A circuit breaker and a method of impedance detection of a contact mechanism thereof

Abstract

A kind of circuit breaker and contact mechanism resistance calculation method, including measuring circuit and energizing loop, each phase energizing loop includes a set of contact mechanism, the measuring circuit includes controller, current sensor and voltage measurement circuit, the current sensor, voltage measurement circuit is connected with controller respectively for delivering current signal and voltage signal to controller, the impedance of contact mechanism is calculated according to the current and voltage of contact mechanism by controller;The current sensor is connected in series with the contact mechanism, and the voltage measurement circuit is connected in parallel across the contact mechanism, and the voltage measurement circuit includes a voltage sensor and a switch device for controlling the on or off of the voltage measurement circuit.The present application makes the voltage measurement circuit on or off by controlling the switch device, and then the measuring circuit cannot form a current loop when the contact mechanism is tripped, to avoid the leakage hazard of circuit breaker.

Description

Technical Field

[0001] This invention relates to low-voltage electrical appliances, and more specifically to an impedance detection method for a circuit breaker and its contact mechanism. Background Technology

[0002] A circuit breaker, also known as an automatic air switch or automatic air circuit breaker, is an electrical appliance that functions as both a manual switch and an automatic protector against undervoltage, overload, and short circuit. It can be used to distribute electrical energy, infrequently start asynchronous motors, and protect power lines and motors. When serious overloads, short circuits, or undervoltage faults occur, it automatically disconnects the circuit, functioning similarly to a combination of a fuse switch and over / under-temperature relays.

[0003] The contact mechanism is a crucial component of a circuit breaker, controlling the energization or de-energization of a line through closing or opening. However, each closing and opening action causes attenuation of the contact mechanism, increasing the circuit breaker's impedance and consequently increasing power consumption and reducing transmission efficiency. As power consumption continues to rise, it eventually leads to circuit breaker failure. Currently, existing circuit breakers cannot measure the on-resistance of the contact mechanism in real time. The main reason is that the measurement circuit and the circuit breaker's wiring cannot be isolated. A small current generated during operation can flow through the load, potentially causing leakage and posing a safety hazard. Therefore, because the on-resistance of the contact mechanism cannot be measured in real time, the operating status of the circuit breaker and its lifespan cannot be accurately detected. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a circuit breaker with a simple structure and an impedance detection method for its contact mechanism that can accurately and reliably measure the impedance of the contact mechanism.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A circuit breaker includes a measuring circuit and at least one phase energized circuit. Each phase energized circuit includes a set of contact mechanisms for controlling the opening and closing of the energized circuit. The measuring circuit includes a controller, a current sensor, and a voltage measuring circuit. The current sensor and the voltage measuring circuit are respectively connected to the controller to transmit current signals and voltage signals to the controller. The controller calculates the impedance of the contact mechanism based on the current and voltage flowing through the contact mechanism.

[0007] The current sensor is connected in series with the contact mechanism, and the voltage measurement circuit is connected in parallel across the two ends of the contact mechanism. The voltage measurement circuit includes a voltage sensor and a switching device for controlling the voltage measurement circuit to be turned on or off. When the switching device is closed, the voltage sensor acquires the voltage across the two ends of the contact mechanism and transmits a voltage signal to the controller. When the switching device is open, no current flows through the voltage measurement circuit.

[0008] Furthermore, the switching device includes a switch connected in series with a voltage sensor and a drive structure for driving the switch to close or open.

[0009] Furthermore, the switch is a semiconductor power switch, and the driving structure includes a driving unit connected to the controller, which closes or opens the switch under the control of the controller.

[0010] Furthermore, the switch is a mechanical switch, and the driving structure includes a driving unit and a motor. The driving unit is connected to the controller and rotates the motor under the control of the controller. The rotation of the motor operates the closing or opening of the switch.

[0011] Furthermore, the drive unit, under the control of the controller, causes the motor to rotate, and the rotation of the motor operates the opening and closing of the contact mechanism and the opening or closing of the switch; or the rotation of the motor operates the opening and closing of the contact mechanism, and the opening and closing of the contact mechanism causes the switch to open or close.

[0012] Furthermore, the switch is a mechanical switch, and the driving structure is the operating mechanism of a circuit breaker. When the operating mechanism drives the contact mechanism to perform opening and closing actions, it drives the switch to open or close.

[0013] Furthermore, the switching device can disconnect the voltage measurement circuit before the contact mechanism opens; or, the switching device can operate synchronously with the contact mechanism to control the switching on and off of the voltage measurement circuit; or, the switching device can disconnect the voltage measurement circuit after the contact mechanism opens.

