Electric leakage detection unit and circuit breaker
By using at least two current transformers in low-voltage electrical appliances and using differential comparison circuits to detect leakage, the assembly difficulty problem of multi-pole products penetrate multiple conductors into the magnetic ring is solved, achieving lower assembly difficulty and more flexible conductor distribution.
Patent Information
- Application Number
- CN202510273327.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-07
- Publication Date
- 2025-05-16
AI Technical Summary
In existing low-voltage electrical appliances, the way multi-pole products penetrate multiple conductors into the magnetic ring leads to high process requirements, difficult assembly, and difficult conductors pass through the magnetic core of the current transformer.
At least two current transformers are used, and each current transformer can pass through some conductors. The mutual inductance signals output by multiple current transformers are compared and integrated into the comparison signals for detecting leakage and driving the tripper operation.
This reduces the dimensional requirements of the current transformer and the difficulty of conductors passing through the core of the current transformer, simplifies the assembly process, and improves the flexibility of conductor distribution and the versatility of the current transformer.
Smart Images
Figure CN120016406A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of low-voltage electrical appliances, and in particular to a leakage detection unit and a circuit breaker. Background Art
[0002] A residual current operated circuit breaker is a safety protection device used in electrical systems. It can detect leakage in the circuit and quickly disconnect the circuit when current leakage or imbalance occurs to prevent electric shock or electrical fire. In related technologies, multi-pole products need to insert multiple wires into the magnetic ring to achieve leakage detection. The shape and length of the multiple wires are affected by the position of the magnetic ring, resulting in high process requirements, difficult assembly, and small electrical clearance. Summary of the invention
[0003] In view of this, the present application provides a leakage detection unit and a circuit breaker to improve the problem of difficulty in assembly in a method of detecting leakage by inserting a wire into a magnetic ring.
[0004] The technical solution adopted by this application to solve the above technical problems is:
[0005] In a first aspect, an embodiment of the present application provides a leakage detection unit, comprising:
[0006] a plurality of conductors of a low voltage circuit to be protected;
[0007] At least two current transformers, a portion of the plurality of conductors passes through the magnetic core of one current transformer to output a first mutual inductance signal, and another portion of the conductors passes through the magnetic core of another current transformer to output a second mutual inductance signal;
[0008] A differential comparison circuit, wherein the input end of the differential comparison circuit is electrically connected to the secondary windings of the two current transformers, respectively, and is used to compare the first mutual inductance signal with the second mutual inductance signal, and output a comparison signal;
[0009] A signal processing circuit, wherein the input end of the signal processing circuit is electrically connected to the output end of the differential comparison circuit, and the output end is electrically connected to the release.
[0010] In some embodiments of the present application, the number of the current transformers is two, the two current transformers are connected in parallel, and the number of conductors passing through the current transformers is equal.
[0011] In some embodiments of the present application, the plurality of conductors include L1, L2, L3 and N lines, two of which pass through one of the current transformers, and the other two pass through another current transformer.
[0012] In some embodiments of the present application, the first mutual inductance signal is the current vector sum of the conductors passing through one of the current transformers; the second mutual inductance signal is the current vector sum of the conductors passing through the other current transformer.
[0013] In some embodiments of the present application, the comparison signal is a current vector sum of the first mutual inductance signal and the second mutual inductance signal.
[0014] In some embodiments of the present application, when the current vector sum of the first mutual inductance signal and the second mutual inductance signal is equal to 0, a comparison signal indicating that the circuit is normal is output; when the current vector sum of the first mutual inductance signal and the second mutual inductance signal is not equal to 0, a comparison signal indicating that the circuit is leaking is output.
[0015] In some embodiments of the present application, the signal processing circuit includes:
[0016] A signal extraction module, used for extracting the comparison signal;
[0017] A filtering module, used for filtering the comparison signal;
[0018] A comparison module, used for comparing the comparison signal with a preset signal threshold;
[0019] The driving module is used to receive the comparison result of the comparison module and perform actions according to the comparison result.
[0020] In some embodiments of the present application, when the current vector sum of the first mutual inductance signal and the second mutual inductance signal is greater than the preset signal threshold, the driving module drives the release to operate; when the current vector sum of the first mutual inductance signal and the second mutual inductance signal is less than or equal to the preset signal threshold, the driving module maintains the current state.
