Electric leakage detection unit and circuit breaker
By using at least two current transformers and a differential comparator circuit in the circuit breaker, the problem of difficult assembly caused by multiple wires passing through the magnetic ring is solved, resulting in lower assembly difficulty and higher versatility of current transformers, thus ensuring circuit safety.
Patent Information
- Application Number
- CN202520399270.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-07
- Publication Date
- 2026-02-03
- Estimated Expiration
- 2035-03-07
AI Technical Summary
In existing technologies, the magnetic testing of multi-pole products involves multiple wires inserted into the magnetic ring, resulting in high process requirements, difficult assembly, and small electrical clearances.
At least two current transformers are used, each of which passes through a portion of the conductor. A differential comparison circuit and a signal processing circuit are used to determine the leakage current by comparing the signals and then drive the trip unit to operate.
It reduces the size requirements of current transformers, simplifies assembly, improves the flexibility of conductor distribution and the versatility of current transformers, avoids frequent tripping of the trip unit due to small current leakage, and ensures circuit safety.
Smart Images
Figure CN223872031U_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of low-voltage electrical technology, and in particular to a leakage current detection unit and a circuit breaker. Background Technology
[0002] A residual current circuit breaker (RCCB) is a safety protection device used in electrical systems. It can detect leakage current in a circuit and quickly disconnect the circuit when current leakage or imbalance occurs, preventing electric shock or electrical fire. In related technologies, multi-pole products require multiple wires to be inserted inside a magnetic ring to achieve leakage current detection. The shape and length of these multiple wires are affected by the position of the magnetic ring, resulting in high process requirements, difficult assembly, and small electrical clearances. Utility Model Content
[0003] In view of this, this application provides a leakage current detection unit and circuit breaker to improve the problem of difficult assembly caused by the method of detecting leakage current by inserting wires through a magnetic ring.
[0004] The technical solution adopted in this application to solve the above-mentioned technical problems is as follows:
[0005] In a first aspect, embodiments of this application provide a leakage current detection unit, comprising:
[0006] Multiple conductors of the low-voltage circuit to be protected;
[0007] At least two current transformers, a portion of the conductors of the plurality of said conductors pass through the core of one current transformer for outputting a first mutual inductance signal, and another portion of the conductors pass through the core of another current transformer for outputting a second mutual inductance signal;
[0008] A differential comparator circuit, wherein the input terminals of the differential comparator circuit are electrically connected to the secondary windings of the two current transformers respectively, for comparing the first mutual inductance signal and the second mutual inductance signal, and outputting a comparison signal;
[0009] The signal processing circuit has its input terminal electrically connected to the output terminal of the differential comparator circuit, and its output terminal electrically connected to the trip unit.
[0010] In some embodiments of this application, the number of 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 this application, the plurality of conductors include L1 line, L2 line, L3 line and N line, two of the L1 line, L2 line, L3 line and N line pass through one of the current transformers, and the other two conductors pass through the other current transformer.
[0012] In some embodiments of this application, the first mutual inductance signal is the vector sum of currents passing through the conductors of one of the current transformers; the second mutual inductance signal is the vector sum of currents passing through the conductors of the other current transformer.
[0013] In some embodiments of this application, the comparison signal is the current vector sum of the first mutual inductance signal and the second mutual inductance signal.
[0014] In some embodiments of this 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 normal operation of the output circuit is generated; 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 leakage current in the output circuit is generated.
[0015] In some embodiments of this application, the signal processing circuit includes:
[0016] A signal extraction module is used to extract the comparison signal;
[0017] A filtering module is used to filter the comparison signal;
[0018] The comparison module is used to compare the comparison signal with a preset signal threshold.
[0019] The driving module is used to receive the comparison result from the comparison module and perform actions based on the comparison result.
