Current testing device and testing method

Abstract

The invention discloses a current test device and test method, and belongs to the technical field of current test equipment, the current test device comprises a power output unit and a control unit, the power output unit is used for outputting test current; the control unit is electrically connected with the power output unit and is used for controlling output parameters of the test current; the power output unit comprises a first power adjusting unit and a second power adjusting unit. The first power adjusting unit is configured to respond to a first instruction of the control unit and adjust the output test current to different preset current intervals; the second power adjusting unit is configured to respond to a second instruction of the control unit and adjust the testing current in the preset current interval to a target value, the current testing device can achieve continuous adjustable output from small current to large current, the current testing device is suitable for tested devices of different types and specifications (such as single-phase and multi-phase circuit breakers), and the testing efficiency is improved. Test elements do not need to be replaced, and adaptation difficulty is reduced.

Description

Technical Field

[0001] This application relates to current testing equipment technology, and more particularly to a current testing device and testing method. Background Technology

[0002] With the development of power systems, electrified transportation, industrial automation and new energy equipment, the rated current and switching capacity of electrical switchgear and power electronic devices are constantly improving. Testing their performance indicators, such as high current, long time, repeatability and over-limit tripping time, has become an important part of ensuring their safe and reliable operation.

[0003] Currently, there are some high-current testing systems on the market. However, these systems are not adaptable to different load specifications and current output intensities, and still have certain limitations. Summary of the Invention

[0004] This application provides a current testing device and testing method to solve the problem of insufficient adaptability of current testing devices to different load specifications and different current output intensities in related technologies.

[0005] To address the aforementioned technical problems, in a first aspect, embodiments of this application provide a current testing device, comprising:

[0006] Power output unit, used to output test current;

[0007] The control unit is electrically connected to the power output unit and is used to control the output parameters of the test current;

[0008] The power output unit includes a first power adjustment unit and a second power adjustment unit connected to the first power adjustment unit;

[0009] The first power regulation unit includes at least two transformer groups connected in parallel. The first power regulation unit is configured to respond to a first command from the control unit to switch different numbers of transformer groups connected to the output circuit in stages, so as to adjust the output test current to different preset current ranges.

[0010] The second power adjustment unit includes a variable transformer with an adjustable number of primary coil turns. The second power adjustment unit is configured to adjust the number of primary coil turns of the variable transformer in response to a second command from the control unit, so as to adjust the test current in the preset current range to a target value.

[0011] In some possible implementations, it also includes:

[0012] The control power transformer is connected to an external AC power source to step down the external AC voltage to a preset voltage.

[0013] A switching power supply module is connected to the output terminal of the control power transformer to receive the preset voltage and convert the preset voltage into at least two DC regulated output voltages, which are respectively used to power the first power regulation unit and the second power regulation unit.

[0014] In some possible implementations, the first power regulation unit further includes:

[0015] At least two contactor groups, each contactor group being connected to a corresponding transformer group; the secondary windings of at least two transformer groups being connected in parallel, and the main contacts of each contactor group being connected in series to the output circuit of the corresponding transformer group; the contactor groups are used to regulate the connection status between the corresponding transformer group and the circuit where the test current is located.

[0016] A relay group, connected to the contactor group, is used to drive the contactor group to operate;

[0017] The control unit is connected to at least two of the relay groups. The control unit is used to regulate the on / off state of the contactor group through the relay group to form at least two transformer groups into different numbers of parallel circuits. The parallel circuits correspond one-to-one with the preset current range.

[0018] In some possible implementations, the variable transformer has brushes on its regulating shaft, and the second power regulating unit further includes a drive motor connected to the control unit. The drive motor is configured to be controlled by the control unit to drive the regulating shaft to rotate, thereby causing the brushes to slide on the winding surface of the primary coil. The sliding brushes adjust the effective number of turns of the primary coil connected to the output circuit.

