A high-voltage motor winding grounding fault detection device and usage method

Abstract

The present invention relates to a high-voltage motor winding grounding fault detection device and a method for use, comprising a base, a megohmmeter, a clamping assembly, and an infrared imager disposed on the base, the clamping assembly comprising a fixed seat, a driving gear, and a spur rack, the driving gear being rotatably disposed in the fixed seat and meshing with the spur rack, a transmission shaft extending upwardly disposed in the driving gear, the bottom end of a support rod being slidably connected to the base, and the spur rack being pushed up to the support rod for pushing two test pens of the megohmmeter to the stator winding. The present invention utilizes the driving gear to drive the spur gear to be pushed up to the support rod, and the support rod drives the test pens to be pushed up to two detection points of the stator winding that need to be detected, continuously passing a megohmmeter into the coil to measure current, and when the current flows through the grounding point, a thermal effect will occur in the coil and the surrounding iron core due to the large contact resistance of the grounding point, thereby using an infrared imager to perform infrared imaging observation of the inside of the stator winding to accurately find the grounding points in the stator winding slots and slot openings.

Description

Technical Field

[0001] The present invention relates to the technical field of motor fault detection, and in particular to a high-voltage motor winding grounding fault detection device and a use method thereof. Background Art

[0002] Three-phase asynchronous motors are widely used due to their excellent electrical performance and simple structure. However, three-phase asynchronous motors may also suffer from ground faults in the stator slots due to poor stator winding manufacturing process, poor operating conditions or insulation aging. Early ground faults can be discovered by stator AC withstand voltage test, but ground faults are hidden and difficult to identify. The cost of replacing the winding as a whole is high and the maintenance time is long. If not discovered and handled in time, it may cause serious damage to the stator core, increase maintenance costs and extend maintenance time, and affect system safety. Summary of the Invention

[0003] In order to solve the deficiencies in the prior art, the present invention provides a high-voltage motor winding grounding fault detection device and a method for use.

[0004] To achieve the above-mentioned purpose, the present invention is implemented through the following technical solutions: a high-voltage motor winding grounding fault detection device, including a base, on which a megohmmeter, a clamping assembly and an infrared imager are arranged, the clamping assembly includes a fixed seat, a driving gear and a spur rack, the driving gear is rotatably arranged in the fixed seat and meshes with the spur rack, a transmission shaft extending upward is provided in the driving gear, a support rod adapted for a test pen is provided between the fixed seat and the base, the bottom end of the support rod is slidably connected to the base, and the spur rack is pushed to the support rod for pushing the two test pens of the megohmmeter to the stator winding.

[0005] The upper end of the transmission shaft is in the shape of a handle. The transmission shaft and the driving gear are connected by a key. The rotation of the transmission shaft drives the driving gear to rotate. The staff can manually rotate the transmission shaft so that the driving gear drives the spur gear to move laterally. The transmission shaft can also be set as a straight shaft. The output shaft of the external micro-reduction motor drives the transmission shaft to rotate, and the spur gear moves toward the support rod. The support rod is slidably connected to the base. The spur gear pushes the support rod to drive the support rod and the two test pens fixed on the support rod to the position of the stator winding that needs to be tested.

[0006] Preferably, at least two running wheels are provided at the lower portion of the spur rack, and the running wheels are arranged in a second sliding groove provided in the base, and the driving gear drives the spur rack to move toward the support rod through the transmission shaft.

[0007] The length direction of the second slide groove is consistent with the moving direction of the spur rack. The cooperation between the second slide groove and the walking wheel facilitates the straight line movement of the spur rack, thereby reducing the friction between the spur rack and the base.

[0008] Preferably, the transmission shaft passes downward through the driving gear and is rotatably connected to the bottom surface of the fixed seat through the first bearing. The outer ring of the first bearing is connected to the fixed seat, and the inner ring of the first bearing is connected to the transmission shaft.

[0009] Preferably, the base is provided with two first sliding grooves, the length direction of the first sliding grooves is consistent with the moving direction of the spur rack, and the lower end of the support rod is provided with a slider adapted to the first sliding grooves.

[0010] Preferably, a turntable for supporting the stator winding is provided on the base, the turntable and the base are rotatably connected via a second bearing, a threaded hole extending toward the base is provided on one side of the turntable, and a bolt is provided in the threaded hole.

[0011] The turntable is convenient for rotating the stator winding to the position to be measured, and the bolts pass through the threaded holes to the base to fix the turntable.

[0012] Preferably, two support rods are provided, and the two support rods are directly connected by a connecting rod, and the middle part of the connecting rod is connected to one end of the spur gear close to the stator winding.

[0013] Preferably, a baffle is provided on the upper portion of the fixing seat, the baffle is located above the driving gear, the baffle is provided with a circular hole, and the transmission shaft passes through the circular hole to be connected with the driving gear.

