Method and device for equal-turn test of parallel coils of power transformer

Abstract

The invention discloses a power transformer parallel coil equal-turn test method and device, and belongs to the technical field of power transformers, and the device comprises a power voltage regulator, a switch, a voltmeter, an ammeter, and a to-be-tested power transformer. The to-be-tested power transformer comprises a primary winding, a secondary winding and an iron core, the secondary winding comprises a plurality of windings which are connected in parallel, coils of the windings are axially arranged, and the primary winding and the secondary winding are arranged on the two sides of the iron core; the primary winding, the power voltage regulator, the switch and the voltmeter form an excitation loop for exciting the power transformer to be tested; the secondary winding and the ampere meter form a feedback loop for measuring the current of the feedback loop; one end of the iron core is grounded; the test method comprises the following steps: closing a switch of an excitation loop, adjusting a power supply voltage regulator, carrying out voltage measurement through a voltmeter, and exciting an iron core by a primary winding; the current in the feedback loop is detected through the ampere meter, and the coil states of the windings of the secondary winding are judged according to the current.

Description

Technical Field

[0001] The invention belongs to the technical field of power transformers, and in particular relates to a method and a device for equal-turns testing of parallel coils of a power transformer. Background Art

[0002] Power transformers are crucial components of power transmission and distribution systems, transforming voltage to meet the demands of diverse power applications. In some specially designed power transformers, two parallel coils are placed on the same core leg, arranged axially with equal turns and opposite winding directions. This design offers unique advantages. For example, in specific electromagnetic coupling and current distribution scenarios, it can effectively balance magnetic field distribution, reduce magnetic leakage, improve transformer operating efficiency and stability, reduce energy loss, and help optimize the transformer's overall performance and reliability.

[0003] However, in actual transformer manufacturing, due to the typically large number of coil turns and complex winding processes, it's impossible to verify visually that the two parallel coils have met the requirements of equal turns and opposite winding directions. Inconsistent turns lead to varying inductances in the coils, which in turn can cause uneven current distribution during transformer operation. Some coils may overheat due to excessive current, accelerating the aging of insulation materials, reducing the transformer's lifespan, and even causing failure. If the opposite winding direction error goes undetected, it can disrupt the transformer's internal magnetic field distribution, affecting the transformer's proper electromagnetic conversion function, leading to unstable output voltage and reduced efficiency. In severe cases, it can damage the entire power equipment, impacting the safe and stable operation of the power system.

[0004] Currently, the industry lacks an effective, convenient, and accurate detection method that can quickly and reliably verify whether the two parallel coils have equal turns and opposite winding directions after the transformer is wound. Therefore, developing a detection technology to address this problem is of great practical significance. It can fill this technical gap and ensure the manufacturing quality of power transformers and the stable operation of power systems. Summary of the Invention

[0005] The purpose of the present invention is to overcome the problem that it is impossible to verify from appearance whether two parallel coils have equal number of turns and opposite winding directions, and propose a method and device for equal turns test of parallel coils of power transformers.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: In a first aspect, the present invention provides a device for equal-turns testing of parallel coils of a power transformer, comprising a power voltage regulator, a switch, a voltmeter, an ammeter, and a power transformer to be tested; The power transformer to be tested includes a primary winding, a secondary winding and an iron core. The secondary winding includes a plurality of windings connected in parallel, the coils of the plurality of windings are arranged axially, and the primary winding and the secondary winding are arranged on both sides of the iron core. The primary winding, power supply voltage regulator, switch, and voltmeter form an excitation circuit for exciting the power transformer to be tested; the secondary winding and ammeter form a feedback circuit for measuring the current in the feedback circuit; one end of the iron core is grounded.

[0007] Furthermore, one end of the primary winding is connected to one end of the switch, the other end of the switch is connected to one end of the power regulator and one end of the voltmeter, and the other end of the primary winding is connected to the other end of the power regulator and the other end of the voltmeter.

[0008] Furthermore, one end of the primary winding and the connection ends of several windings of the secondary winding are terminals of the same name.

[0009] Furthermore, one end of the secondary winding is connected to one end of the ammeter, and the other end of the secondary winding is connected to the other end of the ammeter.

[0010] Furthermore, the secondary winding includes a secondary winding I and a secondary winding II connected in parallel, and the coils of the secondary winding I and the coils of the secondary winding II are arranged axially.