[0019] In some possible implementations, the control unit is configured to:

[0020] Determine the target value and current value of the test current;

[0021] Based on the difference between the target value and the current value, a second instruction is generated to control the rotation direction and rotation angle of the drive motor, and the test current after the drive motor is activated is adjusted from the current value to the target value.

[0022] In some possible implementations, a contactor interlock circuit is also included, which is connected to at least two of the contactor groups. The contactor interlock circuit is configured such that when the first power regulating unit performs a gear switching operation, the contactor in the current parallel circuit is in a different engaging state than the contactors in the other parallel circuits.

[0023] In some possible implementations, the transformer bank has four sets arranged in parallel, and the contactor sets are arranged corresponding to the transformer bank.

[0024] In some possible implementations, the system also includes a housing and a control box disposed on the housing, wherein the first power regulation unit, the second power regulation unit, the control power transformer and the switching power supply module are all disposed in the housing, and the control unit is disposed in the control box.

[0025] On the other hand, this application provides a testing method applicable to the current testing device described in any of the above claims, the testing method comprising:

[0026] Receives external test current;

[0027] Generate a first instruction to control the number of at least two parallel transformer groups connected to the output circuit, so as to coarsely adjust the test current to a preset current range;

[0028] A second instruction is generated to adjust the number of turns in the primary coil of the variable transformer to fine-tune the test current within the preset current range to the target value;

[0029] The target value of the test current is output to the external device under test.

[0030] In some possible implementations, it also includes:

[0031] The output state of the test current and the test state of the device under test are detected under a preset sampling period.

[0032] In response to any abnormality in the output state and the test state, the abnormal value of the test current at the time of the abnormality is recorded and the output of the test current is stopped.

[0033] In summary, the current testing device provided in this application embodiment, by setting a first power adjustment unit, coarsely adjusts the test current by switching parallel transformer groups in stages, thereby achieving a large span and step-like coverage of the output current. The second power adjustment unit finely adjusts the test current by adjusting the number of turns of a variable transformer. Within the preset current range determined by the coarse adjustment, continuous and smooth fine adjustment is performed, which is conducive to achieving wide-range and high-precision current adjustment, reducing testing difficulty, and improving testing efficiency.

[0034] Furthermore, since the output test current can be continuously adjusted within a wide range, the current testing device can be adapted to devices of different specifications and current levels without changing the internal hardware, achieving dynamic load adaptation and strong versatility. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 This is a schematic diagram of the overall structure of the current testing device in the embodiments of this application;

[0037] Figure 2 This is a schematic diagram of the overall structure of the current testing device from another angle in an embodiment of this application;

[0038] Figure 3 This is a partial enlarged view of the current testing device in the embodiments of this application;

[0039] Figure 4 This is a schematic diagram of the parallel connection of multiple transformer groups in an embodiment of this application. Detailed Implementation

[0040] This application provides a current testing device and testing method to solve the problem of insufficient adaptability of current testing devices to different load specifications and different current output intensities in related technologies.

[0041] With the development of power systems, electrified transportation, industrial automation, and new energy equipment, the rated current and breaking capacity of electrical switchgear and power electronic devices are constantly increasing. Testing their performance indicators, such as high current, long-term operation, repeatability, and over-limit tripping time, has become a crucial step in ensuring their safe and reliable operation. In the manufacturing and maintenance of circuit breakers, tests are required on overload capacity, operating time, temperature rise, and durability. Meanwhile, in the production and verification of power semiconductor devices, rated or even short-time limiting currents are applied to verify their conductivity and thermal characteristics.

[0042] Currently, some high-current testing systems exist on the market, including Rogowski coil test circuits and dual-sampling resistor test circuits. However, the Rogowski coil test circuit has a low-frequency measurement limit of only about 15Hz, relies on complex signal processing, and is susceptible to noise interference. The dual-sampling resistor test circuit's dynamic switching may introduce errors, and accuracy decreases when switching between low and high currents. Therefore, current testing systems suffer from insufficient low-frequency response and measurement accuracy, and there is still room for improvement in adapting to different load specifications, current output intensities, and enhancing low-frequency response capabilities.