[0014] Furthermore, the controller includes two differential ADC modules. One differential ADC module acquires the current value through a current sensor, and the other differential ADC module acquires the voltage value of the contact mechanism through a voltage measurement circuit. The voltage measurement circuit does not have a voltage sensor. One end of the switching device is connected to one terminal of the contact mechanism, and the other end of the switching device and the other terminal of the contact mechanism are connected to the same differential ADC module of the controller.

[0015] Furthermore, the measurement circuit also includes a controllable current source driven by a controller. The controllable current source is connected in each phase energized circuit and can increase the current in the energized circuit under the drive of the controller.

[0016] Furthermore, the controllable current source includes an isolation drive controller and a controllable circuit controlled by the isolation drive controller. The two ends of the controllable circuit are respectively connected to the live wire and the neutral wire of the power-on circuit. The controllable circuit includes a first conducting element, a resistor and a second conducting element connected in sequence. Under the drive of the isolation drive controller, the first conducting element and the second conducting element are turned on. The isolation drive controller adjusts the current in the controllable circuit according to the voltage across the resistor.

[0017] Furthermore, the measurement circuit also includes one or more power supplies for providing operating power to the measurement circuit; the current sensor is a Hall sensor or a transformer, the voltage sensor is a resistor, and the controller is a microcontroller.

[0018] An impedance detection method for a contact mechanism in a circuit breaker includes the circuit breaker as described above. When the contact mechanism is closed, the controller of the circuit breaker obtains the current I flowing through the contact mechanism through a current sensor, the controller obtains the voltage V of the contact mechanism through a voltage measurement circuit, and the controller calculates and stores the impedance value of the contact mechanism based on the impedance Z = V / I.

[0019] Preferably, the controller obtains the impedance change value of the contact mechanism by comparing the impedance value at the nth closing and the (n-1th closing) of the contact mechanism, and thereby judges the working condition of the circuit breaker and predicts the life of the contact mechanism; where n is an integer greater than or equal to 1.

[0020] The present invention discloses a circuit breaker that can detect the impedance of the contact mechanism in each phase energized circuit through a measuring circuit. The voltage measuring circuit has a switching device, which controls the voltage measuring circuit by closing or opening the switching device. When it is not necessary to measure the voltage of the contact mechanism, the voltage measuring circuit is disconnected, so that the measuring circuit does not form a current loop when the contact mechanism is open, thus avoiding the generation of current flowing through the load and the potential leakage current of the circuit breaker.

[0021] In addition, the switching device includes a switch and a drive structure that works with the switch. The switch is connected in series in the voltage measurement circuit and is driven by the drive structure. Since there are many possible forms of the switch and the drive structure, it has strong applicability.

[0022] Furthermore, the drive structures used to drive the switch to close or open are diverse, and depending on the type of switch, they can be drive circuits, motors, and circuit breaker operating mechanisms, giving voltage measurement circuits a wide range of options and providing strong advantages in terms of applicability, cost, and assembly.

[0023] In addition, the measuring circuit is equipped with a controllable current source, which outputs a controllable current under the drive of the controller to increase the current flowing through the contact mechanism and improve the measurement accuracy; in addition, the measuring circuit is also equipped with a power supply to provide working power.

[0024] The present invention provides an impedance detection method for the contact mechanism in a circuit breaker. Based on the circuit breaker described above, the controller calculates the impedance value of the contact mechanism by acquiring the current and voltage of the contact mechanism. The method is reasonable, simple, and highly accurate.

[0025] In addition, by comparing the contact mechanism impedance value obtained from the previous measurement, the working status of the contact mechanism can be determined and the lifespan of the contact mechanism can be predicted. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the first embodiment of a circuit breaker according to the present invention (the second voltage probe is movable);

[0027] Figure 2 This is a schematic diagram of a first embodiment of a circuit breaker according to the present invention (the first voltage probe is movable);

[0028] Figure 3 This is a schematic diagram of the first embodiment of a circuit breaker according to the present invention (the second probe is a metal rod);

[0029] Figure 4 This is a schematic diagram of the first embodiment of a circuit breaker according to the present invention (three-phase four-wire circuit breaker);

[0030] Figure 5 This is a schematic diagram of a second embodiment of a circuit breaker according to the present invention (only driving the switch);

[0031] Figure 6 This is a circuit diagram of a second embodiment of a circuit breaker according to the present invention (driving switch only);

[0032] Figure 7 This is a schematic diagram of a second embodiment of a circuit breaker according to the present invention (driving switch and contact mechanism);

[0033] Figure 8 This is a circuit diagram (driving switch and contact mechanism) of a second embodiment of a circuit breaker according to the present invention;

[0034] Figure 9 This is a schematic diagram of a second embodiment of a circuit breaker according to the present invention (operating mechanism driving switch);

[0035] Figure 10 This is a circuit diagram (operating mechanism driving switch) of a second embodiment of a circuit breaker according to the present invention;

[0036] Figure 11This is a waveform diagram (pulse type) of the current generated by the controllable current source and the current generated by the energized circuit in a circuit breaker of the present invention.