[0011] Furthermore, one end of the secondary winding I is connected to one end of the secondary winding II, the other end of the secondary winding I is connected to one end of the ammeter, and the other end of the secondary winding II is connected to the other end of the ammeter.

[0012] Furthermore, the power voltage regulator adopts an adjustable power supply with a voltage adjustment range of 0-220V.

[0013] Furthermore, the switch is an emergency stop switch, the voltmeter is a digital AC voltmeter, and the ammeter is a milliampere-level ammeter.

[0014] In a second aspect, the present invention provides a method for performing an equal-turns test on parallel coils of a power transformer, using an apparatus for performing an equal-turns test on parallel coils of a power transformer, comprising the following steps: Close the switch of the excitation circuit, adjust the power supply voltage regulator, measure the voltage through the voltmeter, and excite the core through the primary winding; The current in the feedback loop is detected by an ammeter, and the coil states of several windings of the secondary winding are determined according to the current magnitude.

[0015] Furthermore, the secondary winding includes a secondary winding I and a secondary winding II connected in parallel, and the coils of the secondary winding I and the coils of the secondary winding II are arranged axially; When the current in the feedback loop is zero, it is determined that the coils of secondary winding I and secondary winding II have the same number of turns and opposite winding directions; When the current in the feedback loop is not at the zero milliampere level, it is determined that the number of turns of the coil of the secondary winding I is not equal to that of the coil of the secondary winding II.

[0016] Compared with the prior art, the present invention has the following beneficial technical effects: The present invention proposes a device for testing the equal turns of parallel coils of a power transformer. The excitation circuit includes the primary winding of the transformer to be tested, which is used to excite the transformer to be tested; the feedback circuit includes the secondary winding of the transformer to be tested, which is used to measure the current in the feedback circuit. When the number of turns of the transformer coil is relatively large, it is impossible to verify from the appearance whether the two parallel coils have the same number of turns and are wound in opposite directions after winding. By building a test device provided by the present invention, an electrical method is used to intuitively determine whether the two parallel axially arranged coils on the same iron core column of a power transformer have the same number of turns and are wound in opposite directions, thereby greatly improving the accuracy of the judgment and also improving production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The drawings described herein are for illustrative purposes only and are not intended to limit the scope of the present invention in any way. In addition, the shapes and proportional dimensions of the components in the drawings are only schematic and are used to help understand the present invention, and are not intended to specifically limit the shapes and proportional dimensions of the components of the present invention. In the drawings: Figure 1 The figure is a schematic diagram of a device for equal turns test of parallel coils of power transformers.

[0018] Among them, 1 is the power regulator, 2 is the switch, 3 is the voltmeter, 4 is the primary winding, 5 is the secondary winding I, 6 is the secondary winding II, 7 is the iron core, 8 is the ammeter, and 9 is the power transformer to be tested. DETAILED DESCRIPTION

[0019] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0020] It should be noted that when an element is referred to as being "disposed on" another element, it may be directly on the other element or there may be an element centered thereon. When an element is referred to as being "connected to" another element, it may be directly connected to the other element or there may be an element centered thereon. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only embodiments.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one skilled in the art to which this invention pertains. The terms used in this specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0022] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0023] Example 1 This embodiment provides a device for conducting an equal-turns test on parallel coils of a power transformer, comprising a power supply voltage regulator 1, a switch 2, a voltmeter 3, an ammeter 8, and a power transformer 9 to be tested. The power transformer 9 to be tested comprises a primary winding 4, a secondary winding, and an iron core 7. The secondary winding comprises several windings connected in parallel, the coils of the several windings being arranged axially, and the primary winding 4 and the secondary winding being arranged on either side of the iron core 7. The primary winding 4, the power supply voltage regulator 1, the switch 2, and the voltmeter 3 form an excitation circuit for exciting the power transformer 9 to be tested. The secondary winding and the ammeter 8 form a feedback circuit for measuring the current in the feedback circuit. One end of the iron core 7 is grounded. In a power transformer, the secondary winding comprises several windings connected in parallel, with the coils arranged axially. When conducting an equal-turns test using the device provided in this embodiment, the excitation circuit is used to excite the power transformer to be tested, generating magnetic flux in the iron core, thereby inducing an electromotive force in the secondary winding. Since the number of turns of each parallel winding should be the same, the electromotive force induced by each winding should theoretically be the same under the same magnetic flux change. The feedback loop uses an ammeter to measure the current. If the parallel windings have the same number of turns, the current distribution will be as expected. However, any discrepancies in the number of turns will result in different induced electromotive forces in the windings, leading to abnormal current distribution. This device accurately detects the consistency of the turns in the parallel coils, promptly identifying any discrepancies and preventing transformer operational failures such as local overheating and increased losses, thereby ensuring safe and stable operation of the transformer. The device's circuit structure is simple and straightforward, with clear divisions between the excitation and feedback circuits, making operation and connection easy for testers. Testers simply connect all components according to the specified wiring method to begin testing, reducing operational complexity and error rates. A voltmeter and ammeter measure the voltage in the excitation circuit and the current in the feedback circuit, respectively. These measurements provide a visual representation of the transformer's operating status and test results. By reading the voltmeter and ammeter readings, testers can quickly determine the number of turns in the transformer's parallel coils, improving test efficiency. It is suitable for parallel coil equal-turn tests of power transformers of different specifications and capacities. As long as the primary and secondary winding structures of the power transformer to be tested meet the test requirements, the device can be used for testing. It has strong versatility and adaptability.

