A device for detecting a broken skin point of a variable frequency motor winding

Abstract

The utility model provides a kind of for the detection device of frequency conversion motor winding broken skin point, including insulation withstand voltage tester;High pressure probe is connected with the output end of the insulation withstand voltage tester, for being contacted with the winding of measured motor;Reference motor, the core ground of the reference motor is connected with the ground end of the insulation withstand voltage tester after, the winding output end of the reference motor is connected with the winding output end of the measured motor;Wherein, the core of the measured motor is in the state of suspension.The utility model provides a kind of for the detection device of frequency conversion motor winding broken skin point, high sensitivity positioning to broken skin point can be realized, while the current energy flowing through broken skin point is limited in safety range, avoid to produce electric arc ablation or hit black to insulating material, improve the security and reliability of detection.

Description

Technical Field

[0001] This utility model belongs to the field of motor testing technology, specifically relating to a device for detecting the breakage point of the winding of a variable frequency motor. Background Technology

[0002] In motor manufacturing and repair, the insulation integrity between the winding copper wires and the iron core is crucial. Traditional industry methods for testing insulation defects commonly use high-voltage probes, typically applying high voltage directly to the winding-core ground or low voltage to the winding-to-ground, and measuring the leakage current to determine overall insulation quality. However, both methods have significant shortcomings: First, there is destructive damage: when the high-voltage probe passes through the damaged area, the high voltage will discharge to the stator core through the damaged area. Due to the low circuit impedance and high discharge energy, an electric arc is easily generated at the fault point, burning the copper wire and blackening and carbonizing the surrounding insulating groove paper. This kind of restorative testing actually causes secondary damage, increasing maintenance costs and time.

[0003] Secondly, there is capacitive current interference: distributed capacitance exists between the stator winding and the core, which generates capacitive leakage current. When testing AC high voltage, this current can mask the resistive fault current generated by tiny punctures, reducing detection sensitivity.

[0004] Third, there is a conflict between sensitivity and safety: to improve positioning sensitivity, a higher test voltage is required, but high voltage will exacerbate the aforementioned destructiveness. If the voltage is reduced to minimize damage, tiny abrasions may not generate a sufficiently large leakage current and thus be missed.

[0005] Therefore, the industry urgently needs a testing solution that can sensitively detect at high test voltages without causing secondary damage to the insulation. Summary of the Invention

[0006] To address the shortcomings of the existing technology, this utility model provides a detection device for the insulation breakage point of a variable frequency motor winding. This device can achieve highly sensitive positioning of the breakage point while limiting the current energy flowing through the breakage point to a safe range, avoiding arc erosion or blackening of the insulation material, and improving the safety and reliability of the detection.

[0007] The technical effects to be achieved by this utility model are realized through the following technical aspects: This utility model provides a device for detecting the breakage point of the winding of a variable frequency motor, comprising: Insulation withstand voltage tester; A high-voltage probe is connected to the output end of the insulation withstand voltage tester and is used to contact the windings of the motor under test. A reference motor, the iron core of which is grounded and connected to the ground terminal of the insulation withstand voltage tester, and the winding output terminal of the reference motor is connected to the winding output terminal of the motor under test. The iron core of the motor under test is suspended in the air.

[0008] In some implementations, conductive units are also included; The conductive unit includes a conductive support assembly and a grounding terminal disposed on the conductive support assembly; The iron core of the reference motor is in contact with the conductive support assembly, and the grounding terminal is connected to the ground terminal of the insulation withstand voltage tester through a ground wire. The conductive unit ensures the reliable grounding of the iron core of the reference motor.

[0009] In some implementations, the conductive support assembly includes a conductive support panel and a conductive support frame disposed on the conductive support panel; The grounding terminal is disposed on the conductive support panel, and the reference motor is disposed on the conductive support frame. The conductive support panel facilitates the overall position movement and setting of the conductive support assembly, while the conductive support frame provides stable support for the reference motor, ensuring the reliable grounding of the reference motor's core.