[0043] Based on this, one or more embodiments of this application provide a current testing device and a testing method. In the current testing device, a first power adjustment unit is set up. The first power adjustment unit coarsely adjusts the test current by switching the parallel transformer group in stages, realizing a large span and step-like coverage of the output current. The second power adjustment unit finely adjusts the test current by adjusting the number of turns of the variable transformer. Continuous and smooth fine adjustment is performed within the preset current range determined by the coarse adjustment, which is conducive to realizing wide-range and high-precision current adjustment, reducing testing difficulty, and improving testing efficiency.

[0044] Furthermore, since the output test current can be continuously adjusted within a wide range, the current testing device can be adapted to devices of different specifications and current levels without changing the internal hardware, achieving dynamic load adaptation and strong versatility.

[0045] The following description, in conjunction with the accompanying drawings, illustrates the solutions of the embodiments of this application.

[0046] like Figures 1 to 4 As shown, the current testing device of this application embodiment includes a power output unit and a control unit.

[0047] The power output unit is used to output a test current; the control unit is electrically connected to the power output unit and is used to control the output parameters of the test current; the power output unit includes a first power adjustment unit and a second power adjustment unit connected to the first power adjustment unit.

[0048] The first power regulation unit includes at least two transformer groups 110 connected in parallel. The first power regulation unit is configured to switch different numbers of transformer groups 110 connected to the output circuit in response to a first command from the control unit, so as to adjust the output test current to different preset current ranges.

[0049] The second power adjustment unit includes a variable transformer 140 with an adjustable number of primary coil turns. The second power adjustment unit is configured to adjust the number of primary coil turns of the variable transformer 140 in response to a second command from the control unit, so as to adjust the test current in the preset current range to a target value.

[0050] As can be seen from the above description, the current testing device of this application embodiment, by setting a first power adjustment unit, coarsely adjusts the test current by switching the parallel transformer group 110 in stages, realizing a large span and step-like coverage of the output current. The second power adjustment unit finely adjusts the test current by adjusting the number of turns of the variable transformer 140. Continuous and smooth fine adjustment is performed within the preset current range determined by the coarse adjustment, which is conducive to realizing wide-range and high-precision current adjustment, reducing testing difficulty and improving testing efficiency.

[0051] like Figure 2 As shown, in some embodiments, the first power regulation unit further includes:

[0052] At least two contactor groups 120, each contactor group 120 being connected to a transformer group 110; the secondary windings of at least two transformer groups 110 being connected in parallel; the main contacts of each contactor group 120 being connected in series to the output circuit of the corresponding transformer group 110; the contactor group 120 being used to regulate the connection state between the corresponding transformer group 110 and the circuit containing the test current.

[0053] At least two relay groups 130 are provided, each corresponding to one of the contactor groups 120, and the relay groups 130 are used to drive the contactor groups 120 to operate.

[0054] The control unit is connected to at least two of the relay groups 130. The control unit is used to regulate the on / off state of the contactor group 120 through the relay group 130 to form at least two of the transformer groups 110 into different numbers of parallel circuits. The parallel circuits correspond one-to-one with the preset current range.

[0055] In the above embodiment, the secondary windings of all transformer groups 110 are connected in parallel. This design enables current superposition and expands the output capacity. When the control unit needs to increase the output current level, it sends a closing command to the corresponding contactor group 120. The main contacts of the contactor group 120 close, connecting the transformer group 110 it controls in parallel to the currently operating output circuit. Because the windings of the transformer groups 110 are connected in parallel, the newly connected transformer group 110 will provide current to the load together with the original transformer group 110, thereby achieving a step-by-step increase in the total output current. Conversely, when it is necessary to decrease the level, the control unit controls the designated contactor group 120 to open, disconnecting its corresponding transformer group 110 from the parallel circuit.