[0020] In some embodiments of this application, when the sum of the current vectors of the first mutual inductance signal and the second mutual inductance signal is greater than the preset signal threshold, the driving module drives the trip unit to operate; when the sum of the current vectors 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] Secondly, this application provides a circuit breaker, comprising:
[0022] Power module;
[0023] The main circuit is electrically connected to the power module;
[0024] The leakage current detection unit as described in the first aspect is electrically connected to both the main circuit and the power module;
[0025] The trip unit is connected to the output of the main circuit and the signal processing circuit.
[0026] In some embodiments of this application, the circuit breaker further includes a button detection circuit, which is electrically connected to both the leakage current detection unit and the main circuit to simulate leakage current.
[0027] In summary, due to the adoption of the above technical solution, this application includes at least the following beneficial effects:
[0028] This application provides a leakage current detection unit and circuit breaker. By setting at least two current transformers, with each current transformer having a portion of the conductor passing through it, compared to using a single current transformer passing through all conductors, the current transformer size requirements are lower, the difficulty of the conductor passing through the magnetic core of the current transformer is reduced, the assembly difficulty is lower, and the distribution of multiple conductors is more flexible. This flexible distribution of conductor positions can reduce conductor length, volume, and differences between multiple conductors. The standardized inner diameter of the current transformer also improves the versatility of current transformers between single-phase and three-phase products. Then, a differential comparison circuit is used to compare and integrate the mutual inductance signals output by multiple current transformers to generate a comparison signal. From the comparison signal, it can be determined whether there is leakage current in the circuit of the current circuit breaker. The signal processing circuit then processes the comparison signal to determine whether the trip unit is activated or not. Attached Figure Description
[0029] Figure 1 A schematic diagram of the structure of a leakage current detection unit provided for an embodiment of this application;
[0030] Figure 2 A structural block diagram of a circuit breaker provided for an embodiment of this application.
[0031] Explanation of reference numerals in the attached figures:
[0032] 1. Circuit transformer; 2. Conductor and power supply module; 3. Main circuit; 4. Leakage detection unit; 5. Conductor; 6. Current transformer; 7. Differential comparison circuit; 8. Signal processing circuit; 9. Signal extraction module; 10. Filtering module; 11. Comparison module; 12. Drive module; 13. Trip unit; 14. Button detection circuit. Detailed Implementation
[0033] The technical solutions in the embodiments of this application will now be described with reference to the accompanying drawings.
[0034] In the description of this application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or specifying the number of technical features indicated. Therefore, features defined with "first" and "second" may explicitly or implicitly include one or more features. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.
[0035] In this application, the term "exemplary" is used to mean "used as an example, illustration, or illustration." Any embodiment described as "exemplary" in this application is not necessarily to be construed as being more preferred or advantageous than other embodiments.
[0036] Please see Figure 2 This application provides a circuit breaker including a power module, a main circuit, a leakage current detection unit, and a trip unit. The power module is electrically connected to both the main circuit and the leakage current detection unit to provide power. The main circuit is primarily used to connect external devices, cooperating with other structures of the circuit breaker to achieve the switching of external devices. The leakage current detection unit is also electrically connected to the main circuit, enabling it to detect the current in the main circuit and promptly identify leakage. The trip unit is connected to the output terminals of the signal processing circuits in the main circuit and the leakage current detection unit, and is mainly used to trip based on the drive signal output from the signal processing circuits to disconnect the main circuit.
[0037] Furthermore, the circuit breaker also includes a button detection circuit, which is electrically connected to both the leakage current detection unit and the main circuit to simulate leakage current. For example, during the testing phase, to test whether the circuit breaker can accurately operate and disconnect the main circuit under leakage conditions, a leakage current is provided to the main circuit using the button detection circuit. When the leakage current detection unit detects this simulated leakage current, and the current value exceeds a preset safety threshold, it will drive the trip unit to disconnect the main circuit, ensuring circuit safety and preventing damage to the circuit breaker.