[0010] In some implementations, the conductive support frame includes a metal rod and a metal base; One end of the metal rod is connected to the conductive support panel, and the other end of the metal rod is connected to the metal base; The metal seat is a V-shaped structure with its opening facing away from the metal rod. The V-shaped metal seat can provide good positional stability for the reference motor and ensure stable contact with the iron core of the reference motor.

[0011] In some implementations, the metal base includes a first contact portion and a second contact portion; The included angle between the first contact portion and the second contact portion is 120°-130°. This included angle range can ensure both good positional stability for the reference motor and stable contact with the iron core of the reference motor.

[0012] Some implementations also include an insulated frame; The insulation withstand voltage tester, the conductive unit, and the motor under test are all mounted on the insulating frame. The insulating bracket supports and fixes other components, facilitating the overall use of the testing device.

[0013] Some implementations also include electrical connectors; The winding output terminal of the reference motor and the winding output terminal of the motor under test are connected by the electrical connector. The electrical connector facilitates the connection between the winding output terminals of the reference motor and the motor under test, and ensures the stability of the connection.

[0014] In some implementations, the insulation withstand voltage tester has a current measurement alarm unit; The current measurement alarm unit is used to monitor the leakage current in the circuit. When the leakage current in the circuit exceeds the set threshold of the current measurement alarm unit, the current measurement alarm unit issues an alarm signal to limit the current energy in the circuit within a safe range and avoid damage to the motor under test.

[0015] In some implementations, the current measurement alarm unit has a set threshold of 0.3mA; The high-voltage probe has a test voltage of AC3000V, enabling highly sensitive location of the skin puncture point under high voltage.

[0016] In some implementations, the leakage current of the reference motor is 1.5-1.7 mA, which improves the accuracy of detecting abrasion points.

[0017] In summary, this utility model has at least the following advantages: This utility model provides a detection device for the insulation breakage point of a variable frequency motor winding. By introducing a special current limiting and signal modulation unit, namely a reference motor, into the test circuit, and ensuring that the iron core of the motor under test is not directly grounded, there will be no damage to the copper wire. Because the iron core of the reference motor is grounded, the discharge between the high-voltage probe and the iron core of the motor under test will not form a large current loop, and the slot paper will not be blackened. This achieves high-sensitivity positioning of the insulation breakage point under high voltage, and limits the current energy flowing through the insulation breakage point to a safe range, avoiding arc erosion or blackening of the insulation material, thus improving the safety and reliability of the detection. In addition, only a normal, intact reference motor is required as the reference unit, without the need for complex electronic circuits, resulting in low implementation cost and easy promotion in factories and repair workshops. Attached Figure Description

[0018] Figure 1 A schematic diagram of the detection device provided in Embodiment 1 of this utility model; Figure 2 A schematic diagram of a reference motor provided in Embodiment 1 of this utility model; Figure 3 A schematic diagram of the detection device provided in Embodiment 2 of this utility model; Marked in the image: 100. Insulation withstand voltage tester; 200. High-voltage probe; 300. The motor under test; 400, Reference motor; 410, Iron core; 420, Winding; 500, Conductive unit; 510, Conductive support assembly; 511, Conductive support panel; 512, Conductive support frame; 5121, Metal rod; 5122, Metal base; 5122a, First contact portion; 5122b, Second contact portion; 520, Grounding terminal; 600. Insulated frame; 700. Electrical connector. Detailed Implementation

[0019] To facilitate understanding of the present invention, a more comprehensive description will be given below in conjunction with the accompanying drawings and specific embodiments. The drawings illustrate preferred embodiments of the invention. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the invention.

[0020] It should be noted that when a component is said to be "fixed to" another component, it can be directly attached to the other component or there may be an intervening component. When a component is said to be "connected to" another component, it can be directly connected to the other component or there may be an intervening component.

[0021] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this invention is in use. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention. In addition, the terms "first," "second," "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0023] Example 1: Please see Figure 1 and Figure 2 A device for detecting the insulation failure point of a variable frequency motor winding includes an insulation withstand voltage tester 100, a high voltage probe 200, and a reference motor 400.

[0024] Here, the insulation withstand voltage tester 100 is used to apply a high voltage higher than the normal operating voltage for a certain period of time to detect whether the leakage current of the motor under test 300 is within the specified range, so as to determine whether the insulation is good.