[0037] Figure 12 This is a waveform diagram (continuous) of the current generated by the controllable current source and the current generated by the energized circuit in a circuit breaker according to the present invention. Detailed Implementation

[0038] The following is in conjunction with the appendix Figures 1 to 12 The given embodiments further illustrate specific implementations of the impedance detection method for a circuit breaker and its contact mechanism according to the present invention. The impedance detection method for a circuit breaker and its contact mechanism according to the present invention is not limited to the descriptions in the following embodiments.

[0039] A circuit breaker includes a measuring circuit and at least one phase energized circuit. Each phase energized circuit includes a set of contact mechanisms for controlling the opening and closing of the energized circuit. The measuring circuit is connected to each phase energized circuit and includes a controller, a current sensor, and a voltage measuring circuit that transmit signals to the controller. The current sensor is connected in series with the contact mechanism and measures the current flowing through the contact mechanism when it is closed. The current sensor transmits the obtained current signal to the controller. The voltage measuring circuit is connected in parallel across the two ends of the contact mechanism. When the contact mechanism is closed, the voltage measuring circuit is turned on to measure the voltage across the two ends of the contact mechanism and transmits the obtained voltage signal to the controller. When the contact mechanism is opened, the voltage measuring circuit is turned off, so that no current flows through the voltage measuring circuit or the entire measuring circuit. The controller calculates the impedance of the contact mechanism based on the obtained current and voltage.

[0040] The present invention discloses a circuit breaker that can detect the impedance of the contact mechanism in each phase energized circuit through a measuring circuit. The voltage measuring circuit used to measure the voltage of the contact mechanism can be controllably disconnected or turned on, so that no current flows through the voltage measuring circuit and the measuring circuit when the contact mechanism is opened, thereby avoiding the generation of current flowing through the load in the measuring circuit and the potential leakage current of the circuit breaker.

[0041] In this application, the voltage measurement circuit includes a voltage sensor and a switching device for controlling the on / off state of the voltage measurement circuit. When the switching device is closed, the voltage measurement circuit is connected, the voltage sensor acquires the voltage across the contact mechanism and transmits a voltage signal to the controller. When the switching device is open, no current flows through the voltage measurement circuit. Preferably, the operation of the switching device is driven by the controller. The switching device can be a mechanism with a travel function, or it can be a switch combination connected in series in the voltage measurement circuit. The switch combination includes a switch and a drive structure for driving the switch. Specifically, it can be a combination of a semiconductor power switch and a drive unit, or a combination of a mechanical switch that can be driven and the operating mechanism of a circuit breaker, or a mechanical switch and a separately provided drive structure.

[0042] Furthermore, the switching device can disconnect the voltage measurement circuit synchronously with the opening action of the contact mechanism, or before the opening action of the contact mechanism, or immediately disconnect within a short time after the contact mechanism opens.

[0043] Preferably, the measurement circuit also includes a controllable current source driven by the controller. When the current in the energized circuit obtained by the controller through the current sensor is small, the small current is not conducive to accurately measuring the impedance of the contact mechanism. The controller drives the controllable current source to output current to increase the current in the energized circuit. This can reduce the sensitivity requirements of the current sensor and make the measurement results more accurate.

[0044] Furthermore, the measurement circuit also includes a power supply, which provides operating power to the measurement circuit. The number of power supplies can be set to one or more according to actual needs. The power supply can be directly drawn from the power-on circuit and converted into a voltage suitable for powering the measurement circuit, or it can be a battery.

[0045] In this application, the controller is an integrated circuit with certain logic operation and storage capabilities. The controller is preferably a microcontroller. The current sensor is a Hall sensor, transformer or resistor, and the voltage sensor is a resistor.

[0046] Combination Figure 1-4 An embodiment of a first type of circuit breaker is provided, in which the switching device is a mechanism with a travel function driven by a controller, and under the action of the controller, the switching device generates a displacement to close or open the voltage measuring circuit.