[0021] In a second aspect, the present application provides a circuit breaker, comprising:
[0022] Power module;
[0023] A main circuit, electrically connected to the power module;
[0024] The leakage detection unit as described in the first aspect is electrically connected to both the main circuit and the power module;
[0025] The release is connected to the main circuit and the output end of the signal processing circuit.
[0026] In some embodiments of the present application, the circuit breaker further includes a button detection circuit, which is electrically connected to both the leakage detection unit and the main circuit and is used to simulate leakage current.
[0027] In summary, due to the adoption of the above technical solution, this application has at least the following beneficial effects:
[0028] The embodiment of the present application provides a leakage detection unit and a circuit breaker. By setting at least two current transformers and allowing each current transformer to pass through a part of the conductor, compared with using one current transformer to pass through all the conductors, the size requirements of the current transformer are lower, the difficulty of the conductor passing through the magnetic core of the current transformer is lower, the assembly difficulty is lower, and the distribution position of multiple conductors is more flexible. The purpose of reducing the length and volume of the conductor and the difference between multiple conductors can be achieved by flexibly distributing the conductor position. The uniform inner diameter of the current transformer also improves the versatility of the current transformer between single-phase and three-phase products. Then, by using a differential comparison circuit to compare the mutual inductance signals output by multiple current transformers and integrate the comparison signal, it can be known from the comparison signal whether there is leakage in the circuit in the current circuit breaker, and the signal processing circuit processes the comparison signal to obtain the result of driving or not driving the release action. BRIEF DESCRIPTION OF THE DRAWINGS
[0029] Figure 1 A schematic diagram of the structure of a leakage detection unit provided in an embodiment of the present application;
[0030] Figure 2 A structural block diagram of a circuit breaker provided in an embodiment of the present application.
[0031] Description of reference numerals:
[0032] 1. Circuit transformer; 2. Conductor, power module; 2. Main circuit; 3. Leakage detection unit; 31. Conductor; 32. Current transformer; 33. Differential comparison circuit; 34. Signal processing circuit; 341. Signal extraction module; 342. Filter module; 343. Comparison module; 344. Drive module; 4. Release; 5. Button detection circuit. DETAILED DESCRIPTION
[0033] The technical solutions in the embodiments of the present application will be described below in conjunction with the drawings in the embodiments of the present application.
[0034] In the description of this application, it should be understood that the words "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.
[0035] In this application, the word “exemplary” is used to mean “serving as an example, instance, or illustration.” Any embodiment described in this application as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments.
[0036] See also Figure 2 , an embodiment of the present application provides a circuit breaker, including a power module, a main circuit, a leakage detection unit and a release. The power module is electrically connected to the main circuit and the leakage detection unit to provide electrical energy. The main circuit is mainly used to connect external devices to cooperate with other structures of the circuit breaker to achieve the connection and disconnection between external devices. The leakage detection unit is also electrically connected to the main circuit so that the leakage detection unit can detect the current condition of the main circuit and promptly discover the leakage condition of the main circuit. The release is connected to the output end of the signal processing circuit in the main circuit and the leakage detection unit, and is mainly used to perform a tripping action according to the drive signal output by the output end of the signal processing circuit to disconnect the main circuit.
[0037] Furthermore, the circuit breaker also includes a button detection circuit, which is electrically connected to the leakage detection unit and the main circuit, and is used to simulate the leakage current. Exemplarily, when the circuit breaker is in the testing stage, in order to test whether the circuit breaker can accurately operate in the case of leakage and disconnect the main circuit, it is necessary to use the button detection circuit to provide a leakage current for the main circuit. When the leakage detection unit detects the simulated leakage current and the current value of the leakage current exceeds the preset safety threshold, it will drive the release to operate to disconnect the main circuit, ensure circuit safety, and avoid damage to the circuit breaker.