[0056] The control unit is electrically connected to the coil control terminals of all contactor groups 120. Based on the target current value set by the user, the control unit automatically determines the required current level (i.e., the preset current range) through its internal logic algorithm, and then generates the first command to precisely control the on / off state of each contactor group 120. Through this control method, different numbers of transformer groups 110 can be combined into the required parallel circuit. Each specific parallel combination, such as only one transformer group 110 working, two transformer groups 110 in parallel, or three transformer groups 110 in parallel, corresponds to a preset current range for output. Figure 4 In the middle, the two adjacent transformer groups 110 are not connected.

[0057] By designing multiple transformer groups 110 in a parallel configuration, the output current capacity is modularly and progressively increased. This eliminates the need for a single, large transformer; instead, standardized, modular medium-capacity transformers are combined, reducing manufacturing complexity and heat dissipation pressure, while also broadening the overall output range of the equipment. Furthermore, due to the parallel structure of multiple transformer groups 110, the current testing device has a wide current adjustment range by switching between different numbers of transformer groups 110, achieving adjustable current output from 100 to 100,000 amperes. Therefore, the current testing device can adapt to testing requirements at different current levels and meet application requirements under various testing conditions.

[0058] Furthermore, compared to traditional mechanical tap switches or manual operation, the contactor group 120 electrically controlled switching method driven by the control unit offers a faster response speed and enables remote control and automated process integration. The entire current regulation process, from command issuance to completion of gear switching, can be completed in a shorter time, significantly improving testing efficiency.

[0059] In some embodiments, the transformer group 110 has four groups arranged in parallel, and the contactor group 120 is arranged corresponding to the transformer group 110. The current testing device also includes a contactor interlock circuit, which is connected to at least two of the contactor groups 120. The contactor interlock circuit is configured such that when the first power regulating unit performs a range switching operation, the contactor in the current parallel circuit has a different engagement state than the contactor in other parallel circuits.

[0060] The aforementioned contactor interlock circuit is used to ensure that at any given time, at most one contactor group 120 is in the energized and conducting state. When the first power regulating unit needs to perform a gear switching action, the contactor group 120 in the current energized state must be completely disconnected before the contactor group 120 in the target gear is allowed to be energized.

[0061] For example, the interlocking function can be implemented through various mature electrical methods. For instance, the normally closed contacts of each contactor group 120 can be connected in series to the coil power supply circuit of other contactor groups 120. When one contactor group 120 is engaged, its normally closed contacts open, cutting off the coil power supply path of the other contactor groups 120, preventing them from being energized and engaged. This is merely an example in the embodiments of this application.

[0062] By setting up a contactor interlock circuit, it is possible to avoid instantaneous short circuits in the transformer parallel connection caused by the simultaneous engagement of two or more contactors, thereby preventing damage to the test equipment.

[0063] It should be noted that the control unit in this embodiment can be a pre-programmed programmable logic controller. The specific types and application methods of the programmable logic controller can be referred to the component settings in related technologies, which will not be repeated in this embodiment.

[0064] like Figure 3 As shown, in some embodiments, the variable transformer 140 has a brush 160 on its adjusting shaft 150. The second power adjustment unit also includes a drive motor 170 connected to the control unit. The drive motor 170 is configured to drive the adjusting shaft 150 to rotate under the control of the control unit, thereby causing the brush 160 to slide on the winding surface of the primary coil. The sliding brush 160 adjusts the effective number of turns of the primary coil connected to the output circuit.

[0065] The aforementioned variable transformer 140 can be a voltage regulator or an autotransformer. The primary coil of the variable transformer 140 is wound on the surface of a toroidal core, and a specific number of turns of the coil is electrically connected to the output circuit via a brush 160. The brush 160 is mounted on an adjusting shaft 150, and the position of the brush 160 on the adjusting shaft 150 determines the effective number of primary coil turns currently connected to the circuit.

