Circuit breaker impulse trip screening method and apparatus

Abstract

The application provides a circuit breaker anti-impact tripping screening method and device, the circuit breaker anti-impact tripping screening method comprises the following steps: obtaining the starting current value curve of a measured device at different time points; obtaining the maximum starting current value curve of the measured device by comparison of the starting current curve of the measured device at different time points; obtaining the tripping curve of a circuit breaker; and judging whether the circuit breaker meets the requirements according to the maximum starting current value curve of the measured device and the tripping curve of the circuit breaker. The circuit breaker anti-impact tripping screening method and device provided by the application can accurately obtain the maximum starting current of a measured device by drawing the maximum starting current value curve of the measured device, so that a circuit breaker with high selection accuracy can be selected according to the maximum starting current of the measured device.

Description

Technical Field

[0001] This invention belongs to the field of electrical components, and in particular relates to a method and device for screening circuit breaker anti-impact tripping. Background Technology

[0002] The current industry practice for addressing circuit breaker maloperation caused by inrush current in existing technologies typically involves: relying on empirical values ​​derived from load characteristics (e.g., for AC asynchronous motors, the starting current is usually determined as 5-8 times the rated current); then, the circuit breaker's specifications are determined based on an estimated maximum starting current, combined with the circuit breaker's tripping characteristics and the operating environment. This approach results in low accuracy in circuit breaker selection, is limited by the quality level of each load, and makes it difficult to accurately determine the starting current for different loads. This can easily lead to unsuitable selection, causing circuit breaker maloperation or poor protection performance. Summary of the Invention

[0003] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention proposes a method and apparatus for screening circuit breaker impact tripping. This method accurately obtains the maximum starting current of the tested equipment by plotting the maximum starting current curve, thereby selecting a circuit breaker with higher accuracy based on the maximum starting current of the tested equipment.

[0004] The present invention also proposes a circuit breaker anti-impact trip screening device.

[0005] To achieve the above objectives, according to an embodiment of the first aspect of the present invention, a method for screening circuit breaker impact tripping is provided. The method includes: acquiring the starting current curves of the device under test at different time points; obtaining the maximum starting current curve of the device under test by comparing the starting current curves of the device under test at different time points; acquiring the circuit breaker tripping curve; and determining whether the circuit breaker meets the requirements based on the maximum starting current curve of the device under test and the circuit breaker tripping curve.

[0006] According to the circuit breaker impact tripping screening method of the present invention, the maximum starting current of the tested equipment is accurately obtained by plotting the maximum starting current curve of the tested equipment, thereby selecting a circuit breaker with higher accuracy based on the maximum starting current of the tested equipment.

[0007] In some examples of the present invention, obtaining the startup current curve of the device under test at different time points includes: obtaining the test start time; dividing the test start time into several first time points in half a cycle after the test start time; and obtaining the startup current curve of the device under test corresponding to each first time point.

[0008] In some examples of the present invention, the step of obtaining the startup current curve of the device under test at different time points further includes: obtaining the test start time; dividing the test start time into several first time points in half a cycle after the test start time; increasing the time interval between the several first time points by the same amount, and the increased first time points are second time points; and obtaining the startup current curve of the device under test corresponding to each second time point.

[0009] In some examples of the present invention, determining whether the circuit breaker meets the requirements based on the starting current curve of the device under test and the tripping curve of the circuit breaker includes: if the maximum starting current curve of the device under test and the tripping curve of the circuit breaker intersect in the same coordinate system, it means that the circuit breaker does not meet the requirements; if the maximum starting current curve of the device under test and the tripping curve of the circuit breaker do not intersect in the same coordinate system, it means that the circuit breaker meets the requirements.

[0010] In some examples of the present invention, obtaining the maximum starting current value curve of the device under test by comparing the starting current curves of the device under test at different time points includes: comparing the starting current curves of the device under test at different time points in the same coordinate system, and selecting the starting current value curve of the device under test with the largest peak value as the maximum starting current value curve of the device under test.

[0011] In some examples of the present invention, the method further includes: if multiple circuit breakers meet the requirements, selecting the circuit breaker whose tripping curve is closest to but does not intersect with the maximum starting current value curve of the device under test.