[0047] Combination Figure 1-3 A single-phase circuit breaker structure is provided. The circuit breaker's energizing circuit includes a live wire and a neutral wire. The contact mechanism of the energizing circuit is connected to the live wire; alternatively, a contact mechanism can also be installed on the neutral wire. In this embodiment, the contact mechanism is connected to the live wire. The two ends of the measuring circuit are connected to the first and second terminals of the contact mechanism, respectively. In this embodiment, the first terminal of the contact mechanism is the circuit breaker's input terminal, connected to the side of the live wire marked as terminal A in the figure. The second terminal of the contact mechanism is the circuit breaker's output terminal, i.e., the load side of the circuit breaker, connected to the side of the live wire marked as terminal B in the figure. A current sensor of the measuring circuit is connected in series with the first terminal of the contact mechanism to obtain the current flowing through the contact mechanism. A voltage measuring circuit is connected in parallel with the contact mechanism to obtain the voltage of the contact mechanism. The current sensor and voltage measuring circuit are connected to a controller to transmit current and voltage signals to the controller. The controller calculates the impedance of the contact mechanism based on the current and voltage flowing through it.

[0048] In this embodiment, the controller is a microprocessor, and includes at least one differential ADC module. Preferably, the controller has two differential ADC modules. One differential ADC module can directly read the current value output by the current sensor, and the other differential ADC module can directly read the voltage value across the contact mechanism through a voltage measurement circuit, and can convert the analog signals of current and voltage into digital signals for calculation. Of course, a separate analog-to-digital converter circuit can also be used, separate from the controller.

[0049] The voltage measurement circuit includes a voltage sensor and a switching device driven by a controller. The switching device controls the on / off state of the voltage measurement circuit under the drive of the controller. The switching device can disconnect the voltage measurement circuit before the contact mechanism opens, or it can operate synchronously with the contact mechanism to disconnect the voltage measurement circuit. Of course, it can also disconnect within a short time after the contact mechanism opens. Preferably, the voltage measurement circuit is disconnected within 60 seconds after the contact mechanism opens to avoid the risk of leakage current from the circuit breaker due to prolonged connection.

[0050] In this embodiment, the voltage measurement circuit includes a voltage sensor, two voltage probes, and a transmission mechanism. The voltage sensor is connected to the controller for signal transmission. The connection terminals of the two voltage probes are respectively connected to the two ends of the voltage sensor. The sensing terminals of the two voltage probes are respectively used to contact and connect with the first and second terminals of the contact mechanism (or connect with the live wires near the first and second terminals). The transmission mechanism is connected to at least one voltage probe to form a mechanism with a travel function. The transmission mechanism operates under the drive of the controller, causing the voltage probe connected to the transmission mechanism to be displaced and its sensing terminal to separate or contact the terminal of the contact mechanism, thereby controlling the on / off state of the voltage measurement circuit. It should be noted that the voltage probe can be made of any conductive material, without limitation on its material and shape, and can also be a filter circuit with signal amplification and attenuation. When the voltage probe is connected to the terminal of the contact mechanism in a non-physical contact manner, the voltage measurement circuit can be considered disconnected when the transmission mechanism drives the voltage probe to move its sensing terminal out of the sensing range of the terminal of the contact mechanism.

[0051] Combination Figure 1 , 3A specific connection method for a voltage measurement circuit is provided, comprising two voltage probes, a first voltage probe and a second voltage probe. The voltage sensor transmits signals to a controller, and its two ends are connected to the connection terminals of the first and second voltage probes, respectively. The sensing end of the first voltage probe remains connected to the first terminal of the contact mechanism. The second voltage probe is connected to a transmission mechanism and, driven by the transmission mechanism, undergoes displacement, causing the sensing end of the second voltage probe to contact or separate from the second terminal of the contact mechanism. Alternatively, the first voltage probe can also be connected to the transmission mechanism, causing its sensing end to contact or separate from the first terminal of the contact mechanism (see [link to relevant documentation]). Figure 2 Alternatively, the first voltage probe and the second voltage probe are both driven by the transmission mechanism (not shown), so that their sensing ends contact or separate from the first and second terminals of the contact mechanism, respectively. In this structure, the sensing ends of the two voltage probes can contact the terminals of the contact mechanism simultaneously, or they can contact the terminals of the contact mechanism sequentially.