[0038] In some embodiments, see Figure 1 The leakage detection unit includes at least two current transformers 1, multiple conductors 2 of the low-voltage current to be protected, a differential comparison circuit and a signal processing circuit. Among them, the multiple conductors 2 of the low-voltage current to be protected are mainly used to connect the main circuit. A part of the multiple conductors 2 passes through the magnetic core of a current transformer 1 to output a first mutual inductance signal, and another part of the conductors 2 passes through the magnetic core of another current transformer 1 to output a second mutual inductance signal. It should be noted that the first mutual inductance signal refers to the current vector sum of the conductors 2 passing through one of the current transformers 1, and the second mutual inductance signal refers to the current vector sum of the conductors 2 passing through the other current transformer 1. The input end of the differential comparison circuit is electrically connected to the secondary windings of the two current transformers 1, respectively, for comparing the first mutual inductance signal and the second mutual inductance signal, and outputting a comparison signal. The input end of the signal processing circuit is electrically connected to the output end of the differential comparison circuit, and the output end is electrically connected to the release.
[0039] The technical solution provided by the present application is to set at least two current transformers 1, and each current transformer 1 can pass through part of the conductor 2. Compared with using one current transformer 1 to pass through all the conductors 2, the size requirements of the current transformer 1 are lower, the difficulty of the conductor 2 passing through the magnetic core of the current transformer 1 is lower, the assembly difficulty is lower, and the distribution position of multiple conductors 2 is more flexible. The purpose of reducing the length and volume of the conductor 2 and the difference between multiple conductors 2 can be achieved by flexibly distributing the position of the conductor 2. Then, the mutual inductance signals output by the multiple current transformers 1 are compared and integrated into a comparison signal by using a differential comparison circuit. From the comparison signal, it can be known whether there is leakage in the circuit of the current circuit breaker, and the signal processing circuit processes the comparison signal to obtain the result of driving or not driving the release action.
[0040] Exemplarily, the main circuit adopts a three-phase four-wire system, that is, the multiple conductors 2 are four conductors 2, and the conductors 2 can be conductive plates, wires, etc. In this embodiment, wires are used. The four conductors 2 are L1 line, L2 line, L3 line and N line. Two of the conductors 2 in the L1 line, L2 line, L3 line and N line pass through one of the current transformers 1, and the other two conductors 2 pass through another current transformer 1. The corresponding number of current transformers 1 is two, and each current transformer 1 is provided with two conductors 2. The two current transformers 1 are connected in parallel so that the currents detected by the two current transformers 1 are relatively independent, which facilitates the calculation of the current vector sum. Evenly distributing the four conductors 2 to the two current transformers 1 is conducive to simplifying the calculation and judgment of the current vector sum, and enabling the leakage detection unit to adapt to leakage current detection of two-pole or multi-pole circuits, such as two-pole or four-pole leakage current detection.
[0041] In one embodiment, L1 and L2 are passed through one current transformer 1, and L3 and N are passed through another current transformer 1. In another embodiment, L1 and L3 are passed through one current transformer 1, and L2 and N are passed through another current transformer 1. In another embodiment, L3 and L2 are passed through one current transformer 1, and L1 and N are passed through another current transformer 1.
[0042] In some embodiments, the two current transformers 1 may also be one of which has three conductors 2, and the other current transformer 1 has only one conductor 2. In one example, one of the current transformers 1 has L1, L2, and L3 lines, and the other current transformer 1 has N line. In another example, one of the current transformers 1 has L1, L2, and N lines, and the other current transformer 1 has L3 line. That is, as long as one of the current transformers 1 has three conductors 2, and the other current transformer 1 has one conductor 2, it will be sufficient. Because the technical solution requires the vector sum of the currents detected by the two current transformers 1, whether the two current transformers 1 are specifically penetrated by live wires or neutral wires is not limited here, as long as different conductors 2 are penetrated in the two current transformers 1.
[0043] In some embodiments, the number of current transformers 1 may be three or more, and the number of conductors 2 may be four or more, depending on actual conditions.
[0044] By passing all the conductors 2 through a current transformer 1, it is improved to group all the conductors 2, and then each group of conductors 2 is passed through a corresponding current transformer 1, and then the current vector summation of multiple groups of conductors 2 is performed, which can not only realize the detection of leakage current, but also reduce the inner diameter of the conductor 2 that needs to pass through each current transformer 1, increase the electrical gap, reduce the difficulty of installing the conductor 2 and the current transformer 1, make the distribution of the conductor 2 more flexible, and help shorten the length of the conductor 2.