[0012] According to a second aspect of the present invention, a circuit breaker impulse tripping screening device is provided, comprising: a device under test; an impulse current testing and analysis device, wherein the impulse current testing and analysis device is used to acquire the starting current value curves of the device under test at different time points; further used to obtain the maximum starting current value curve of the device under test by comparing the starting current curves of the device under test at different time points; further used to acquire the circuit breaker tripping curve; and further used to determine whether the circuit breaker meets the requirements based on the maximum starting current value curve of the device under test and the circuit breaker tripping curve.

[0013] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the circuit breaker anti-impact tripping screening method provided in an embodiment of the present invention; Figure 2This is a schematic diagram of a circuit breaker impact tripping screening method provided in another embodiment of the present invention; Figure 3 This is a schematic diagram of a circuit breaker anti-impact tripping screening method provided in another embodiment of the present invention; Figure 4 This is a schematic diagram of the circuit breaker anti-impact tripping screening device provided in an embodiment of the present invention; Figure 5 This is a schematic diagram comparing the tripping curves of the circuit breaker provided in an embodiment of the present invention; Figure 6 This is a schematic diagram of the test time point division provided in the embodiment of the present invention. Detailed Implementation

[0015] To make the technical problems solved, the technical solutions, and the beneficial effects of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0016] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0017] The following is for reference. Figure 1-3 A detailed description of the circuit breaker impact tripping screening method according to embodiments of the present invention is provided.

[0018] In some embodiments, when screening circuit breakers for impact tripping, it is necessary to apply alternating current to detect the impact current of the device under test.

[0019] In some embodiments, as shown in Figure 1, the circuit breaker impact trip screening method includes the following steps: S101, obtain the starting current value curves of the device under test at different time points.

[0020] In some embodiments, to screen circuit breakers for surge tripping resistance, it is necessary to first obtain the starting current curve of the device under test. The device under test is typically a switching power supply.

[0021] In some embodiments, many devices generate instantaneous currents during startup, known as startup inrush currents, especially switching power supplies. Due to the presence of filter capacitors, the charging of these capacitors during startup is nearly short-circuited, resulting in very large instantaneous currents. Therefore, circuit breaker tripping due to startup inrush currents (i.e., tripping of the circuit breaker even when the protected device and circuit are functioning normally) is a widespread and easily overlooked problem. The primary cause of this problem is the instantaneous inrush current generated during the startup of the protected device. The key to solving this problem is to ensure that the short-time operating current of the circuit breaker reasonably avoids the instantaneous current at any point during the load startup process. On the other hand, because alternating current has sinusoidal characteristics, the startup inrush current varies at different times within each cycle. Therefore, we need to test the startup current value of the device under test and plot a curve to find the maximum startup current of the device under test.

[0022] In some embodiments, to obtain the maximum starting current curve of the device under test (DUT), it is first necessary to obtain the starting current curves of the DUT at different time points. Since alternating current has sinusoidal characteristics, the starting inrush current is different at different time points in each cycle. Therefore, we need to test the starting current values ​​of the DUT at different time points and plot the curves to find the maximum starting current curve of the DUT.

[0023] S102, obtain the maximum starting current curve of the device under test by comparing the starting current curves of the device under test at different time points.

[0024] When obtaining the starting current value curves of the device under test at different time points, it is only necessary to compare multiple sets of starting current value curves of the device under test in the same coordinate system to obtain the maximum starting current value curve of the device under test.

[0025] S103, obtain the circuit breaker tripping curve.

[0026] In some embodiments, different circuit breaker tripping curves are different. The circuit breaker tripping curve is the operating characteristic curve of the circuit breaker's instantaneous trip unit, and therefore can be obtained directly.

[0027] S104. Based on the maximum starting current curve of the tested equipment and the tripping curve of the circuit breaker, determine whether the circuit breaker meets the requirements.

[0028] In some embodiments, after obtaining the starting current curve of the device under test and the tripping curve of the circuit breaker, it can be determined whether the circuit breaker meets the requirements.

[0029] In some embodiments, the maximum starting current curve of the device under test and the tripping curve of the circuit breaker are compared on the same coordinate system. If the maximum starting current curve of the device under test and the tripping curve of the circuit breaker intersect on the same coordinate system, it means that the circuit breaker does not meet the requirements; if the maximum starting current curve of the device under test and the tripping curve of the circuit breaker do not intersect on the same coordinate system, it means that the circuit breaker meets the requirements.