[0052] like Figure 3 As shown, the sensing end of the first voltage probe is directly connected to the first terminal of the contact mechanism (or the live wire near the first terminal). The connection end of the first voltage probe is connected to the differential ADC module of the controller. The second voltage probe is a metal rod. Preferably, the metal rod can also act as a resistor and a voltage sensor. One end of the metal rod is connected to the first probe via a wire to the same differential ADC module of the controller. Alternatively, another voltage sensor can be provided. The outer wall of the metal rod has an external thread. The transmission mechanism includes a motor driven by the controller and a gear set meshing with the motor. The gear set includes at least one gear meshing with the metal rod. Under the drive of the controller, the motor rotates in the forward or reverse direction. The gear set drives the other end of the metal rod, which acts as the sensing end, to move closer to or away from the second terminal. When the metal rod contacts the second terminal, the voltage measurement circuit is turned on, and the voltage sensor can obtain the voltage across the two ends of the contact mechanism. When the metal rod is separated from the second terminal, the voltage measurement circuit is turned off, the voltage sensor does not work, and no current flows through the voltage measurement circuit. Preferably, the motor is started when the controller detects that the contact mechanism has opened, thus separating the metal rod from the first terminal. Furthermore, the structure of the sensing end of the second voltage probe is not limited to a metal rod structure; other forms of movable voltage probes are also applicable. The transmission mechanism with a stroke structure is not limited to a combination of a motor and gear set; it can be an electromagnetic structure with a stroke mechanism, such as an electromagnet.

[0053] In this embodiment, a controllable current source is preferably also provided. This controllable current source generates a controllable additional current under the drive of the controller. This additional current can be a pulsed current or a continuous current. The controllable current source is activated only when the controller detects a low current through the current sensor, and it is located at the second terminal of the contact mechanism. Thus, when the current flowing through the energized circuit is small, the controller drives the controllable current source to generate an additional current, thereby reducing the sensitivity requirement of the current sensor and improving measurement accuracy. The additional current generated by the controllable current source can be pulsed (see...). Figure 11 It can also be continuous (see...). Figure 12 ).

[0054] Specifically, the controllable current source includes an isolation drive controller and a controllable circuit controlled by the isolation drive controller. The two ends of the controllable circuit are respectively connected to the second terminal of the contact mechanism and the neutral line of the power-on circuit. The controllable circuit includes a first conducting element, a resistor, and a second conducting element connected in sequence. Under the drive of the isolation drive controller, the first conducting element and the second conducting element conduct, causing current to flow in the controllable circuit. The isolation drive controller adjusts the current in the controllable circuit according to the voltage across the resistor. The first conducting element and the second conducting element are preferably field-effect transistors. The gate (G) of the first conducting element and the second conducting element are connected to the isolation drive controller, the source (S) of the first conducting element and the second conducting element are respectively connected to the two ends of the resistor, and the drain (D) of the first conducting element and the second conducting element are respectively connected to the live wire and the neutral line of the power-on circuit.

[0055] Furthermore, the measurement circuit is also equipped with a power supply, which can be one or more. The power supply is used to provide working power for the controller, current sensor, voltage sensor, transmission mechanism and controllable current source. The power supply can be directly drawn from the power circuit or it can be a battery.

[0056] Combination Figure 4This embodiment is applied to a three-phase four-wire circuit breaker. The circuit breaker includes three-phase energized circuits, namely phase A, phase B, and phase C. A set of contact mechanisms is provided on the live wire of each phase energized circuit. A current transformer is connected to the first terminal of each phase contact mechanism. All current transformers are connected to the same controller to provide the controller with the current signal flowing through each phase contact mechanism. A voltage measurement circuit is connected in parallel to the two terminals of each phase contact mechanism. The three voltage measurement circuits are connected to the same controller to provide the controller with the voltage signal of each phase contact mechanism. The opening and closing of each voltage measurement circuit is also driven by the controller. Each voltage measurement circuit includes a voltage sensor, two voltage probes, and a transmission mechanism. The two ends of the voltage sensor are respectively connected to the connection terminals of one voltage probe. The sensing end of the voltage probe is used to connect to the terminals at both ends of the contact mechanism. At least one voltage probe is connected to the transmission mechanism, and under the drive of the transmission mechanism, the sensing end of the voltage probe contacts or separates from the terminal of the contact mechanism. Figure 4 In this circuit, the sensing end of one voltage probe is connected to one terminal of the contact mechanism, preferably the first terminal of the contact mechanism, which is the incoming terminal of the circuit breaker. The sensing end of the other voltage probe can contact or separate from the second terminal of the contact mechanism under the drive of the transmission mechanism, thereby realizing the control of the on / off state of the voltage measurement circuit.

[0057] In addition, a controllable current source is connected in each phase energized circuit. Its specific structure is the same as the connection and working principle of the single-phase circuit breaker in this embodiment. At the same time, a power supply is also provided in the three-phase four-wire circuit breaker. The power supply is used to provide working power for all current sensors, voltage sensors, controllers and controllable current sources.