[0024] One end of primary winding 4 is connected to one end of switch 2. The other end of switch 2 is connected to one end of power supply voltage regulator 1 and one end of voltmeter 3. The other end of primary winding 4 is connected to the other end of power supply voltage regulator 1 and the other end of voltmeter 3. One end of primary winding 4 and the connection ends of several secondary windings are the same. One end of the secondary winding is connected to one end of ammeter 8, and the other end of the secondary winding is connected to the other end of ammeter 8. The secondary winding includes secondary winding I5 and secondary winding II6 connected in parallel, with the coils of secondary winding I5 and secondary winding II6 arranged axially. One end of secondary winding I5 is connected to one end of secondary winding II6, the other end of secondary winding I5 is connected to one end of ammeter 8, and the other end of secondary winding II6 is connected to the other end of ammeter 8.

[0025] Several of the primary and secondary windings have identical terminals. During the excitation process, according to the law of electromagnetic induction, the induced electromotive force (EMF) at these terminals is directed in the same direction when the magnetic flux changes. When the power supply voltage regulator supplies voltage to excite the primary winding, secondary windings I and II generate induced EMFs in the same direction due to this identical terminal relationship. If the two windings have the same number of turns, when connected in parallel and forming a feedback loop with an ammeter, the current distribution will conform to theoretical expectations. However, if the number of turns is unequal, the difference in induced EMF will result in an abnormal current distribution. The ammeter can visually detect this difference, accurately determining the consistency of the turns in the parallel coils and promptly identifying potential problems such as incorrect turns. Measuring the current in the feedback loop not only determines the number of turns but also indirectly indicates coil parameters such as resistance and inductance. Problems such as inter-turn shorts or insulation damage can cause resistance changes, which in turn affect the current flow. Abnormal ammeter readings can indicate these potential faults, enabling a comprehensive assessment of the performance of the parallel coils. The excitation circuit can be precisely regulated by the power supply voltage regulator to control the excitation current. The voltmeter monitors the excitation circuit voltage in real time. Testers can adjust the voltage regulator output appropriately based on the voltage value and transformer rated parameters to avoid excessive excitation current that could damage the transformer core and winding insulation, ensuring a safe test process. Grounding the core eliminates floating potentials and prevents potential differences between different parts of the core caused by electromagnetic fields, which can lead to partial discharge. This prevents damage to the core insulation caused by long-term operation and ensures transformer reliability. The voltmeter and ammeter measure the excitation circuit voltage and feedback circuit current, respectively. The measured data provide a direct reflection of the transformer's operating status and test results. Testers can quickly read the values and determine the number of turns in parallel coils, eliminating the need for complex data processing and analysis, facilitating timely decision-making. The wiring method is suitable for testing equal-turn parallel coils on power transformers of varying specifications and capacities. As long as the transformer's primary and secondary winding structures meet the test requirements—that is, the primary and secondary windings have identical terminals and the secondary windings can be connected in parallel—the device can be used for testing, demonstrating its versatility and adaptability.