[0038] In some embodiments, see Figure 1 The leakage current detection unit includes at least two current transformers 1, multiple conductors 2 carrying the low-voltage current to be protected, a differential comparison circuit, and a signal processing circuit. The multiple conductors 2 carrying the low-voltage current to be protected are primarily used to connect to the main circuit. A portion of the conductors 2 pass through the core of one current transformer 1 to output a first mutual inductance signal, while another portion passes through the core of the other current transformer 1 to output a second mutual inductance signal. It should be noted that the first mutual inductance signal refers to the vector sum of the currents passing through the conductors 2 of one current transformer 1, and the second mutual inductance signal refers to the vector sum of the currents passing through the conductors 2 of the other current transformer 1. The input terminals of the differential comparison circuit are electrically connected to the secondary windings of the two current transformers 1, respectively, to compare the first and second mutual inductance signals and output a comparison signal. The input terminal of the signal processing circuit is electrically connected to the output terminal of the differential comparison circuit, and the output terminal is electrically connected to the trip unit.
[0039] The technical solution provided in this application uses at least two current transformers 1, with each current transformer 1 containing a portion of a conductor 2. Compared to using a single current transformer 1 that passes through all conductors 2, this method has lower size requirements for the current transformers 1, reduces the difficulty of the conductor 2 passing through the magnetic core of the current transformer 1, simplifies assembly, and allows for more flexible distribution of the conductors 2. This flexible distribution of conductors 2 reduces their length, volume, and differences between them. Then, a differential comparison circuit is used to compare and integrate the inductance signals output by the multiple current transformers 1 to generate a comparison signal. This comparison signal indicates whether leakage current exists in the circuit of the current circuit breaker. The signal processing circuit then further processes the comparison signal to determine whether the trip unit should be activated or not.
[0040] For example, this main circuit adopts a three-phase four-wire system, that is, multiple conductors 2 are referred to as four conductors 2. The conductors 2 can be conductive plates, wires, etc., and in this embodiment, wires are used. The four conductors 2 are L1 line, L2 line, L3 line and N line. Two of the L1 line, L2 line, L3 line and N line pass through one current transformer 1, and the other two conductors 2 pass through the other current transformer 1. There are two current transformers 1, and two conductors 2 pass through each current transformer 1. The two current transformers 1 are connected in parallel so that the current detected by the two current transformers 1 is relatively independent, which facilitates the calculation of the current vector sum. Distributing the four conductors 2 evenly among the two current transformers 1 helps to simplify the calculation and judgment of the current vector sum, and enables the leakage current detection unit to adapt to two-pole or multi-pole circuit leakage current detection, such as two-pole or four-pole leakage current detection.
[0041] In one embodiment, one current transformer 1 has L1 and L2 wires running through it, and the other current transformer 1 has L3 and N wires running through it. In another embodiment, one current transformer 1 has L1 and L3 wires running through it, and the other current transformer 1 has L2 and N wires running through it. In yet another embodiment, one current transformer 1 has L3 and L2 wires running through it, and the other current transformer 1 has L1 and N wires running through it.
[0042] In some embodiments, the two current transformers 1 may have one current transformer 1 with three conductors 2 running through it, while the other current transformer 1 has only one conductor 2 running through it. In one example, one current transformer 1 has L1, L2, and L3 wires running through it, while the other current transformer 1 has the N wire running through it. In another example, one current transformer 1 has L1, L2, and N wires running through it, while the other current transformer 1 has the L3 wire running through it. That is, as long as one current transformer 1 has three conductors 2 running through it, and the other current transformer 1 has only one conductor 2 running through it, it is sufficient. Since this technical solution requires calculating the vector sum of the currents detected by the two current transformers 1, it is not limited whether the two current transformers 1 are connected to live wires or neutral wires, as long as different conductors 2 are used in the two current transformers 1.
[0043] In some embodiments, the number of current transformers 1 can be three or more, and the number of conductors 2 can be four or more, depending on the actual situation.