[0014] A method for using a high-voltage motor winding grounding fault detection device comprises the following steps:

[0015] S1. Recheck the insulation resistance of the high-voltage motor to confirm that a ground fault has occurred in the high-voltage motor. Disassemble the motor and remove the rotor to eliminate obvious ground faults caused by lead wires and external faults.

[0016] S2. Place the two test pens of the megohmmeter on the support rods respectively. Rotate the transmission shaft so that the driving gear drives the spur gear to the support rod. The support rod drives the test pens to the two test points of the stator winding to be tested. Continue to measure the insulation of the stator winding and pay attention to the voltage value of the megohmmeter.

[0017] S3. Use an infrared imager to continuously observe the stator coil of the motor to find out whether there are obvious hot spots in the core or slot wedges.

[0018] S4. After finding a hot spot, stop applying pressure and perform reliable discharge, then mark the hot spot with a marker, and use an infrared thermometer to verify whether the temperature at this point is significantly higher than other parts.

[0019] Compared with the prior art, the beneficial effects of the present invention are: when the insulation of the motor stator winding is zero, the external lead and other reasons are excluded, and the grounding point in the slot is found using a large-capacity digital insulation megohmmeter and an infrared thermometer;

[0020] The driving gear drives the spur gear to the support rod, and the support rod drives the test pen to the two detection points of the stator winding that need to be tested, so as to avoid the staff holding two test pens in contact with the stator winding for a long time. The head of the existing test pen is an alligator clip test wire head, but due to the different models of stator windings, the alligator clip test wire head cannot be clamped. The test pen is suitable for stator windings of different specifications by tightening it.

[0021] By continuously passing a megohmmeter through the coil to measure the current, the current will generate a thermal effect in the coil and the surrounding iron core due to the large contact resistance of the grounding point when it flows through the grounding point. Therefore, by using an infrared imager to observe the inside of the stator winding by infrared imaging, the grounding points in the stator winding slots and slot openings can be accurately found. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Attachment Figure 1 It is a schematic diagram of the three-dimensional structure of the present invention;

[0023] Attachment Figure 2 The present invention is attached Figure 1 A in the middle is an enlarged structural diagram;

[0024] Attachment Figure 3 This is a schematic diagram of the internal structure of the fixing seat of the present invention;

[0025] Attachment Figure 4 It is a front view of the present invention;

[0026] Attachment Figure 5 The present invention is attached Figure 4 The enlarged structural diagram at B in the middle;

[0027] Attachment Figure 6 This is a circuit diagram of the present invention.

[0028] The numbers shown in the accompanying drawings are: 1. base; 101. first slide; 102. second slide; 2. megohmmeter; 3. fixed seat; 4. driving gear; 5. spur rack; 6. transmission shaft; 7. support rod; 701. slider; 8. stator winding; 9. walking wheel; 10. first bearing; 11. second bearing; 12. test pen; 13. turntable; 14. bolt; 15. connecting rod; 16. baffle; 1601. round hole; 17. infrared imager. DETAILED DESCRIPTION

[0029] The present invention will be further described below with reference to specific embodiments. Figures 1 to 6As shown, a high-voltage motor winding grounding fault detection device includes a base 1, on which a megohmmeter 2, a clamping assembly, and an infrared imager 17 are provided. The clamping assembly includes a fixed base 3, a driving gear 4, and a spur rack 5. The driving gear 4 is rotatably set in the fixed base 3 and meshes with the spur rack 5. An upwardly extending transmission shaft 6 is provided in the driving gear 4. A support rod 7 adapted for a test pen 12 is provided between the fixed base 3 and the base 1. The bottom end of the support rod 7 is slidably connected to the base 1. The spur rack 5 is pushed against the support rod 7 to push the two test pens 12 of the megohmmeter 2 to the stator winding 8. Two support rods 7 are provided, and the two support rods 7 are directly connected by a connecting rod 15. The middle part of the connecting rod 15 is connected to the end of the spur gear near the stator winding 8.

[0030] The upper end of the transmission shaft 6 is in the shape of a handle. The transmission shaft 6 is connected to the driving gear 4 through a key. The rotation of the transmission shaft 6 drives the driving gear 4 to rotate. The staff can manually rotate the transmission shaft 6 so that the driving gear 4 drives the spur gear to move laterally. The transmission shaft 6 can also be set as a straight shaft, which is connected to the output shaft of an external micro-reduction motor to drive the transmission shaft 6 to rotate. The spur gear moves toward the support rod 7. The support rod 7 is slidably connected with the base 1. The spur gear pushes the support rod 7 to drive the support rod 7 and the two test pens 12 fixed on the support rod 7 to the part of the stator winding 8 that needs to be tested.

[0031] Two running wheels 9 are provided at the bottom of the spur rack 5. The running wheels 9 roll in the second chute 102 defined in the base 1. The driving gear 4 drives the spur rack 5 toward the support rod 7 via the transmission shaft 6. The length of the second chute 102 is consistent with the direction of movement of the spur rack 5. The cooperation between the second chute 102 and the running wheels 9 facilitates the linear movement of the spur rack 5, thus reducing the friction between the spur rack 5 and the base 1.

