The present disclosure elaborates upon a circuit breaker for protecting an electrical device from leakage current and overvoltage. The circuit breaker includes a protection circuit for detecting leakage current and overvoltage through the electrical device and/or the circuit breaker. The protection circuit includes a leakage current detection circuit and an overvoltage detection circuit, where the protection circuit is configured to trip the circuit breaker when the leakage current detection circuit detects a rise in real-time current flowing through the circuit breaker being greater than a pre-defined threshold value, or the overvoltage detection circuit detects a real-time voltage across the circuit breaker being greater than a pre-defined breakdown voltage value.
[0037] In an embodiment, the leakage current detection circuit may include an electromagnetic coil, a power resistor, a controller, a first set of terminals, a current transformer electrically coupled with the first set of terminals, a network of resistors and a network of capacitors.
[0038] In an embodiment, when the current transformer may detect a leakage current, the current transformer may produce a voltage across a secondary winding of the current transformer that is inputted to the controller to measure the produced voltage.
[0039] In an embodiment, the controller may compare the measured voltage with the pre-defined threshold value, and in case the measured voltage is higher than the pre-defined threshold value, the controller may produce a high current at at one least pin of the controller connected to a switching unit and may actuate the switching unit.
[0040] In an embodiment, the switching unit may be connected in series with the electromagnetic coil, the actuated switching unit may increase the current through the electromagnetic coil and may provide a fault or trip signal associated with leakage current to the circuit breaker.
[0041] In an embodiment, the overvoltage detection circuit may include a voltage bridge, a semi-conductor diode connected in series with the voltage bridge and to a gate terminal of the switching unit.
[0042] In an embodiment, the overvoltage detection circuit may be connected across a phase terminal and a neutral terminal for power supply.
[0043] In an embodiment, when a voltage across the Phase and Neutral terminals may be in an overvoltage range, the voltage divider may be calibrated in a manner that the voltage across the semi-conductor diode is greater than the pre-defined breakdown voltage value, that enables the current to flow through the semi-conductor diode and may actuate the switching unit that is electrically coupled to the semi-conductor diode.
[0044] In an embodiment, the actuated switching unit may increase the current through the electromagnetic coil and may provide a fault or trip signal associated with overvoltage to the circuit breaker.
[0045] In an embodiment, a test circuit may be electrically coupled to the leakage current detection circuit. The test circuit may include a second set of terminals looped through a primary of the current transformer, one or more second resistors and a switch. The one or more resistors are arranged such that when the switch is turned ON, a calibrated leakage current may flow through the primary of the current transformer and may generate an artificial leakage fault and the calibrated leakage current may be detected by the leakage current detection circuit that may activate the electromagnetic coil to provide a fault/ trip command.
[0046] The present disclosure can be described in enabling detail in the following examples, which may represent more than one embodiment of the present disclosure.
[0047] FIG. 1 illustrates a block diagram of a circuit breaker 100 for protecting an electrical device from leakage current and overvoltage, in accordance with an embodiment of the present disclosure.
[0048] Referring to FIG. 1, the circuit breaker 100 includes a protection circuit 102 for detecting leakage current and overvoltage through the electrical device and/or the circuit breaker 100. The protection circuit 102 includes a leakage current detection circuit 104 and an overvoltage detection circuit 106. The protection circuit 102 is configured to trip the circuit breaker when the leakage current detection circuit 104 detects a rise in real-time current flowing through the circuit breaker 100 being greater than a pre-defined threshold value, or the overvoltage detection circuit 106 detects a real-time voltage across the circuit breaker 100 being greater than a pre-defined breakdown voltage value.
[0049] Further, a test circuit 108 may be electrically coupled to the leakage current detection circuit 104 to test the leakage current detection circuit 104 by actuating a switch SW1 configured in the test circuit 108.
[0050] FIG. 2 illustrates a protection circuit 102 for the circuit breaker 100 for protecting an electrical device from leakage current and overvoltage, the integrated circuit, in accordance with an embodiment of the present disclosure.
[0051] Referring to FIG. 2, the protection circuit 102 consists of Phase (P) and Neutral (N) terminals for powering up the protection circuit 102. The protection circuit 102 includes a leakage current detection circuit 104 and an overvoltage detection circuit 106, where the protection circuit 102 is configured to trip the circuit breaker 100 when the leakage current detection circuit 104 detects a rise in real-time current flowing through the circuit breaker 100 being greater than a pre-defined threshold value, or the overvoltage detection circuit 106 detects a real-time voltage across the circuit breaker 100 being greater than a pre-defined breakdown voltage value.
[0052] FIG. 3 illustrates a leakage current detection circuit 104 of the protection circuit 102, in accordance with an embodiment of the present disclosure.
[0053] Referring to FIG. 3, the leakage current detection circuit 104 may include an electromagnetic coil 301, a power resistor R4, a controller U1, a first set of terminals (T1, T3), a current transformer 302 electrically coupled with the first set of terminals, a network of resistors and a network of capacitors. The network of resistors may include but not limited to resistors RF1, R3 and R2 and the network of capacitors may include but not limited to capacitors C12, C10 & C11. The controller U1 is powered up by a phase (P) and a neutral supply (N) and the power resistor R4 is used to set the current level required to power up the controller U1 according to voltage. The controller U1 may be selected from but not limited to microcontroller, microprocessor, integrated chips (IC) and the like. The controller U1 may also be referred as a ground fault detector integrated chip (IC). A secondary windings of the current transformer 302 is connected to the first set of terminals T1 and T2 which are in turn connected with the ground fault detector integrated chip (U1) through the network of Resistors (RF1, R3 & R2) and the networks of Capacitors (C12, C10 & C11) to condition the secondary voltage of the current transformer 302.