[0025] The high-voltage probe 200 is connected to the output end of the insulation withstand voltage tester 100 and is used to contact the winding of the motor 300 under test. Typically, the high-voltage probe 200 has a metal tip, which is used to contact the winding of the motor 300 under test to detect the break point in the winding of the motor 300 under test.

[0026] The iron core 410 of the reference motor 400 is grounded and connected to the ground terminal of the insulation withstand voltage tester 100. The output terminal of the winding 420 of the reference motor 400 is connected to the output terminal of the winding of the motor under test 300. The iron core of the motor under test 300 is in a suspended state.

[0027] For the detection of motor winding breakage points, the traditional method is to form a direct leakage path from the iron core of the motor under test 300 to ground. In this embodiment, the direct leakage path is reconstructed into a series capacitive reactance path from the iron core of the motor under test 300 to the iron core of the reference motor 400 to ground.

[0028] Specifically, existing grounding methods involve grounding the iron core of the motor under test 300. This can lead to discharge between the high-voltage probe 200 and the iron core of the motor under test 300, causing blackening of the slot paper, or grounding of the winding. When the high-voltage test breaks the insulation, a direct circuit is formed, causing significant damage to the copper wire. In this embodiment, a reference motor 400 is connected in series between the insulation withstand voltage tester 100 and the motor under test 300. The iron core of the motor under test 300 is not directly grounded, thus avoiding damage to the copper wire. Because the iron core 410 of the reference motor 400 is grounded, the discharge between the high-voltage carbon probe and the iron core of the motor under test 300 does not form a large current circuit, preventing blackening of the slot paper. After testing, the broken point remains intact, facilitating precise subsequent repair without causing additional damage.

[0029] Since the core of the motor under test 300 is in a suspended state, it is understandable that an upper insulating support and a lower insulating support are usually provided on the upper and lower ends of the core, respectively. Therefore, when the motor under test is placed in its normal use state, the lower insulating support will insulate the core, so that the core of the motor under test 300 is not directly grounded.

[0030] In some embodiments, the testing device further includes a conductive unit 500; the conductive unit 500 includes a conductive support assembly 510 and a grounding terminal 520 disposed on the conductive support assembly 510; the iron core of the reference motor 400 is in contact with the conductive support assembly 510, and the grounding terminal 520 is connected to the ground terminal of the insulation withstand voltage tester 100 through a ground wire, thereby ensuring the reliable grounding of the iron core of the reference motor 400 by means of the conductive unit 500.

[0031] Furthermore, the conductive support assembly 510 includes a conductive support panel 511 and a conductive support frame 512 disposed on the conductive support panel 511; a grounding terminal 520 is disposed on the conductive support panel 511, and a reference motor 400 is disposed on the conductive support frame 512. The conductive support panel 511 facilitates the overall positional movement and setting of the conductive support assembly 510, while the conductive support frame 512 provides stable support for the reference motor 400, ensuring the reliable grounding effect of the iron core of the reference motor 400.

[0032] Specifically, the conductive support frame 512 includes a metal rod 5121 and a metal seat 5122; one end of the metal rod 5121 is connected to the conductive support panel 511, and the other end of the metal rod 5121 is connected to the metal seat 5122; the metal seat 5122 is a V-shaped structure with its opening facing away from the metal rod 5121. The V-shaped metal seat 5122 can provide good positional stability for the reference motor 400 and ensure stable contact with the iron core of the reference motor 400.

[0033] As is known, the iron core of a motor is typically a cylindrical structure made of stacked silicon steel sheets. Silicon steel sheets have high magnetic permeability, enabling efficient conduction of the magnetic flux required for motor operation and maximizing electromagnetic conversion efficiency. Because the iron core is cylindrical, the metal base 5122 is designed with a V-shaped structure to ensure reliable contact between the iron core and the metal base 5122.

[0034] In some embodiments, the metal base 5122 includes a first contact portion 5122a and a second contact portion 5122b; the included angle between the first contact portion 5122a and the second contact portion 5122b is 120°-130°, which can ensure both good positional stability for the reference motor 400 and stable contact with the iron core of the reference motor 400.