[0026] Power supply voltage regulator 1 uses an adjustable power supply with a voltage adjustment range of 0-220V. Switch 2 is an emergency stop switch, voltmeter 3 is a digital AC voltmeter, and ammeter 8 is a milliampere-level ammeter. The adjustable power supply voltage regulator allows precise voltage adjustment, allowing testers to gradually adjust the voltage according to specific test requirements and transformer parameters to observe the transformer's response at different voltages. Starting the voltage adjustment from 0V ensures the transformer is in a safe state at the start of the test, preventing damage to the transformer and test equipment caused by sudden high voltage application. Furthermore, if an abnormality is detected during the test, the voltage can be promptly reduced to minimize the risk of an accident. The emergency stop switch instantly cuts off power and quickly stops the test, preventing further escalation of the accident and protecting testers and equipment. Compared to conventional switches, the emergency stop switch requires no complex operation steps, significantly improving the efficiency of emergency response. The digital AC voltmeter utilizes advanced electronic technology and digital processing algorithms to provide highly accurate voltage measurement results. In equal-turn tests on parallel coils of power transformers, the current in the feedback loop is relatively low, and the milliampere-level ammeter has high sensitivity, enabling accurate measurement of even small current changes. The milliampere ammeter has a smaller range and finer scale, so the tester can observe the tiny fluctuations of the current more clearly, which helps to conduct in-depth analysis of the test results.

[0027] This embodiment further provides a method for equal-turns testing of parallel coils of a power transformer, using a device for equal-turns testing of parallel coils of a power transformer, comprising the following steps: Close the switch 2 of the excitation circuit, adjust the power supply voltage regulator 1, measure the voltage through the voltmeter 3, and the primary winding 4 excites the iron core 7; use the ammeter 8 to detect the current in the feedback circuit, and judge the coil status of several windings of the secondary winding based on the current.

[0028] The secondary winding includes a secondary winding I5 and a secondary winding II6 connected in parallel, and the coil of the secondary winding I5 and the coil of the secondary winding II6 are arranged axially; when the current in the feedback loop is zero, it is judged that the number of turns of the coil of the secondary winding I5 and the coil of the secondary winding II6 are equal and the winding directions are opposite; when the current in the feedback loop is not at the zero milliampere level, it is judged that the number of turns of the coil of the secondary winding I5 and the coil of the secondary winding II6 are not equal.

[0029] The test method only requires a few simple steps, such as closing the excitation circuit switch, adjusting the power supply voltage regulator, measuring the voltage, and detecting the current in the feedback circuit. Testers can complete the test by following the steps without complex operating skills and professional knowledge, which reduces the difficulty and threshold of the test. Measurements are made using a digital AC voltmeter and milliampere ammeter, and the readings are intuitive and clear. Testers can read the voltage and current values directly from the instrument without the need for complex calculations and conversions, which improves test efficiency and data accuracy. The emergency stop switch equipped in the device can quickly cut off the power supply and stop the test in the event of an abnormality during the test, preventing further escalation of the accident. Through accurate equal-turn tests, problems with the transformer's parallel coils can be discovered in a timely manner, and repairs or adjustments can be made before the transformer is put into operation, avoiding transformer operation failures caused by problems such as inconsistent turns, and reducing maintenance costs and downtime losses.

[0030] Example 2 This test is designed to use a specific device for equal-turns test of parallel coils of power transformers to accurately determine whether the number of turns of the secondary parallel coils of power transformers, such as secondary winding I and secondary winding II, is equal, providing a reliable basis for quality inspection, performance evaluation and subsequent safe and stable operation of power transformers.

[0031] A device for testing parallel coils of a power transformer with equal turns comprises a power voltage regulator 1, a switch 2, a voltmeter 3, an ammeter 8, and a power transformer to be tested 9. The power transformer to be tested 9 comprises a primary winding 4, a secondary winding I 5 connected in parallel with a secondary winding II 6, and an iron core 7. The primary winding 4 and the secondary winding are arranged on both sides of the iron core 7, and one end of the iron core 7 is grounded.