[0054] Further, a switching unit U2 is connected in series with the electromagnetic coil. In normal condition, the U2 is in OFF condition and a current through the electromagnetic coil 301 is almost zero and there is no trip command provided. In fault condition, the switching unit U2 is switched ON and the current through the electromagnetic coil 301 increases drastically providing a fault/trip command to the current breaker 100.
[0055] In addition, when a primary of the current transformer 302 detects a current imbalance or Leakage current, the primary of the current transformer 302 produces a voltage across the secondary winding. The produced voltage acts as an input for the controller U1 and injected across one or more pins (pin 1 and pin 2) of the IC (U1). The ground fault detector IC U1 measures the conditioned voltage across the secondary of the current transformer 302 and compares it with a pre-defined threshold value. If the measured voltage value is greater than the pre-defined threshold value, the ground fault detector IC U1 makes high current at the at least one pin (Pin 7) which is connected with a gate of the switching unit U2. This action switches on the switching unit U2, thereby increasing the current through electromagnetic coil 301 and providing a Fault/Trip command to the current breaker 100. Thus, ensuring timely detection of the leakage current to ensure protection to a user and prevention of fire accidents.
[0056] In an embodiment, the switching unit U1 may include a Silicon-Controlled Rectifier (SCR).
[0057] In an embodiment, the electromagnetic coil 301 may be selected from group consisting of but not limited to alternate current (AC)-Laminated Solenoid, Direct Current (DC)-C Frame Solenoid, DC- D Frame Solenoid, Linear Solenoid and Rotary Solenoid. Further, the current transformer may be a coil balance current transformer (CBCT).
[0058] FIG. 4 illustrates a test circuit 108 of the protection circuit 102, in accordance with an embodiment of the present disclosure.
[0059] Referring to FIG. 4, the test circuit 108 is electrically coupled to the leakage current detection circuit 104. The test circuit 108 may include a second set of terminals T3, T4 looped through the primary of the current transformer 302, one or more second resistors and a switch SW1. The second set of terminals may include terminal T4 and terminal T3. The one or more second resistors may include resistors “R2”, “R8” and “R9”. The one or more resistors “R2”, “R8”, and “R9” are arranged such that when the switch SW1 is turned ON, a calibrated leakage current flows through the primary of the current transformer 302 and generates an artificial leakage fault and the calibrated leakage current is detected by the leakage current detection circuit 104 that activates the electromagnetic coil 301 to provide a fault/ trip command. The test circuit 108 enables the user to test the leakage current detection circuit 104 by actuating the Switch SW1.
[0060] FIG. 5 illustrates an overvoltage detection circuit 106 of the protection circuit 102, in accordance with an embodiment of the present invention.
[0061] Referring to FIG. 5, the overvoltage detection circuit 106 is connected across a phase (P) terminal and a neutral (N) terminal for power supply. The overvoltage detection circuit 106 may include a voltage bridge 501, a semi-conductor diode DZ1 connected in series with the voltage bridge 501 and to a gate terminal of the switching unit U2.
[0062] In an embodiment, the voltage bridge may include one or more third resistors. The one or more third resistors can include resistors “R6”, “R5” and “R1”. In an embodiment, the voltage bridge 501 may be selected from but not limited potential divider bridge, Wheatstone bridge and the like.
[0063] Further, when the voltage across the Phase (P) and the Neutral (N) terminals is in normal range, for example 240V voltage, the voltage bridge 501 is calibrated in such a way that a voltage across the DZ1 is lower than a pre-defined breakdown voltage value. Whenever voltage across the Phase (P) and the Neutral (N) terminals moves into an overvoltage range, for example 270V, the voltage bridge 501 is calibrated in such a way that the voltage across the semi-conductor diode DZ1 is greater than the pre-defined breakdown voltage value. This enables the current to conduct across the semi-conductor diode DZ1 which provides a trip command directly to the switching unit U2 as the semi-conductor diode DZ1 is connected to the Gate terminal of the switching unit U2. The trip command switches ON the switching unit U2 by increasing the current through the electromagnetic coil/solenoid 301 and providing a Fault/Trip command to the current breaker 100, thereby ensuring overvoltage protection.
[0064] In an embodiment, the semi-conductor diode DZ1 can be selected from but not limited to Zener diode (breakdown diodes), variable capacitance diode, switching diode and the like.
[0065] It can be clearly seen from above explanations that the detection for leakage current detection and Overvoltage detection are exclusive to each other. The trip signal associated with overvoltage is directly provided to the switching unit U2 and is not routed through the integrated chip IC (U1), thus reducing the complexity of the IC (U1) which in turn increases the reliability of both overvoltage detecting and current leakage detection since they are not interdependent. It also reduces the cost of IC since any standard Ground fault detection IC can be used instead of a special and costlier overvoltage and leakage current detection IC.
[0066] Moreover, in interpreting the specification, all terms should be interpreted in the broadest possible manner consistent with the context. In particular, the terms “comprises” and “comprising” should be interpreted as referring to elements, components, or steps in a non-exclusive manner, indicating that the referenced elements, components, or steps may be present, or utilized, or combined with other elements, components, or steps that are not expressly referenced. Where the specification claims refer to at least one of something selected from the group consisting of A, B, C …and N, the text should be interpreted as requiring only one element from the group, not A plus N, or B plus N, etc.
[0067] While the foregoing describes various embodiments of the invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof. The scope of the invention is determined by the claims that follow. The invention is not limited to the described embodiments, versions or examples, which are included to enable a person having ordinary skill in the art to make and use the invention when combined with information and knowledge available to the person having ordinary skill in the art.