[0035] The reference motor 400 is placed between the first contact portion 5122a and the second contact portion 5122b. The first contact portion 5122a and the second contact portion 5122b limit the reference motor 400. At the same time, the contact between the first contact portion 5122a, the second contact portion 5122b and the outer peripheral surface of the iron core ensures reliable grounding of the iron core.

[0036] This embodiment provides a detection device for the insulation breakage point of a variable frequency motor winding. By introducing a special current limiting and signal modulation unit, namely a reference motor 400, into the test circuit, and ensuring that the iron core of the motor under test 300 is not directly grounded, there will be no damage to the copper wire. Because the iron core of the reference motor 400 is grounded, the discharge between the high-voltage probe 200 and the iron core of the motor under test 300 will not form a large current loop, and the slot paper will not be blackened. This achieves high-sensitivity positioning of the insulation breakage point under high voltage, and limits the current energy flowing through the insulation breakage point to a safe range, avoiding arc erosion or blackening of the insulation material, thus improving the safety and reliability of the detection. In addition, only a normal, intact reference motor is required as the reference unit, without the need for complex electronic circuits, resulting in low implementation cost and easy promotion in factories and repair workshops.

[0037] Example 2: This embodiment makes further structural optimizations based on Embodiment 1. Please refer to... Figure 1 and Figure 2 Based on the above, refer to Figure 3 .

[0038] In this embodiment, the testing device also includes an insulating frame 600; the insulation withstand voltage tester 100, the conductive unit 500 and the motor under test 300 are all mounted on the insulating frame 600, which supports and fixes other components, facilitating the overall use of the testing device.

[0039] The insulating frame 600 has an insulating function, ensuring that when the motor 300 under test is placed on the insulating frame 600, the iron core of the motor 300 under test will not be directly grounded.

[0040] The insulating frame 600 has a flat support surface, which can provide stable support for the insulation withstand voltage tester 100, the conductive unit 500 and the motor under test 300.

[0041] In some embodiments, the testing device further includes an electrical connector 700; the winding output terminal of the reference motor 400 and the winding output terminal of the motor under test 300 are connected via the electrical connector 700. The electrical connector 700 facilitates the connection between the winding output terminal of the reference motor 400 and the winding output terminal of the motor under test 300, and ensures the stability of the connection.

[0042] Typically, windings have three phases: U, V, and W. If the windings of the reference motor 400 and the tested motor 300 are directly connected, the insulation layer needs to be broken first, and then the U, V, and W phases must be connected one by one. While this method achieves the connection, it is cumbersome and prone to unstable connections and poor contact. In this example, the winding outputs of the reference motor 400 and the tested motor 300 are directly connected to the electrical connector 700. This facilitates the connection work for operators and ensures the stability of the connection, thereby ensuring the stability of the testing device.

[0043] Example 3: This embodiment further optimizes the structure based on Embodiment 1. Please refer to [link / reference]. Figures 1-3 .

[0044] In this embodiment, the insulation withstand voltage tester 100 has a current measurement alarm unit; the current measurement alarm unit is used to monitor the leakage current in the circuit. When the leakage current in the circuit exceeds the set threshold of the current measurement alarm unit, the current measurement alarm unit issues an alarm signal to limit the current energy in the circuit within a safe range and avoid damage to the motor 300 under test.

[0045] Furthermore, the current measurement alarm unit has a set threshold of 0.3mA; the high-voltage probe 200 has a test voltage of AC3000V, enabling high-sensitivity positioning of the skin puncture point under high voltage.

[0046] In some implementations, the leakage current of the reference motor 400 is 1.5-1.7 mA. This range of leakage current is sufficient to reliably detect minor insulation defects under AC 3000V high voltage, while the current limiting method through series connection ensures operational and equipment safety, achieving the best balance between detection performance and safety.

[0047] Specifically, after the reference motor 400 is connected in series, the iron core and the winding are equivalent to a capacitor. The current is coupled through the capacitor to form a loop. The magnitude of the current depends on the rate of voltage change. The faster the voltage changes, the larger the coupling current. The leakage current of the motor under test 300 is mainly affected by the reference motor 400 connected in series.