[0066] The drive motor 170 serves as a power source, and its output shaft is connected to the adjustment shaft 150 of the variable transformer 140 via a coupling or gear set or other related transmission mechanism. The drive motor 170 is electrically connected to the control unit and receives a second command from the control unit. Here, the second command is generally a pulse signal or analog signal representing the direction and angle of rotation. Based on the difference between the set target current value and the actual output current feedback value, the control unit calculates the required adjustment direction and approximate angle, and then issues corresponding control commands to the drive motor 170.

[0067] The drive motor 170 rotates according to the command, driving the adjusting shaft 150 and its brushes 160 to rotate together via the transmission mechanism. The brushes 160 then slide smoothly on the winding surface of the primary coil of the variable transformer 140, thereby continuously changing the effective number of turns connected to the output circuit. Since the output voltage is proportional to the effective number of turns of the primary coil, continuous and fine adjustment of the output voltage and output current is achieved.

[0068] It should be noted that the connection method between the adjusting shaft 150 and the brush 160, and between the electric adjusting shaft and the drive motor 170, can be set with reference to relevant technologies. As long as the drive motor 170 can drive the brush 160 to move, so that the effective number of turns of the brush 160 connected to the output circuit changes accordingly, this application embodiment does not impose an absolute limitation on this.

[0069] By replacing the traditional handwheel operation with a drive motor 170, the adjustment process is automatically controlled by the control unit. This design eliminates tedious manual operation, greatly improving testing efficiency. At the same time, the fine-tuning process can form a responsive closed-loop control system with current feedback, achieving adaptive adjustment.

[0070] Furthermore, the control unit is configured to:

[0071] Determine the target value and current value of the test current;

[0072] Based on the difference between the target value and the current value, a second instruction is generated to control the rotation direction and rotation angle of the drive motor 170, and the test current after the drive motor 170 is activated is adjusted from the current value to the target value.

[0073] The control process begins with the control unit determining the target value and the current value of the test current. The target value is preset by the user through a human-machine interface, such as a touchscreen or other interactive buttons. The current value is acquired in real time by a high-precision current sampling circuit and fed back to the control unit. The current sampling circuit can employ a shunt or Hall effect sensor circuit, as described in this embodiment.

[0074] The control unit generates the second instruction based on the calculated difference. The second instruction is a set of commands that can be recognized and executed by the drive motor 170, and its content contains precise information on controlling the rotation direction and rotation angle of the drive motor 170.

[0075] The direction of rotation of drive motor 170 is determined by the sign of the difference. If the current value is lower than the target value, the motor is controlled to rotate in the direction of increasing the number of turns; conversely, it rotates in the direction of decreasing the number of turns. The rotation angle of drive motor 170 is proportional to the magnitude of the difference. The larger the difference, the greater the deviation, and the greater the adjustment required, thus requiring a larger angle of motor rotation; conversely, a small angle adjustment is made.

[0076] Upon receiving the second command, the drive motor 170 immediately activates, precisely rotating at the specified angle and direction. Through the adjusting shaft 150, it drives the brushes 160 of the variable transformer 140 to slide, changing the effective number of turns, thereby adjusting the output current from the current value to the target value.

[0077] It should be noted that the above process is a continuous, real-time, closed-loop process. The control unit continuously samples and compares the data and outputs a second command, while the drive motor 170 continuously makes fine adjustments until the difference between the current value and the target value approaches zero. This state is maintained throughout the test to counteract current disturbances caused by power grid fluctuations or load changes.

[0078] By introducing feedback of the current value and comparing it with the target value, a closed-loop control is formed. This automatically compensates for the effects of disturbances such as transformer losses, grid voltage fluctuations, or load impedance changes on the output current, thus maintaining the accuracy of the output current under most operating conditions.

[0079] In some embodiments, the current testing device further includes a control power transformer 180 and a switching power supply module 190, wherein the control power transformer 180 is connected to an external AC power source and is used to step down the external AC voltage to a preset voltage; the switching power supply module 190 is connected to the output terminal of the control power transformer 180 and is used to receive the preset voltage and convert the preset voltage into at least two DC regulated output voltages, the at least two DC regulated output voltages being used to power the first power regulation unit and the second power regulation unit, respectively.