ADVANTAGES OF THE PRESENT DISCLOSURE
[0068] The present disclosure provides a circuit breaker for protecting an electrical device from leakage current and overvoltage.
[0069] The present disclosure provides provide an improved circuit breaker offering human protection, equipment protection and enhanced fire protection.
[0070] The present disclosure provides a protection circuit for a circuit breaker that eliminates need of customised integrated chip (IC), thereby providing economical design of the integrated circuit.
[0071] The present disclosure provides a protection circuit for a circuit breaker sharing a common actuator, thereby reducing the size of the circuit.
, Claims:1. A circuit breaker (100) for protecting an electrical device from leakage current and overvoltage, the circuit breaker (100) comprising:
a protection circuit (102) for detecting leakage current and overvoltage through the electrical device and/or the circuit breaker, the protection circuit (102) comprising a leakage current detection circuit (104) and an overvoltage detection circuit (106), wherein the protection circuit (102) is configured to trip the circuit breaker when:
the leakage current detection circuit (104) detects a rise in real-time current flowing through the circuit breaker being greater than a pre-defined threshold value, or
the overvoltage detection circuit (106) detects a real-time voltage across the circuit breaker being greater than a pre-defined breakdown voltage value.

2. The circuit breaker (100) as claimed in claim 1, wherein the leakage current detection circuit (104) comprises an electromagnetic coil (301), a power resistor (R4), a controller (U1), a first set of terminals (T1, T2), a current transformer (302) electrically coupled with the first set of terminals (T1, T2), a network of resistors (R2, R3, RF1) and a network of capacitors (C10, C11, C12).