[0045] In some embodiments, the differential comparison circuit is used to compare the first mutual inductance signal and the second mutual inductance signal, and output a comparison signal. The comparison signal is the current vector sum of the first mutual inductance signal and the second mutual inductance signal. By obtaining the comparison signal, it is determined whether there is leakage in the current main circuit according to whether the comparison signal is 0, that is, whether the current vector sum of the first mutual inductance signal and the second mutual inductance signal is 0.
[0046] Exemplarily, when the current vector sum of the first mutual inductance signal and the second mutual inductance signal is equal to 0, a comparison signal indicating that the circuit is normal is output; when the current vector sum of the first mutual inductance signal and the second mutual inductance signal is not equal to 0, a comparison signal indicating that the circuit is leaking is output.
[0047] In one example, the secondary winding of one current transformer 1 outputs a first mutual inductance signal, and the secondary winding of another current transformer 1 outputs a second mutual inductance signal, and the two signals are vector-superimposed through a differential comparison circuit. It can be understood that when the current vector sum of the first mutual inductance signal and the second mutual inductance signal is equal to 0, it means that there is no current leakage in the conductor 2 at this time. If the current vector sum of the first mutual inductance signal and the second mutual inductance signal is not equal to 0, it means that there is current leakage in at least one of the conductor 2 circuits, such as L1 line-to-ground leakage current, L2 line-to-ground leakage current, etc.
[0048] In some embodiments, the signal processing circuit includes a signal extraction module, a filtering module, a comparison module and a driving module. The signal extraction module is used to extract the comparison signal; the filtering module is used to filter the comparison signal; the comparison module is used to compare the comparison signal with a preset signal threshold; the driving module is used to receive the comparison result of the comparison module and perform an action according to the comparison result.
[0049] Exemplarily, the signal extraction module uses a high input impedance differential amplifier, whose positive and negative input terminals are respectively connected to the two output signals of the differential comparison circuit. The amplifier gain is set to 10 times, and a first-order RC high-pass filter network composed of resistors and capacitors is connected in series at the output terminal to eliminate the DC bias voltage and extract the AC leakage signal. The module amplifies the output signal of the transformer at the microvolt level to the volt level while maintaining the common mode rejection ratio (CMRR) ≥ 80dB. The filter module uses a second-order Butterworth low-pass filter, which can effectively filter out power frequency harmonics and high-frequency switching noise, thereby improving the signal-to-noise ratio of the signal. The comparison module adopts a window comparator structure and includes two high-speed comparator chips. The first comparator sets the positive threshold Vref_high, and the second comparator sets the negative threshold Vref_low. When the filtered signal exceeds the range of [Vref_low, Vref_high], the comparator outputs a high-level pulse signal. To adapt to different application scenarios, the threshold voltage is dynamically adjusted through a digital potentiometer with an adjustment accuracy of 0.1mA. The drive module consists of an optocoupler isolator and a MOSFET. The optocoupler input receives the pulse signal output by the comparison module, and the output drives the MOSFET to conduct, so that the trip coil is energized to generate magnetic force, which drives the mechanical trip mechanism to operate. To enhance the driving reliability, the MOSFET gate is connected in series with an RC buffer circuit, which can control the trip response time within 20ms.
[0050] Further, when the value of the current vector sum of the first mutual inductance signal and the second mutual inductance signal is greater than the preset signal threshold, the driving module drives the release to operate; when the current vector sum of the first mutual inductance signal and the second mutual inductance signal is less than or equal to the preset signal threshold, the driving module maintains the current state. By setting a signal processing circuit with a comparison module after the differential comparison circuit, the release is prevented from frequently triggering the tripping due to partial small current leakage, which is not conducive to the stable operation of the electrical equipment. Specifically, the technical solution provided by the present application is not to immediately drive the release to trip when the differential comparison circuit finds that there is a current leakage, but it is necessary to make a specific comparison and judgment on the current leakage, that is, to compare the detected current vector sum with the preset signal threshold. If it exceeds the threshold, it is determined that the current leakage may endanger the circuit safety. At this time, the release can be driven to trip by the driving module. If current leakage is detected, but it does not exceed the threshold, it means that the current leakage has no effect on current safety, and the release is not driven to trip, so as to avoid causing the circuit breaker to be overly sensitive and frequently tripped during use.