[0048] When a breach exists, the capacitance increases sharply. At the breach, the physical distance between the conductor and the iron core shortens drastically. According to the capacitance law C=εA / d, the decrease in distance d leads to a sharp increase in the local capacitance C at that point. Furthermore, the capacitive current increases significantly. The capacitive current I_C = V / X_C, while the capacitive reactance X_C = 1 / (2πfC). The increase in capacitance C causes a sharp decrease in capacitive reactance X_C, resulting in a significant increase in the capacitive leakage current I_C. When the leakage current exceeds the set threshold of the current measurement alarm unit, the current measurement alarm unit will issue an alarm signal so that the operator can be informed of the detection results.

[0049] The above description is merely an example and illustration of the structure of this invention, and while the description is specific and detailed, it should not be construed as limiting the scope of this invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this invention, and these obvious substitutions all fall within the protection scope of this invention.

Claims

1. A device for detecting the breakage point of a variable frequency motor winding, characterized in that, include: Insulation withstand voltage tester (100); The high-voltage probe (200) is connected to the output end of the insulation withstand voltage tester (100) and is used to contact the winding of the motor (300) under test; The reference motor (400) has its core grounded and connected to the ground terminal of the insulation withstand voltage tester (100). The winding output terminal of the reference motor (400) is connected to the winding output terminal of the motor under test (300). The core of the motor (300) under test is in a suspended state.

2. The detection device for the broken skin point of the winding of a variable frequency motor according to claim 1, characterized in that, It also includes conductive units (500); The conductive unit (500) includes a conductive support assembly (510) and a grounding terminal (520) disposed on the conductive support assembly (510). The iron core of the reference motor (400) is in contact with the conductive support assembly (510), and the grounding terminal (520) is connected to the ground of the insulation withstand voltage tester (100) through a ground wire.

3. The detection device for the broken skin point of the winding of a variable frequency motor according to claim 2, characterized in that, The conductive support assembly (510) includes a conductive support panel (511) and a conductive support frame (512) disposed on the conductive support panel (511). The grounding terminal (520) is disposed on the conductive support panel (511), and the reference motor (400) is disposed on the conductive support frame (512).

4. The detection device for the broken skin point of the winding of a variable frequency motor according to claim 3, characterized in that, The conductive support frame (512) includes a metal rod (5121) and a metal base (5122). One end of the metal rod (5121) is connected to the conductive support panel (511), and the other end of the metal rod (5121) is connected to the metal base (5122). The metal base (5122) is a V-shaped structure with an opening facing away from the metal rod (5121).

5. The detection device for the broken skin point of the winding of a variable frequency motor according to claim 4, characterized in that, The metal base (5122) includes a first contact portion (5122a) and a second contact portion (5122b); The included angle between the first contact portion (5122a) and the second contact portion (5122b) is 120°-130°.

6. The detection device for the broken skin point of the winding of a variable frequency motor according to claim 2, characterized in that, It also includes an insulated frame (600); The insulation withstand voltage tester (100), the conductive unit (500), and the motor under test (300) are all mounted on the insulation frame (600).

7. The detection device for the broken skin point of the winding of a variable frequency motor according to claim 1, characterized in that, It also includes electrical connectors (700); The winding output terminal of the reference motor (400) is connected to the winding output terminal of the motor under test (300) via the electrical connector (700).

8. The detection device for the broken skin point of the winding of a variable frequency motor according to any one of claims 1-7, characterized in that, The insulation withstand voltage tester (100) has a current measurement alarm unit; The current measurement alarm unit is used to monitor the leakage current in the circuit. When the leakage current in the circuit exceeds the set threshold of the current measurement alarm unit, the current measurement alarm unit issues an alarm signal.

9. The detection device for the broken skin point of the winding of a variable frequency motor according to claim 8, characterized in that, The current measurement alarm unit has a set threshold of 0.3mA; The test voltage of the high-voltage probe (200) is AC3000V.

10. The detection device for the broken skin point of the winding of a variable frequency motor according to claim 9, characterized in that, The leakage current of the reference motor (400) is 1.5-1.7 mA.

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