[0058] Combination Figure 5-10 A second embodiment of a circuit breaker is provided. In this embodiment, the switching device is a switch combination for controlling a voltage measurement circuit. The switching device includes a switch and a drive structure for driving the switch. The drive structure can be a drive unit, a combination of a drive unit and a motor, a combination of a drive unit, a motor, and a contact mechanism, or the operating mechanism of a circuit breaker. Because switch combinations are diverse, the switching device has significant advantages in terms of applicability, cost, and assembly.

[0059] like Figure 5-10As shown, a single-phase circuit breaker is used as an example, but the structure is equally applicable to three-phase four-wire circuit breakers or three-phase three-wire circuit breakers, etc. Similar to the first embodiment, the circuit breaker's energizing circuit includes a live wire and a neutral wire. The contact mechanism of the energizing circuit is connected to the live wire. Of course, a set of contact mechanisms can also be installed on the neutral wire. In this embodiment, the contact mechanism is connected to the live wire. The two ends of the measuring circuit are respectively connected to the two terminals of the contact mechanism, namely the first terminal and the second terminal of the contact mechanism. In this embodiment, the first terminal of the contact mechanism is the input terminal of the circuit breaker. In the figure, the first terminal is connected to the side of the live wire marked as terminal A. The second terminal of the contact mechanism is the output terminal of the circuit breaker, that is, the load side of the circuit breaker. In the figure, the second terminal is connected to the side of the live wire marked as terminal B. The current sensor of the measuring circuit is connected in series with the first terminal of the contact mechanism to obtain the current flowing through the contact mechanism. The voltage measuring circuit is connected in parallel with the contact mechanism to obtain the voltage of the contact mechanism. The current sensor and the voltage measuring circuit are respectively connected to the controller to transmit current signals and voltage signals to the controller. The controller calculates the impedance of the contact mechanism based on the current and voltage flowing through the contact mechanism.

[0060] The voltage measurement circuit includes a voltage sensor and a switching device for controlling the on / off state of the voltage measurement circuit. Unlike the first embodiment, the switching device may or may not be controlled by a controller. Furthermore, the switching device can disconnect the voltage measurement circuit before the contact mechanism opens, meaning the switching device completes the disconnection action before the contact mechanism fully opens. Alternatively, the switching device can immediately disconnect after acquiring the voltage value at the moment of connection, or it can operate synchronously with the contact mechanism to disconnect the voltage measurement circuit. Of course, it can also disconnect within a short time after the contact mechanism opens, preferably within 60 seconds of the contact mechanism opening, to avoid the risk of leakage current in the circuit breaker due to prolonged connection. In addition, in some intelligent circuit breakers, both the contact mechanism and the switching device are controlled by a controller. In this case, the switching device and the contact mechanism can be disconnected in stages through control.

[0061] like Figure 6 , 8 As shown in Figure 10, in this embodiment, the controller is a microprocessor (labeled MCU). The controller includes at least one differential ADC module, preferably two. One differential ADC module can directly read the current value output by the current sensor, and the other differential ADC module directly reads the voltage value across the contact mechanism through a voltage measurement circuit. The differential ADC modules can convert analog current and voltage signals into digital signals for calculation. Alternatively, the voltage measurement circuit may not include a voltage sensor. In this case, one end of the switch and one terminal of the contact mechanism are connected to the same differential ADC module, and the other end of the switch is connected to another terminal of the contact mechanism.

[0062] Preferably, the controller can also acquire the opening and closing status of the contact mechanism, and control the on / off state of the voltage measurement circuit in the measurement circuit according to the opening and closing status of the contact mechanism. The controller can acquire the opening and closing status of the contact mechanism through a current sensor, or it can acquire the opening and closing status of the contact mechanism through other detection devices.

[0063] The voltage measurement circuit includes a voltage sensor and a switching device, which includes a switch and a driving structure. The voltage sensor is connected to a controller for signal transmission. Unlike the first embodiment, one end of the voltage sensor is directly connected to the first terminal of the contact mechanism (or the live wire near the first terminal), and the other end of the voltage sensor is connected to one end of the switch. The other end of the switch is also directly connected to the second terminal of the contact mechanism (or the live wire near the second terminal). The switching on and off of the voltage measurement circuit is controlled by the closing or opening of the switch. There are various forms of driving structures that drive the switch to close or open.

[0064] Combination Figure 5 , 6 This embodiment provides a first driving structure, which is connected to a controller. Under the drive of the controller, the switch is closed or opened, thereby controlling the voltage measurement circuit. The driving structure includes a driving unit and / or a motor. When the switch is a semiconductor power switch, the driving unit may only be a driving circuit, which closes or opens the switch under the control of the controller. When the switch is a mechanical switch, the driving structure may only include a motor, which rotates under the drive of the controller, thereby closing or opening the switch. Of course, the driving structure may also be a combination of a driving unit and a motor, with the controller controlling the rotation of the motor through the driving unit, and the motor operating the closing or opening of the switch.