[0080] For example, when an externally input 380V industrial AC voltage is connected to the current testing device of this application embodiment, it is first stepped down to 110V AC voltage via the control power transformer 180 to provide input voltage for the internal switching power supply module 190. The switching power supply module 190 converts the AC power into a DC regulated output, which is supplied to the first power regulation unit and the second power regulation unit respectively. After receiving power from the switching power supply module 190, the control unit starts and performs logic control on the relay group 130; the relay group 130 then drives the contactor group 120, thereby controlling the on / off state of the transformer group 110 and the variable transformer 140. At the same time, the control unit controls the drive motor 170 to operate, driving the rotating shaft inside the variable transformer 140 to adjust the effective number of turns of the primary coil connected to the output circuit.

[0081] In some embodiments, the current testing device further includes a housing 100 and a control box 200 disposed on the housing 100. The first power adjustment unit, the second power adjustment unit, the control power transformer 180 and the switching power supply module 190 are all disposed in the housing 100, and the control unit is disposed in the control box 200.

[0082] In some embodiments, an emergency stop button is provided on the housing 100, located in a prominent position on the body, allowing the operator to quickly interrupt the output circuit of the entire system at any stage, thereby achieving emergency power-off control at the physical level.

[0083] In some embodiments, an over-temperature protection mechanism is provided inside the enclosure 100. Temperature monitoring elements are arranged in heat-generating parts such as the transformer group 110 and the switching power supply module 190. The temperature detection elements are connected to the control unit. Once the temperature exceeds the set threshold, the control unit automatically terminates the test process and forcibly shuts down the output circuit, while triggering an audible and visual alarm to prompt the operator to troubleshoot the fault.

[0084] In some embodiments, the current testing device includes a high-sensitivity sampling circuit that monitors the operating signals of the device under test in real time. When a tripping event is detected, the system responds immediately, controlling the contactor to disconnect the power supply path to ensure the output current is terminated immediately. To prevent incorrect wiring or input overvoltage, the device has a main circuit breaker 191 at the input terminal and a dedicated control transformer on the power supply side for isolation and voltage reduction, while providing a safe operating voltage for each control module. The panel output has a current-limiting design and test indicator light function to provide real-time feedback on current status and on / off conditions, assisting the operator in judging the device's status.

[0085] The current testing device in this application has multiple operating modes, each suitable for different testing needs. These operating modes include normal mode, memory mode, inching-to-trip mode, inching-to-hold mode, and current holding mode. The testing methods for each of these different operating modes are described below.

[0086] Normal mode is used for general testing of the device under test.

[0087] In normal mode, the device defaults to a standby state, and operators can choose between normal start or jog start depending on the specific application. When normal start is selected, the system will automatically complete a full test cycle according to the user-defined output current, current duration, and number of cycles, suitable for high-volume testing needs in automated scenarios. When jog start is selected, the user can test the actual current value that the system can output. The system outputs current immediately upon receiving the jog start signal, and the power-on process remains effective until a trip is detected, the maximum test time is reached, or it is terminated by manual intervention.

[0088] In this mode, by selecting normal startup, users can test parameters such as overload long delay, short circuit short delay, short circuit instantaneous delay, and grounding protection of the device under test. Here, the device under test is a circuit breaker, which will not be described further in the following embodiments of this application.

[0089] During overload long-delay testing, the purpose is to test whether the device under test (DUT) can withstand an overload current for a sufficient period of time and whether it will trip within the longest overload period to protect the device. After the test is started, the system continuously reads the output current at 100ms intervals after the output is connected, while comprehensively monitoring the status of the DUT during the test, including whether an emergency stop command is triggered, whether an abnormal temperature occurs, and whether a trip is detected. If a valid trip is detected within the set time limit (usually 15s, which can be set according to the specific parameters of the circuit breaker), the system immediately cuts off the power and records the relevant test data, and the test is considered successful. If timeout, over-temperature, or emergency stop occurs during the process, the test is terminated and judged as a failure.