[0032] Before testing, carefully inspect the exterior of all components of the test equipment to ensure they are free of damage, deformation, or looseness. Specifically, check the adjustment knob of the power supply voltage regulator 1 for flexibility, the smooth opening and closing of switch 2, and the normal operation of the pointers or displays of the voltmeter 3 and ammeter 8. Check the insulation condition of the power transformer 9 under test. Use an insulation resistance tester to measure the insulation resistance between the windings and the core 7, and between the windings themselves, to ensure that the insulation resistance meets the relevant standards. Reconfirm that the excitation and feedback circuits are correctly wired according to the device connection requirements. Check the connections between the primary winding 4 and the switch 2, power supply voltage regulator 1, and voltmeter 3, as well as the connections between secondary windings I 5 and II 6 and ammeter 8, paying particular attention to the correct connection of the same-name terminals. Ensure the test environment is dry and well-ventilated, with temperature and humidity within the appropriate range. Generally, the temperature should be between 5°C and 40°C, and the relative humidity should not exceed 80%. Avoid testing in humid, high-temperature environments, or in the presence of corrosive gases, as this may affect test results and equipment safety.

[0033] Adjust the output voltage of power supply regulator 1 to 0V to ensure that no excessive inrush current is generated when closing switch 2. Verify that switch 2 is open in preparation for subsequent closing. Zero voltmeter 3 and ammeter 8 to ensure the accuracy of their initial settings before measurement. If the meter is digital, check that the display is 0. If it is a pointer meter, gently rotate the meter until the pointer points to 0.

[0034] Close switch 2 slowly and smoothly to avoid arcing or surge currents caused by rapid closing. Slowly adjust the power supply voltage regulator 1 to gradually increase the output voltage. During the adjustment process, closely observe the changes in the reading on voltmeter 3 and the reading on ammeter 8. The voltage adjustment speed should not be too fast, generally no more than 5V per second, to accurately observe the current changes. Use voltmeter 3 to measure the voltage across the primary winding 4 in real time to ensure that the voltage is within the set test voltage range. Multiple voltage measurement points can be set, such as 50V, 100V, 150V, and 200V. After each voltage measurement point stabilizes for a period of time, such as 1-2 minutes, record the voltage value. Use ammeter 8 to monitor the current in the feedback loop. At each voltage measurement point, wait for the current to stabilize and then record the current value. Record 3-5 current readings for each voltage measurement point and take the average value as the current value at that voltage to reduce measurement error.

[0035] When the current in the feedback loop remains consistently at zero milliamperes, it can be preliminarily determined that the coils in secondary windings I5 and II6 have the same number of turns but are wound in opposite directions. At this point, the induced electromotive forces generated by the two secondary windings cancel each other out, resulting in no current flowing in the feedback loop. To further confirm this, repeat the test at different voltages to see if the current remains zero. If the current remains zero across multiple tests, it can be confirmed that the secondary windings have the same number of turns but are wound in opposite directions.

[0036] When the current in the feedback loop is not in the zero milliampere range, it is determined that the number of turns in secondary windings I5 and II6 is unequal. The magnitude of the current is related to the degree of the difference in turns; a greater difference in turns may indicate a higher current value. Record the current values at different voltages and plot a current-voltage characteristic curve. By analyzing the slope and trend of the curve, we can further understand the general extent of the difference in turns. For example, a steeper slope indicates a significant difference in turns.

[0037] After completing data recording and analysis, slowly adjust the power supply voltage regulator 1 to reduce the output voltage to 0V. During this step-down process, carefully monitor the readings of voltmeter 3 and ammeter 8 to ensure a steady voltage drop. After confirming that the voltage has dropped to 0V, disconnect switch 2 to cut off the power supply. Arrange the test equipment and clean the test site. Return the power supply voltage regulator 1, switch 2, voltmeter 3, ammeter 8, and other equipment to their original locations, and properly store the power transformer 9 under test.

[0038] During the test, operators must strictly adhere to safety operating procedures and wear necessary protective equipment, such as insulating gloves and shoes. Avoid direct contact with live parts to prevent electric shock. When adjusting the power supply voltage regulator 1, carefully observe the reading of the ammeter 8 to prevent excessive current from damaging the ammeter 8 or the power transformer under test 9. If an abnormal increase in current is detected, immediately disconnect the power supply and investigate the cause of the fault. Avoid allowing the output voltage of the power supply voltage regulator 1 to exceed its rated voltage range to avoid damage to the equipment.