[0030] In other embodiments, due to the large number of circuit breakers to choose from, multiple circuit breakers may meet the requirements. In this case, it is necessary to select the optimal circuit breaker. Therefore, in this situation, the tripping curve of the circuit breaker that meets the requirements and the maximum starting current curve of the device under test can be compared again on the same coordinate system. Then, the circuit breaker whose tripping curve is closest to the starting current curve of the device under test can be selected.

[0031] In some specific embodiments, such as Figure 5 As shown, the maximum starting current curve of the tested equipment is compared with the tripping curves of circuit breakers A, B, and C on the same coordinate system. The tripping curve of circuit breaker B intersects with the maximum starting current curve of the tested equipment, indicating that circuit breaker B does not meet the requirements. Neither the tripping curves of circuit breaker A nor the tripping curves of circuit breaker C intersect with the maximum starting current curve of the tested equipment, meaning that circuit breakers A and C both meet the requirements. Among circuit breakers A and C, the optimal circuit breaker is selected. Comparing their tripping curves, the tripping curve of circuit breaker A is closest to the maximum starting current curve of the tested equipment; therefore, circuit breaker A is the preferred choice.

[0032] In some embodiments, such as Figure 2 As shown, step S101, obtaining the starting current value curves of the device under test at different time points, further includes: S201, Get the test start time.

[0033] In some embodiments, the time when the starting current value curve is first obtained needs to be recorded as the test start time. Using the test start time as a standard, subsequent tests are performed according to the AC cycle.

[0034] S202, based on the test start time, divide the half-cycle after the test start time into several first time points.

[0035] In some embodiments, after obtaining the test start time, subsequent tests need to be performed based on the test start time. Since alternating current has sinusoidal characteristics, it is known that within half a cycle starting at any point in time, the current will experience a peak value (maximum absolute value). If we divide the half cycle starting from this arbitrary point in time into several equal parts, a point in time will appear that is infinitely close to the point corresponding to the peak value. The starting current measured at this point is infinitely close to the maximum starting current.

[0036] In some embodiments, we record the time when the AC power is turned on and the test begins as the test start time. We can divide the half-cycle after the test start time into several equal parts, and record the starting current curves corresponding to the several first time points.

[0037] In some specific embodiments, such as Figure 6 As shown, t0 is the test start time. The half cycle is then divided into several first time points, namely t1 to t10. The starting current curves are obtained when AC power is input at each time point from t0 to t10.

[0038] S203, obtain the start-up current curve of the device under test corresponding to each first time point.

[0039] In some embodiments, in step S202, we have already obtained several first time points, and the time interval between each first time point is the same. At this time, we only need to record the start-up current curve of the device under test corresponding to each first time point.

[0040] In some embodiments, by comparing the recorded starting current curves of the device under test in the same coordinate system, a curve that is infinitely close to the maximum starting current can be obtained.

[0041] In other embodiments, such as Figure 3 As shown, step S101, obtaining the starting current value curves of the device under test at different time points, further includes: S301, Get the test start time.

[0042] In some embodiments, the time when the starting current value curve is first obtained needs to be recorded as the test start time. Using the test start time as a standard, subsequent tests are performed according to the AC cycle.

[0043] S302, based on the test start time, divide the half-cycle after the test start time into several first time points.

[0044] In some embodiments, after obtaining the test start time, subsequent tests need to be performed based on the test start time. Since alternating current has sinusoidal characteristics, it is known that within half a cycle starting at any point in time, the current will experience a peak value (maximum absolute value). If we divide the half cycle starting from this arbitrary point in time into several equal parts, a point in time will appear that is infinitely close to the point corresponding to the peak value. The starting current measured at this point is infinitely close to the maximum starting current.

[0045] In some embodiments, we record the time point at which the test begins as the test start time. We can divide the half-cycle following the test start time into several equal parts, which are then divided into several first time points. We can record the starting current curves corresponding to these first time points.

[0046] S303, the time interval between several first time points is increased equally, and the increased first time point is the second time point.

[0047] In some embodiments, theoretically, testing can be performed at various first time points within half a cycle to obtain multiple startup current curves for comparison. However, in practice, under current technological conditions, it is difficult to start the load multiple times within the same current cycle. Even if integrated with an oscilloscope into a test device for automatic control, it is difficult to achieve economically due to the short time frame. In such cases, macroscopic amplification is required.