[0090] Short - circuit short - delay time test is to test whether the device under test will trip within the specified non - over - time when carrying short - circuit current. The jog - to - trip mode is specifically used to perform the short - delay test. When the system receives the JOG signal, it immediately turns on the output, records the start time, and performs high - frequency sampling at a period of 2 ms to detect the change of the output current in real time. Once the current signal is detected, it enters the trip monitoring stage. In this stage, the current data is continuously cached, and it is judged whether the trip has occurred. If the breaker action signal is detected within the set maximum allowable test time (usually 500 ms, which can be set according to the specific parameters of the circuit breaker), the system immediately disconnects the output circuit, indicating that the test ends normally; on the contrary, if no trip is detected within the time limit, or there is no current output in the initial stage, the test is judged as failed. After the test ends, the system analyzes the sampling data, calculates the maximum output current and the total power - on duration during the test process, providing an accurate basis for the evaluation of the short - delay action performance. This mode has an extremely high response speed and can accurately capture the tripping behavior of devices such as circuit breakers under transient current impact.

[0091] The short - circuit instantaneous test is to test whether the circuit breaker will trip within the specified time when carrying several times the short - circuit current. Tests such as ground protection are to test whether the ground protection function of the circuit breaker is normal. A loop with a known resistance value or a direct short - circuit is connected between the phase line and the protective ground, and the output current of the current test device greater than the specified rated ground - fault current is connected to this loop. If the device under test trips within the specified time, it is considered qualified. The test procedures for these two tests are similar to the short - circuit short - delay test and will not be elaborated here.

[0092] The memory mode is essentially the same as the normal mode, except that the operation data of the tester is recorded during the test for further analysis.

[0093] The jog - to - trip mode can test the actual tripping current of the circuit breaker. During the test, the current test device will automatically increase the current in a JOG manner until the circuit breaker trips. Press the stop button to stop the test at any time.

[0094] The jog - to - hold mode can test whether the circuit breaker will trip when it reaches its holding current. During the test, the tester will automatically increase the current to the holding current, and this holding current can be flexibly set according to requirements. When the set value of the holding current is reached, the output is turned off to stop the test, and the current is not output continuously. If you want to continue outputting current for a long - time holding test, you can select the current - holding mode.

[0095] The current - holding mode can test whether the circuit breaker can withstand its holding current for a long time. This holding current is generally slightly higher than the rated operating current. During the test, the tester will automatically increase the current to the holding current. When the set value of the holding current is reached, the output of the tester continues to hold until the circuit breaker trips or the test is terminated.

[0096] On the other hand, this application also provides a testing method applicable to the current testing device in any of the above embodiments, the testing method comprising:

[0097] Receives external test current;

[0098] Generate a first instruction to control the number of at least two parallel transformer groups 110 connected to the output circuit, so as to coarsely adjust the test current to a preset current range;

[0099] A second instruction is generated to adjust the number of turns in the primary coil of the variable transformer 140 to fine-tune the test current within the preset current range to the target value.

[0100] The target value of the test current is output to the external device under test.

[0101] The above-described testing methods can be used in the testing steps of different working modes in the above embodiments, and will not be repeated in this application embodiment.

[0102] It should be understood that although quantifiers such as "first," "second," etc., may be used herein to describe various units, these units should not be limited by these terms. These terms are used merely to distinguish one unit from another. For example, without departing from the scope of the exemplary embodiments, a first unit may be referred to as a second unit, and similarly, a second unit may be referred to as a first unit.

[0103] The directional terms such as "outer," "middle," and "inner" mentioned or potentially used in this specification are defined relative to the structures shown in the accompanying drawings. They are relative concepts and may therefore vary depending on their location and usage. Therefore, these or other directional terms should not be interpreted as restrictive.