[0044] By passing all conductors 2 through a single current transformer 1, the method is improved by grouping all conductors 2, then passing each group of conductors 2 through a corresponding current transformer 1, and then summing the current vectors of multiple groups of conductors 2. This not only enables leakage current detection but also reduces the inner diameter that each current transformer 1 needs to pass through the conductor 2, increases electrical clearance, reduces the installation difficulty of conductors 2 and current transformer 1, makes the distribution of conductors 2 more flexible, and helps to shorten the length of conductors 2.
[0045] In some embodiments, a differential comparator circuit is used to compare a first mutual inductance signal and a second mutual inductance signal, and outputs a comparison signal. This comparison signal is the vector sum of the currents of the first and second mutual inductance signals. By obtaining the comparison signal, and determining whether the comparison signal is 0 (i.e., whether the vector sum of the currents of the first and second mutual inductance signals is 0), it is determined whether there is leakage current in the current main circuit.
[0046] For example, when the current vector sum of the first mutual inductance signal and the second mutual inductance signal is equal to 0, the output circuit outputs a normal comparison signal; when the current vector sum of the first mutual inductance signal and the second mutual inductance signal is not equal to 0, the output circuit outputs a leakage comparison signal.
[0047] In one example, the secondary winding of one current transformer 1 outputs a first mutual inductance signal, and the secondary winding of the other current transformer 1 outputs a second mutual inductance signal. The two signals are vector-superimposed through a differential comparator circuit. Understandably, when the vector sum of the first and second mutual inductance signals equals 0, it indicates that there is no current leakage in conductor 2. If the vector sum of the first and second mutual inductance signals is not equal to 0, it indicates that there is current leakage in at least one conductor 2 circuit, such as leakage current from line L1 to ground, leakage current from line L2 to ground, 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 a 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; and the driving module is used to receive the comparison result from the comparison module and perform actions based on the comparison result.
[0049] For example, the signal extraction module employs a high input impedance differential amplifier, with its positive and negative input terminals connected to the two output signals of the differential comparator circuit, respectively. The amplifier gain is set to 10, and a first-order RC high-pass filter network consisting of resistors and capacitors is connected in series at the output terminal to eliminate DC bias voltage and extract AC leakage signals. This module amplifies the microvolt-level transformer output signal to the volt level while maintaining a common-mode rejection ratio (CMRR) ≥ 80dB. The filtering module uses a second-order Butterworth low-pass filter, which can effectively filter out power frequency harmonics and high-frequency switching noise, improving the signal-to-noise ratio. The comparator module adopts a window comparator structure, containing two high-speed comparator chips. The first comparator sets a positive threshold Vref_high, and the second comparator sets a negative threshold Vref_low. When the filtered signal exceeds the range [Vref_low, Vref_high], the comparator outputs a high-level pulse signal. To adapt to different application scenarios, the threshold voltage is dynamically adjusted via 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 from the comparator module, and the output drives the MOSFET to conduct, energizing the trip coil and generating magnetic force to actuate the mechanical trip mechanism. To enhance drive reliability, an RC snubber circuit is connected in series with the MOSFET gate, which can control the trip response time to within 20ms.
[0050] Furthermore, when the sum of the current vectors of the first and second mutual inductance signals is greater than a preset signal threshold, the drive module drives the trip unit to operate; when the sum of the current vectors of the first and second mutual inductance signals is less than or equal to the preset signal threshold, the drive module maintains the current state. By setting a signal processing circuit with a comparison module after the differential comparator circuit, the trip unit is prevented from frequently tripping due to small current leakage, which is detrimental to the stable operation of electrical equipment. Specifically, the technical solution provided in this application does not immediately drive the trip unit to trip upon detecting current leakage in the differential comparator circuit. Instead, it requires a specific comparison and judgment of the current leakage, that is, comparing the detected current vector sum with a preset signal threshold. If it exceeds the threshold, it is determined that the current leakage may endanger circuit safety, and the drive module can then drive the trip unit to trip. If, although current leakage is detected, it does not exceed the threshold, it means that the current leakage has no impact on current safety, and the trip unit is not driven to trip, thus avoiding the circuit breaker becoming overly sensitive and tripping frequently during use.