[0048] In some embodiments, the AC frequency is typically 50 Hz, i.e., the period is 1 / 50 of a second (0.02 seconds). The time between two tests can be amplified to several times the AC period T. To ensure that the device under test is fully discharged before each power-on, the time interval between two test starts needs to be more than 1 minute. The algorithm for the time interval between two test starts can be determined using the following formula: tn = t0 + n * (K1 * T + T / K2) Here, tn represents the time interval between two test initiations; t0 represents the time point of the first test initiation, i.e., the test time base point; n is the number of tests (n=0,1,2,3…); K1 is the test interval time constant, which can be set according to the estimated value of the time interval between two tests; T is the AC cycle (0.02s for domestic power frequency); K2 is the time constant for equal division of a single cycle test. Among the above parameters, t0 is the initiation time point of the first test, which is automatically triggered and generated in the test device. n, K1, K2, and T are input parameters, set according to the specific test environment and the characteristics of the device under test.

[0049] S304, obtain the starting current curve of the device under test corresponding to each second time point.

[0050] In some embodiments, different second time points are obtained in step S403, and then the start-up current curve of the device under test corresponding to each second time point is obtained.

[0051] In some embodiments, as described in step S403, the device under test is a switching power supply, where K2=10 and K1 can be 3000. For example, if the first start-up time is t0, the second start-up time is t1=t0+1*(3000*0.02+0.02 / 10)=t0+60.002s, the third start-up time is t2=t0+2*(3000*0.02+0.02 / 10)=t0+120.004s, and so on. The curves of K2 starting inrush currents can be measured, and the maximum value curve is automatically compared and selected to obtain the maximum starting current curve of the device under test.

[0052] To facilitate better implementation of the above-described solutions in the embodiments of this application, this application also provides an apparatus for implementing the above-described solutions.

[0053] like Figure 4 As shown, the circuit breaker impact tripping screening device 100 includes a device under test 10 and an impact current testing and analysis device 20. The impact current testing and analysis device 20 is used to obtain the starting current curve of the device under test; it is also used to obtain the circuit breaker tripping curve; and it is used to determine whether the circuit breaker meets the requirements based on the starting current curve of the device under test and the circuit breaker tripping curve.

[0054] In some embodiments, the impulse current test and analysis device 20 further includes an impulse current testing device 201 and a curve parameter analysis device 202. The impulse current testing device 201 is used to test the starting current value of the device under test. The curve parameter analysis device 202 is used to obtain the starting current value curve of the device under test; it is also used to obtain the circuit breaker tripping curve; and it is also used to determine whether the circuit breaker meets the requirements based on the starting current value curve of the device under test and the circuit breaker tripping curve.

[0055] In some embodiments, the curve parameter analysis device 202 is further configured to obtain the test start time; divide the test start time into several first time points in half a cycle after the test start time; and obtain the starting current value of the device under test corresponding to each first time point.

[0056] In some embodiments, the curve parameter analysis device 202 is further used to obtain the test start time; divide the test start time into several first time points in half a cycle after the test start time; amplify the several first time points by several times to obtain second time points; and obtain the starting current value of the device under test corresponding to each second time point.

[0057] In some specific embodiments, the AC frequency is typically 50 Hz, i.e., the period is 1 / 50 of a second (0.02 seconds). The time between two tests can be amplified to several times the AC period T. To ensure that the device under test is fully discharged before each power-on, the time interval between two test starts needs to be more than 1 minute. The algorithm for the time interval between two test starts can be determined using the following formula: tn = t0 + n * (K1 * T + T / K2) Here, tn represents the time interval between two test initiations; t0 represents the time point of the first test initiation, i.e., the test time base point; n is the number of tests (n=0,1,2,3…); K1 is the test interval time constant, which can be set according to the estimated value of the time interval between two tests; T is the AC cycle (0.02s for domestic power frequency); K2 is the time constant for equal division of a single cycle test. Among the above parameters, t0 is the initiation time point of the first test, which is automatically triggered and generated in the test device. n, K1, K2, and T are input parameters, set according to the specific test environment and the characteristics of the device under test.

[0058] The above algorithm is integrated into the curve parameter analysis device 202, and the circuit breaker tripping curve is imported into the curve parameter analysis device 202. This allows the curve parameter analysis device 202 to compare the maximum starting current curve of the tested equipment with the circuit breaker tripping curve, thereby selecting the most suitable circuit breaker.

[0059] Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium. When executed, the computer program can include the processes of the embodiments of the above methods. Any references to memory, storage, databases, or other media used in the embodiments provided in this application can include non-volatile and / or volatile memory. Non-volatile memory may include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory may include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in a variety of forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), dual data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), RAMbus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), etc.