[0039] To ensure the accuracy of test data, ensure that voltmeter 3 and ammeter 8 are calibrated and within their validity period. Also, be careful and thorough when recording data to avoid human error. Minimize external interference during the test, such as avoiding strong electromagnetic fields to prevent impacting the instrument's measurement accuracy. If any abnormalities occur during the test, such as smoke, odor, or unusual noises, immediately disconnect the power supply, stop the test, and investigate the cause of the malfunction. Retry the test only after correcting the problem.

[0040] Example 3 See also Figure 1 , a device for equal turns test of parallel coils of power transformers, comprising: The power supply voltage regulator 1, switch 2, voltmeter 3, primary winding 4, secondary winding I5, secondary winding II6, iron core 7, and power transformer 9 to be tested are composed of: ab represents the two ends of the coil of the primary winding 4, AB represents the two ends of the coil of the secondary winding I5, A'B' represents the two ends of the coil of the secondary winding II6, and the coils of the secondary winding I5 and the secondary winding II6 are connected in parallel to form the secondary winding of the power transformer 9 to be tested; the secondary winding has two coils AB and A'B' arranged axially; one end a of the primary winding 4 and one end A of the secondary winding I5 and one end A' of the secondary winding II6 are the same-named terminals according to the principle of electromagnetic induction. Figure 1 middle Indicates terminals with the same name. Primary winding 4, power supply regulator 1, voltmeter 3, and switch 2 form an excitation circuit. Terminal A of secondary winding I5 is connected to terminal A' of secondary winding II6. Terminal B of secondary winding I5, ammeter 8, and terminal B' of secondary winding II6 form a feedback circuit.

[0041] Power supply regulator 1 is an adjustable power supply with a voltage adjustment range of 0-220V. Voltmeter 3 is a digital AC voltmeter that provides a visual reading of the output voltage of power supply regulator 1. Switch 2 is an emergency stop switch that quickly shuts off the circuit power in the event of an abnormality. The same-named terminals of secondary windings I5 and II6 are connected separately. Ammeter 8 is a milliampere-level ammeter capable of measuring small current changes. The windings A' and B' of secondary windings I5 and II6 are wound in opposite directions, generating a reverse electromotive force through the principle of electromagnetic induction.

[0042] A method for testing equal turns of parallel coils of a power transformer, using a device for testing equal turns of parallel coils of a power transformer, wherein when the number of turns of the coil of the secondary winding I5 is the same as that of the coil of the secondary winding II6, the induced back electromotive force is completely canceled, and the current in the feedback loop is zero. The details are as follows: like Figure 1 As shown, the present invention provides an equal-turns test device for parallel coils of a power transformer, comprising a power transformer 9 to be tested, comprising a primary winding 4, a secondary winding I5, and a secondary winding II6. The primary winding 4, a power supply voltage regulator 1, a voltmeter 3, and a switch 2 form an excitation circuit. The secondary winding comprises two parallel coils of equal turns, wound in opposite directions, with turns of the secondary winding I5 and the secondary winding II6 arranged axially. One end a of the primary winding 4, one end A of the secondary winding I5, and one end A' of the secondary winding II6 are the same terminals according to the principle of electromagnetic induction. One end A of the secondary winding I5 and one end A' of the secondary winding II6 are connected, and the other end B of the secondary winding I5, an ammeter 8, and the other end B' of the secondary winding II6 are connected to form a feedback loop.

[0043] When switch 2 is closed in the excitation circuit, power regulator 1 is adjusted, and voltmeter 3 measures the voltage, primary winding 4 excites transformer core 7. Because secondary windings I5 and II6 are wound in opposite directions, a counter-electromotive force is induced through the principle of electromagnetic induction. When secondary windings I5 and II6 have the same number of turns, the induced counter-electromotive force completely cancels out, and the current in the feedback loop is zero.

[0044] Through the above principle analysis, we can conclude that: When the excitation circuit gives the iron core appropriate excitation, the current in the feedback circuit is zero, and it can be determined that the two parallel coils of the secondary winding have equal number of turns and opposite winding directions.

[0045] When the excitation circuit gives the iron core appropriate excitation, the current in the feedback circuit is not at the zero milliampere level, which indicates that the number of turns of the two parallel coils of the secondary winding are not equal.