[0065] Combination Figure 7 , 8 A second driving structure is provided in this embodiment. In addition to closing or opening the switch, the driving structure can also drive the opening and closing of the contact mechanism. Specifically, the driving structure includes a driving unit, a motor and a contact mechanism.

[0066] This application provides three coordination methods, but is not limited to the following three: First, the controller drives the motor to rotate through the drive unit, and the rotation of the motor causes the contact mechanism to perform opening and closing actions. At the same time as the motor drives the contact mechanism to perform opening and closing actions, the drive unit synchronously drives the switch, which serves as a switching device, to open or close. In this case, the switch is preferably a semiconductor power switch. Second, the controller drives the motor to rotate through the drive unit, and the rotation of the motor drives the contact mechanism to perform opening and closing actions as well as the opening or closing of the switch. In this case, the switch is preferably a mechanical switch. Third, the controller drives the motor to rotate through the drive unit, and the contact mechanism performs opening and closing actions under the action of the motor. When the contact mechanism performs opening and closing actions, the contact mechanism drives the switch to open or close.

[0067] It should be noted that the driving unit in the above driving structure is preferably a driving circuit controlled by a controller.

[0068] Combination Figure 9 , 10 A third driving structure is provided in this embodiment. The driving structure is the operating mechanism of the circuit breaker. When the operating mechanism of the circuit breaker drives the contact mechanism to perform opening and closing actions, it can also drive the switch to perform opening or closing actions. Preferably, the switch is a mechanical switch. In this way, when the contact mechanism is closed, the voltage measurement circuit is turned on, and when the contact mechanism is opened, the voltage measurement circuit is turned off. In addition, in this structure, the operating mechanism of the circuit breaker can be independent of the controller of the measurement circuit.

[0069] In this embodiment, a controllable current source, identical to that in the first embodiment, is also provided. This controllable current source is connected to the second terminal of the contact mechanism, which is the load side of the circuit breaker. When the current obtained by the controller through the current sensor is small, the controller drives the controllable current source to output a controllable current into the energized circuit, thereby increasing the current in the energized circuit. This reduces the sensitivity requirement of the current sensor and improves measurement accuracy. The controllable current source can be a controllable power switch or a variable resistor, and the current magnitude is changed by adjusting the value of the variable resistor.

[0070] like Figure 6 , 8As shown in Figure 10, similar to the first embodiment, the controllable current source includes an isolation drive controller and a controllable circuit controlled by the isolation drive controller. The two ends of the controllable circuit are respectively connected to the second terminal of the contact mechanism and the neutral line of the power-on circuit. The controllable circuit includes a first conducting element, a resistor, and a second conducting element connected in sequence. Under the drive of the isolation drive controller, the first conducting element and the second conducting element conduct, causing current to flow in the controllable circuit. The isolation drive controller adjusts the current in the controllable circuit according to the voltage across the resistor. The first conducting element and the second conducting element are preferably field-effect transistors. The gate (G) of the first conducting element and the second conducting element are connected to the isolation drive controller. The source (S) of the first conducting element and the second conducting element are respectively connected to the two ends of the resistor. The drain (D) of the first conducting element and the second conducting element are respectively connected to the live wire and the neutral line of the power-on circuit. Preferably, the first conducting element and the second conducting element are field-effect transistors.

[0071] In this application, the current sensor is a Hall sensor, a transformer, or a resistor, and the voltage sensor is a resistor.

[0072] An impedance detection method for the contact mechanism in a circuit breaker includes the circuit breaker described in the two embodiments above. When the contact mechanism is closed, the controller obtains the current I flowing through the contact mechanism through a current sensor, the controller obtains the voltage V of the contact mechanism through a voltage measurement circuit, and the controller calculates and stores the impedance value of the contact mechanism based on the impedance Z = V / I. The method is simple and accurate.

[0073] Furthermore, the controller obtains the impedance change of the contact mechanism by comparing the impedance value at the nth closing time with that at the (n-1th closing time), and thereby judges the working condition of the contact mechanism and predicts its lifespan; where n is an integer greater than or equal to 1.