[0051] At the same time, the present application uses specific words to describe the embodiments of the present application. For example, "one embodiment", "an embodiment", and / or "some embodiments" refer to a certain feature, structure or characteristic related to at least one embodiment of the present application. Therefore, it should be emphasized and noted that "one embodiment" or "an embodiment" or "an alternative embodiment" mentioned twice or more in different positions in this specification does not necessarily refer to the same embodiment. In addition, some features, structures or characteristics in one or more embodiments of the present application can be appropriately combined.
[0052] Similarly, it should be noted that in order to simplify the description of the disclosure of this application and thus help understand one or more application embodiments, in the above description of the embodiments of the present application, multiple features are sometimes merged into one embodiment, figure or description thereof. However, this disclosure method does not mean that the features required by the object of the present application are more than the features mentioned in the claims. In fact, the features of the embodiments are less than all the features of the single embodiment disclosed above.
Claims
1. A leakage detection unit, characterized in that: include: a plurality of conductors of a low voltage circuit to be protected; At least two current transformers, a portion of the plurality of conductors passes through the magnetic core of one current transformer to output a first mutual inductance signal, and another portion of the conductors passes through the magnetic core of another current transformer to output a second mutual inductance signal; A differential comparison circuit, wherein the input end of the differential comparison circuit is electrically connected to the secondary windings of the two current transformers, respectively, and is used to compare the first mutual inductance signal with the second mutual inductance signal, and output a comparison signal; A signal processing circuit, wherein the input end of the signal processing circuit is electrically connected to the output end of the differential comparison circuit, and the output end is electrically connected to the release.
2. The leakage detection unit according to claim 1, characterized in that: The number of the current transformers is two, the two current transformers are connected in parallel, and the number of conductors passing through the current transformers is equal.
3. The leakage detection unit according to claim 2, characterized in that: The plurality of conductors include an L1 line, an L2 line, an L3 line, and an N line, two of which pass through one of the current transformers, and the other two pass through another current transformer.
4. The leakage detection unit according to claim 1, characterized in that: The first mutual inductance signal is the current vector sum of the conductors passing through one of the current transformers; the second mutual inductance signal is the current vector sum of the conductors passing through the other current transformer.
5. The leakage detection unit according to claim 4, characterized in that: The comparison signal is a current vector sum of the first mutual inductance signal and the second mutual inductance signal.
6. The leakage detection unit according to claim 5, characterized in that: When the current vector sum of the first mutual inductance signal and the second mutual inductance signal is equal to 0, a comparison signal of a normal circuit is output; when the current vector sum of the first mutual inductance signal and the second mutual inductance signal is not equal to 0, a comparison signal of a leakage circuit is output.
7. The leakage detection unit according to any one of claims 1 to 6, characterized in that: The signal processing circuit comprises: A signal extraction module, used for extracting the comparison signal; A filtering module, used for filtering the comparison signal; A comparison module, used for comparing the comparison signal with a preset signal threshold; The driving module is used to receive the comparison result of the comparison module and perform actions according to the comparison result.
8. The leakage detection unit according to claim 7, characterized in that: When the current vector sum of the first mutual inductance signal and the second mutual inductance signal is greater than the preset signal threshold, the driving module drives the release to operate; when the current vector sum of the first mutual inductance signal and the second mutual inductance signal is less than or equal to the preset signal threshold, the driving module maintains the current state.
9. A circuit breaker, characterized in that: include: Power module; A main circuit, electrically connected to the power module; The leakage detection unit according to any one of claims 1 to 8, electrically connected to both the main circuit and the power module; The release is connected to the main circuit and the output end of the signal processing circuit.
10. The circuit breaker according to claim 9, characterized in that The circuit breaker further comprises a button detection circuit, which is electrically connected to both the leakage detection unit and the main circuit and is used for simulating leakage current.