[0046] Many embodiments and applications beyond the examples provided will be apparent to those skilled in the art upon reading the foregoing description. Therefore, the scope of the present teachings should be determined not with reference to the foregoing description, but rather with reference to the preceding claims, along with the full scope of equivalents to which such claims are entitled. For the purpose of completeness, all articles and references, including the disclosures of patent applications and publications, are incorporated herein by reference. The omission of any aspect of the subject matter disclosed herein from the preceding claims is not a disclaimer of such subject matter, nor should it be interpreted that the applicants did not consider such subject matter to be part of the disclosed inventive subject matter.

[0047] The above content is a further detailed description of the present invention, and it cannot be considered that the specific implementation methods of the present invention are limited to these. For ordinary technicians in the technical field to which the present invention belongs, they can make several simple deductions or substitutions without departing from the concept of the present invention, which should be regarded as belonging to the determined protection scope of the present invention submitted.

Claims

1. A device for equal turns test of parallel coils of power transformers, characterized in that: It includes a power supply voltage regulator (1), a switch (2), a voltmeter (3), an ammeter (8), and a power transformer to be tested (9); The power transformer (9) to be tested comprises a primary winding (4), a secondary winding and an iron core (7), wherein the secondary winding comprises a plurality of windings connected in parallel, the coils of the plurality of windings are arranged axially, and the primary winding (4) and the secondary winding are arranged on both sides of the iron core (7); The primary winding (4), the power supply voltage regulator (1), the switch (2), and the voltmeter (3) form an excitation circuit for exciting the power transformer (9) to be tested; the secondary winding and the ammeter (8) form a feedback circuit for measuring the current in the feedback circuit; and one end of the iron core (7) is grounded.

2. The device for equal turns test of parallel coils of a power transformer according to claim 1, characterized in that: One end of the primary winding (4) is connected to one end of the switch (2), the other end of the switch (2) is connected to one end of the power supply voltage regulator (1) and one end of the voltmeter (3), and the other end of the primary winding (4) is connected to the other end of the power supply voltage regulator (1) and the other end of the voltmeter (3).

3. The device for equal turns test of parallel coils of a power transformer according to claim 2, characterized in that: One end of the primary winding (4) and the connection ends of several windings of the secondary winding are the same-named ends.

4. The device for equal turns test of parallel coils of a power transformer according to claim 1, characterized in that: One end of the secondary winding is connected to one end of the ammeter (8), and the other end of the secondary winding is connected to the other end of the ammeter (8).

5. The device for equal turns test of parallel coils of a power transformer according to claim 1, characterized in that: The secondary winding comprises a secondary winding I (5) and a secondary winding II (6) connected in parallel, and the coils of the secondary winding I (5) and the coils of the secondary winding II (6) are arranged axially.

6. The device for equal turns test of parallel coils of a power transformer according to claim 5, characterized in that: One end of the secondary winding I (5) is connected to one end of the secondary winding II (6), the other end of the secondary winding I (5) is connected to one end of the ammeter (8), and the other end of the secondary winding II (6) is connected to the other end of the ammeter (8).

7. The device for equal turns test of parallel coils of a power transformer according to claim 1, characterized in that: The power supply voltage regulator (1) adopts an adjustable power supply with a voltage adjustment range of 0-220V.

8. The device for equal turns test of parallel coils of a power transformer according to claim 1, characterized in that: The switch (2) is an emergency stop switch, the voltmeter (3) is a digital AC voltmeter, and the ammeter (8) is a milliampere-level ammeter.

9. A method for equal turns test of parallel coils of power transformers, characterized in that: The device for equal turns test of parallel coils of a power transformer according to any one of claims 1 to 8 comprises the following steps: The switch (2) of the excitation circuit is closed, the power supply voltage regulator (1) is adjusted, the voltage is measured by the voltmeter (3), and the primary winding (4) excites the core (7); The current in the feedback loop is detected by an ammeter (8), and the coil states of the plurality of windings of the secondary winding are determined according to the current.

10. The method for equal turns test of parallel coils of a power transformer according to claim 9, characterized in that: The secondary winding comprises a secondary winding I (5) and a secondary winding II (6) connected in parallel, wherein the coil of the secondary winding I (5) and the coil of the secondary winding II (6) are arranged axially; When the current in the feedback loop is zero, it is determined that the coils of the secondary winding I (5) and the coils of the secondary winding II (6) have the same number of turns and are wound in opposite directions; When the current in the feedback loop is not at the zero milliampere level, it is determined that the number of turns of the coil of the secondary winding I (5) is not equal to the number of turns of the coil of the secondary winding II (6).

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