3. The circuit breaker (100) as claimed in claim 2, wherein when the current transformer (302) detects a leakage current, a voltage is produced across a secondary winding of the current transformer (302) that is inputted to the controller (U1) to measure the produced voltage.

4. The circuit breaker (100) as claimed in claim 3, wherein the controller (U1) compares the measured voltage with the pre-defined threshold value, and in case the measured voltage is higher than the pre-defined threshold value, the controller (U1) produces a high current at at least one pin (P4) of the controller connected to a switching unit (U2) and actuates the switching unit (U2).

5. The circuit breaker (100) as claimed in claim 4, wherein the switching unit (U2) is connected in series with the electromagnetic coil (301), the actuated switching unit (U2) increases the current through the electromagnetic coil (301) and provides a fault or trip signal associated with leakage current to the circuit breaker (100).

6. The circuit breaker (100) as claimed in claim 1, wherein the overvoltage detection circuit (106) comprises a voltage bridge (501), a semi-conductor diode (DZ1) connected in series with the voltage bridge (501) and to a gate terminal of the switching unit (U2).

7. The circuit breaker (100) as claimed in claim 6, wherein the overvoltage detection circuit (106) is connected across a phase (P) terminal and a neutral (N) terminal for power supply.

8. The circuit breaker (100) as claimed in claim 7, wherein when a voltage across the Phase (P) and Neutral (N) terminals are in an overvoltage range, the voltage bridge (501) is calibrated in a manner that the voltage across the semi-conductor diode (DZ1) is greater than the pre-defined breakdown voltage value, that enables the current to flow through the semi-conductor diode (DZ1) and actuates the switching unit (U2) that is electrically coupled to the semi-conductor diode (DZ1).

9. The circuit breaker (100) as claimed in claim 8, wherein the actuated switching unit (U2) increases the current through the electromagnetic coil (301) and provides a fault or trip signal associated with overvoltage to the circuit breaker (100).

10. The circuit breaker (100) as claimed in claim 1, wherein a test circuit (108) is electrically coupled to the leakage current detection circuit (104), the test circuit (108) comprises a second set of terminals (T3, T4) looped through a primary of the current transformer (302), one or more second resistors (R7, R8, R9) and a switch (SW1), wherein the one or more resistors (R7, R8, R9) are arranged such that when the switch is turned ON, a calibrated leakage current flows through the primary of the current transformer (302) and generates an artificial leakage fault and the calibrated leakage current is detected by the leakage current detection circuit (104) that activates the electromagnetic coil (301) to provide a fault/ trip command.