[0051] Furthermore, this application uses specific terms to describe embodiments of the application. For example, "an embodiment," "one embodiment," and / or "some embodiments" refer to a particular feature, structure, or characteristic associated with at least one embodiment of the application. Therefore, it should be emphasized and noted that "an embodiment," "one embodiment," or "an alternative embodiment" mentioned twice or more in different locations in this specification do not necessarily refer to the same embodiment. In addition, certain features, structures, or characteristics in one or more embodiments of the application can be appropriately combined.
[0052] Similarly, it should be noted that, in order to simplify the description of the embodiments of this application and thus aid in the understanding of one or more embodiments, the foregoing description of the embodiments of this application sometimes combines multiple features into a single embodiment, drawing, or description thereof. However, this disclosure method does not imply that the subject matter of this application requires more features than those mentioned in the claims. In fact, the embodiments contain fewer features than all the features of the single embodiments disclosed above.
Claims
1. A leakage current detection unit, characterized in that, include: Multiple conductors of the low-voltage circuit to be protected; At least two current transformers, a portion of the conductors of the plurality of said conductors pass through the core of one current transformer for outputting a first mutual inductance signal, and another portion of the conductors pass through the core of another current transformer for outputting a second mutual inductance signal; A differential comparator circuit, wherein the input terminals of the differential comparator circuit are electrically connected to the secondary windings of the two current transformers respectively, for comparing the first mutual inductance signal and the second mutual inductance signal, and outputting a comparison signal; The signal processing circuit has its input terminal electrically connected to the output terminal of the differential comparator circuit, and its output terminal electrically connected to the trip unit.
2. The leakage current detection unit as described in claim 1, characterized in that, The number of 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 current detection unit as described in claim 2, characterized in that, The plurality of conductors include L1 line, L2 line, L3 line and N line, two of the L1 line, L2 line, L3 line and N line pass through one of the current transformers and the other two conductors pass through the other current transformer.
4. The leakage current detection unit as described in claim 1, characterized in that, The first mutual inductance signal is the vector sum of the currents passing through the conductors of one of the current transformers; the second mutual inductance signal is the vector sum of the currents passing through the conductors of the other current transformer.
5. The leakage current detection unit as described in claim 4, characterized in that, The comparison signal is the current vector sum of the first mutual inductance signal and the second mutual inductance signal.
6. The leakage current detection unit as described in 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, the output circuit outputs a normal comparison signal; when the current vector sum of the first mutual inductance signal and the second mutual inductance signal is not equal to 0, the output circuit outputs a leakage comparison signal.
7. The leakage current detection unit as described in any one of claims 1 to 6, characterized in that, The signal processing circuit includes: A signal extraction module is used to extract the comparison signal; A 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 from the comparison module and perform actions based on the comparison result.
8. The leakage current detection unit as described in claim 7, characterized in that, When the sum of the current vectors of the first mutual inductance signal and the second mutual inductance signal is greater than the preset signal threshold, the drive module drives the trip unit to operate; when the sum of the current vectors of the first mutual inductance signal and the second mutual inductance signal is less than or equal to the preset signal threshold, the drive module maintains the current state.
9. A circuit breaker, characterized in that, include: Power module; The main circuit is electrically connected to the power module; The leakage current detection unit as described in any one of claims 1 to 8 is electrically connected to both the main circuit and the power supply module; The trip unit is connected to the output of the main circuit and the signal processing circuit.
10. The circuit breaker as claimed in claim 9, characterized in that, The circuit breaker also includes a button detection circuit, which is electrically connected to both the leakage current detection unit and the main circuit, and is used to simulate leakage current.