[0060] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional units and modules is used as an example. In practical applications, the above functions can be assigned to different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above.

[0061] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

[0062] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0063] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A method for screening circuit breaker impact-resistant tripping, characterized in that, include: Obtain the starting current curves of the device under test at different time points; The maximum starting current curve of the device under test is obtained by comparing the starting current curves of the device under test at different time points; Obtain the circuit breaker tripping curve; Based on the maximum starting current curve of the tested equipment and the tripping curve of the circuit breaker, determine whether the circuit breaker meets the requirements; The step of determining whether the circuit breaker meets the requirements based on the starting current curve of the tested equipment and the tripping curve of the circuit breaker includes: If the maximum starting current curve of the tested device and the tripping curve of the circuit breaker intersect in the same coordinate system, it means that the circuit breaker does not meet the requirements. If the maximum starting current curve of the tested device and the tripping curve of the circuit breaker do not intersect in the same coordinate system, it means that the circuit breaker meets the requirements.

2. The circuit breaker impact tripping screening method according to claim 1, characterized in that, The acquisition of the startup current curves of the device under test at different time points includes: Get the test start time; Based on the test start time, the test start time is divided into several first time points in half a cycle after the test start time; Obtain the startup current curve of the device under test corresponding to each first time point.

3. The circuit breaker impact tripping screening method according to claim 1, characterized in that, The acquisition of the startup current curves of the device under test at different time points includes: Get the test start time; Based on the test start time, the test start time is divided into several first time points in half a cycle after the test start time; Increase the time interval between several first time points by the same amount, and the increased first time point is the second time point; Obtain the startup current curve of the device under test corresponding to each second time point.

4. The circuit breaker impact tripping screening method according to claim 1, characterized in that, The step of obtaining the maximum starting current curve of the device under test by comparing the starting current curves of the device under test at different time points includes: The starting current curves of the device under test at different time points are compared in the same coordinate system, and the starting current value curve of the device under test with the largest peak value is selected as the maximum starting current value curve of the device under test.

5. The circuit breaker impact tripping screening method according to claim 1, characterized in that, Also includes: If multiple circuit breakers meet the requirements, select the circuit breaker whose tripping curve is closest to, but does not intersect with, the maximum starting current curve of the tested equipment.

6. A circuit breaker impact-resistant tripping screening device, characterized in that, include: The device under test; An impulse current testing and analysis device is used to acquire the starting current value curves of the device under test at different time points; it is also used to obtain the maximum starting current value curve of the device under test by comparing the starting current curves of the device under test at different time points; it is also used to acquire the circuit breaker tripping curve; and it is also used to determine whether the circuit breaker meets the requirements based on the maximum starting current value curve of the device under test and the circuit breaker tripping curve. The step of determining whether the circuit breaker meets the requirements based on the starting current curve of the tested equipment and the tripping curve of the circuit breaker includes: if the maximum starting current curve of the tested equipment and the tripping curve of the circuit breaker intersect in the same coordinate system, it means that the circuit breaker does not meet the requirements. If the maximum starting current curve of the tested device and the tripping curve of the circuit breaker do not intersect in the same coordinate system, it means that the circuit breaker meets the requirements.

7. The circuit breaker impact-resistant tripping screening device according to claim 6, characterized in that, The impulse current testing and analysis device includes: An impulse current testing device, wherein the impulse current testing device is used to test the starting current value of the device under test; The curve parameter analysis device is used to obtain the starting current value curve of the device under test at different time points; it is also used to obtain the maximum starting current value curve of the device under test by comparing the starting current curves of the device under test at different time points; it is also used to obtain the circuit breaker tripping curve; and it is also used to determine whether the circuit breaker meets the requirements based on the maximum starting current value curve of the device under test and the circuit breaker tripping curve.

8. The circuit breaker impact-resistant tripping screening device according to claim 7, characterized in that, The curve parameter analysis device is also used to obtain the test start time; based on the test start time, the test start time is divided into several first time points in half a cycle; and the starting current value of the device under test corresponding to each first time point is obtained.

9. The circuit breaker impact-resistant tripping screening device according to claim 7, characterized in that, The curve parameter analysis device is also used to obtain the test start time; based on the test start time, the test start time is divided into several first time points in half a cycle; the several first time points are magnified by several times to obtain second time points; and the starting current value of the device under test corresponding to each second time point is obtained.

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