[0074] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A circuit breaker, comprising a measuring circuit and at least one phase energized circuit, each phase energized circuit comprising a set of contact mechanisms for controlling the opening and closing of the energized circuit, the measuring circuit comprising a controller, a current sensor and a voltage measuring circuit, the current sensor and the voltage measuring circuit being respectively connected to the controller for transmitting current signals and voltage signals to the controller, the controller calculating the impedance of the contact mechanism based on the current and voltage flowing through the contact mechanism; The current sensor is connected in series with the contact mechanism, and the voltage measurement circuit is connected in parallel across the two ends of the contact mechanism, characterized in that: When the contact mechanism is closed, the voltage measurement circuit is turned on to measure the voltage across the contact mechanism and transmit the obtained voltage signal to the controller. When the contact mechanism is opened, the voltage measurement circuit is turned off. The voltage measurement circuit includes a voltage sensor and a switching device for controlling the voltage measurement circuit to be turned on or off. When the switching device is closed, the voltage sensor acquires the voltage across the contact mechanism and transmits the voltage signal to the controller. When the switching device is open, no current flows through the voltage measurement circuit. The measurement circuit also includes a controllable current source driven by a controller. The controllable current source is connected in each phase energized circuit. When the current flowing through the energized circuit is small, the controller drives the controllable current source to generate additional current to increase the current in the energized circuit. The controllable current source includes an isolation drive controller and a controllable circuit controlled by the isolation drive controller. The two ends of the controllable circuit are respectively connected to the live wire and the neutral wire of the energized circuit.

2. A circuit breaker according to claim 1, characterized in that: The switching device includes a switch connected in series with a voltage sensor and a drive structure that drives the switch to close or open.

3. A circuit breaker according to claim 2, characterized in that: The switch is a semiconductor power switch, and the driving structure includes a driving unit connected to the controller. The driving unit closes or opens the switch under the control of the controller.

4. A circuit breaker according to claim 2, characterized in that: The switch is a mechanical switch, and the driving structure includes a driving unit and a motor. The driving unit is connected to the controller and rotates the motor under the control of the controller. The rotation of the motor operates the closing or opening of the switch.

5. A circuit breaker according to claim 4, characterized in that: The drive unit, under the control of the controller, causes the motor to rotate. The rotation of the motor operates the opening and closing of the contact mechanism and the opening or closing of the switch; or the rotation of the motor operates the opening and closing of the contact mechanism, and the opening and closing of the contact mechanism causes the switch to open or close.

6. A circuit breaker according to claim 2, characterized in that: The switch is a mechanical switch, and the driving structure is the operating mechanism of the circuit breaker. When the operating mechanism drives the contact mechanism to perform opening and closing actions, it drives the switch to open or close.

7. A circuit breaker according to claim 1, characterized in that: The switching device can disconnect the voltage measurement circuit before the contact mechanism opens; or, the switching device can operate synchronously with the contact mechanism to control the switching on and off of the voltage measurement circuit; or, the switching device can disconnect the voltage measurement circuit after the contact mechanism opens.

8. A circuit breaker according to claim 1, characterized in that: The controller includes two differential ADC modules. One differential ADC module acquires the current value through a current sensor, and the other differential ADC module acquires the voltage value of the contact mechanism through a voltage measurement circuit. The voltage measurement circuit does not have a voltage sensor. One end of the switching device is connected to one terminal of the contact mechanism, and the other end of the switching device and the other terminal of the contact mechanism are connected to the same differential ADC module of the controller.

9. A circuit breaker according to claim 1, characterized in that: The controllable circuit includes a first conducting element, a resistor, and a second conducting element connected in sequence. Under the drive of the isolation drive controller, the first conducting element and the second conducting element are turned on, and the isolation drive controller adjusts the current in the controllable circuit according to the voltage across the resistor.

10. A circuit breaker according to claim 1, characterized in that: The measurement circuit also includes one or more power supplies for providing operating power to the measurement circuit; the current sensor is a Hall sensor or a transformer, the voltage sensor is a resistor, and the controller is a microcontroller.

11. An impedance detection method for the contact mechanism in a circuit breaker, characterized in that: The circuit breaker as described in any one of claims 1-10, when the contact mechanism is closed, the controller of the circuit breaker obtains the current I flowing through the contact mechanism through a current sensor, obtains the voltage V of the contact mechanism through a voltage measurement circuit, and calculates and stores the impedance value of the contact mechanism based on the impedance Z = V / I of the contact mechanism.

12. The impedance detection method for the contact mechanism in a circuit breaker according to claim 11, characterized in that: The controller obtains the impedance change value of the contact mechanism by comparing the impedance value at the nth closing and the (n-1)th closing of the contact mechanism, and thereby judges the working condition of the circuit breaker and predicts the life of the contact mechanism; where n is an integer greater than or equal to 1.

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