[0104] The above description is merely a preferred embodiment of this application and is not intended to limit this application in any form or substance. It should be noted that those skilled in the art can make various improvements and additions without departing from the method of this application, and these improvements and additions should also be considered within the scope of protection of this invention. Any modifications, alterations, and equivalent variations made by those skilled in the art without departing from the spirit and scope of this application, based on the disclosed technical content, are equivalent embodiments of this application. Furthermore, any modifications, alterations, and variations made to the above embodiments based on the essential technology of this application still fall within the scope of the technical solution of this application.

Claims

1. A current testing device, characterized by, The power output unit is configured to output a test current. The control unit is electrically connected to the power output unit and configured to control an output parameter of the test current. The power output unit comprises a first power regulating unit and a second power regulating unit connected to the first power regulating unit. The first power regulating unit comprises at least two groups of transformers connected in parallel, and is configured to switch different numbers of groups of transformers into an output circuit in response to a first instruction of the control unit, so as to regulate the test current output to different preset current intervals. The second power regulating unit comprises a variable transformer with adjustable primary coil turns, and is configured to adjust the primary coil turns of the variable transformer in response to a second instruction of the control unit, so as to adjust the test current in the preset current interval to a target value. Further comprising:

2. The current test device of claim 1, wherein, A control power transformer connected to an external AC power supply and configured to step down an external AC voltage to a preset voltage; A switching power supply module connected to an output end of the control power transformer and configured to receive the preset voltage and convert the preset voltage into at least two DC regulated output voltages, which are used to power the first power regulating unit and the second power regulating unit respectively. The first power regulating unit further comprises:

3. The current testing device of claim 1, wherein, At least two groups of contactors, each corresponding to a group of transformers; the secondary windings of the at least two groups of transformers are connected in parallel, and the main contact of each group of contactors is connected in series to the output circuit of the corresponding group of transformers, and the group of contactors is used to regulate the access state of the corresponding group of transformers and the circuit of the test current; A group of relays connected to the group of contactors, and configured to drive the group of contactors to act; The control unit is connected to the at least two groups of relays, and is configured to regulate the on-off state of the group of contactors through the group of relays, so as to form different numbers of parallel circuits with the at least two groups of transformers, and the parallel circuits correspond to the preset current intervals one by one. The variable transformer is provided with a brush on the adjustment shaft, and the second power regulating unit further comprises a drive motor connected to the control unit, which is configured to be driven by the control unit to rotate the adjustment shaft to drive the brush to slide on the winding surface of the primary coil, and the sliding brush adjusts the effective turns of the primary coil connected to the output circuit.

4. The current testing device of claim 3, wherein, The control unit is configured to:

5. The current testing device of claim 4, wherein, Determine a target value and a current value of the test current; Generate the second instruction to regulate the rotation direction and rotation angle of the drive motor according to the difference between the target value and the current value, and the test current is adjusted from the current value to the target value after the drive motor acts. ​ 6. The current testing device of claim 3, wherein, The contactor interlocking circuit is connected with each of the at least two contactor groups, and is configured to make the contactors in the current parallel circuit and the contactors in the remaining parallel circuits have different magnetization states when the first power regulating unit performs the step switching operation.

7. The current testing device of claim 3, wherein, The transformer group has four groups arranged in parallel, and the contactor groups are arranged corresponding to the transformer groups.

8. The current testing device of claim 2, wherein, The box and the control box arranged on the box are further included, the first power regulating unit, the second power regulating unit, the control power transformer and the switching power module are arranged in the box, and the control unit is arranged in the control box.

9. A test method characterized by, The test method is suitable for the current test device in any one of claims 1 to 8, and the test method comprises: receiving an external test current; generating a first instruction to control the number of transformer groups connected to the output circuit to coarsely adjust the test current to a preset current range; generating a second instruction to adjust the primary coil turns of the variable transformer to finely adjust the test current in the preset current range to a target value; outputting the test current with the target value to an external device under test.

10. The test method of claim 9, wherein, Further comprising: detecting the output state of the test current and the test state of the device under test in a preset sampling period; in response to any abnormality in the output state and the test state, recording the abnormal value of the test current at the abnormality and stopping outputting the test current.

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