[0032] The transmission shaft 6 passes downward through the driving gear 4 and is rotatably connected to the bottom surface of the fixed seat 3 through the first bearing 10. The outer ring of the first bearing 10 is connected to the fixed seat 3, and the inner ring of the first bearing 10 is connected to the transmission shaft 6.

[0033] The base 1 is provided with two first slide grooves 101 , the length direction of the first slide groove 101 is consistent with the moving direction of the spur rack 5 , and the lower end of the support rod 7 is provided with a slider 701 adapted to the first slide groove 101 .

[0034] A turntable 13 is mounted on the base 1 to support the stator winding 8. The turntable 13 is rotatably connected to the base 1 via a second bearing 11. A threaded hole extending toward the base 1 is defined on one side of the turntable 13, and a bolt 14 is positioned within the threaded hole. This facilitates rotating the stator winding 8 to the position to be measured. Bolts 14 extend through the threaded hole and into the base 1, securing the turntable 13.

[0035] A baffle 16 is provided on the upper portion of the fixing base 3 . The baffle 16 is located above the driving gear 4 . The baffle 16 is provided with a circular hole 1601 . The transmission shaft 6 passes through the circular hole 1601 and is connected to the driving gear 4 .

[0036] A method for using a high-voltage motor winding grounding fault detection device comprises the following steps:

[0037] S1. Recheck the insulation resistance of the high-voltage motor to confirm that a ground fault has occurred in the high-voltage motor. Disassemble the motor and remove the rotor to eliminate obvious ground faults caused by lead wires and external faults.

[0038] S2. Place the two test pens 12 of the megohmmeter 2 on the support rod 7 respectively. Rotate the transmission shaft 6 so that the driving gear 4 drives the spur gear to the support rod 7. The support rod 7 drives the test pens 12 to the two test points of the stator winding 8 to be tested. Continue to measure the insulation of the stator winding 8. Pay attention to the voltage value of the megohmmeter 2. Generally, it should not exceed 50V.

[0039] S3. For high-voltage motors with a capacity of more than 3500kW, a DC high-voltage generator can be used to pressurize the stator winding. The voltage should also be controlled within 50V, and attention should be paid to leakage current.

[0040] S4. After 3 minutes of pressurization, continue to observe the motor stator coil with infrared imaging using an infrared imager 17. If a clear hot spot is found in the core or slot wedge, it means that the stator winding grounding point is in the upper winding at that location. If it is not obvious or cannot be found, continue to observe.

[0041] S5. After finding a hot spot, stop pressurizing and perform reliable discharge, then mark the hot spot with a marker and use an infrared thermometer to verify whether the temperature at this spot is significantly higher than other parts.

[0042] S6. After determining the fault point, formulate a maintenance plan for the motor stator winding according to the location of the fault point and perform repairs.

[0043] It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art may make various changes or modifications to the present invention, and these equivalent forms also fall within the scope limited by the application.

Claims

1. A high-voltage motor winding grounding fault detection device, comprising a base (1), characterized in that: The base (1) is provided with a megohmmeter (2), a pressing assembly and an infrared imager (17); the pressing assembly comprises a fixed seat (3), a driving gear (4) and a spur rack (5); the driving gear (4) is rotatably arranged in the fixed seat (3) and meshes with the spur rack (5); an upwardly extending transmission shaft (6) is arranged in the driving gear (4); a support rod (7) adapted to the test pen (12) is provided between the fixed seat (3) and the base (1); the bottom end of the support rod (7) is slidably connected to the base (1); the spur rack (5) is pushed onto the support rod (7) for pushing the two test pens (12) of the megohmmeter (2) onto the stator winding (8); At least two running wheels (9) are provided at the lower portion of the spur rack (5), and the running wheels (9) are provided in a second sliding groove (102) provided in the base (1). The driving gear (4) drives the spur rack (5) to move toward the support rod (7) via the transmission shaft (6); The transmission shaft (6) passes downward through the driving gear (4) and is rotatably connected to the bottom surface of the fixed seat (3) via the first bearing (10), the outer ring of the first bearing (10) is connected to the fixed seat (3), and the inner ring of the first bearing (10) is connected to the transmission shaft (6); The base (1) is provided with two first slide grooves (101), the length direction of the first slide grooves (101) is consistent with the moving direction of the spur rack (5), and the lower end of the support rod (7) is provided with a slider (701) adapted to the first slide grooves (101); A turntable (13) for supporting the stator winding (8) is provided on the base (1), the turntable (13) and the base (1) being rotatably connected via a second bearing (11), a threaded hole extending toward the base (1) is provided on one side of the turntable (13), and a bolt (14) is provided in the threaded hole; Two support rods (7) are provided, and the two support rods (7) are directly connected via a connecting rod (15). The middle portion of the connecting rod (15) is connected to one end of the spur rack (5) close to the stator winding (8).

2. A high-voltage motor winding grounding fault detection device according to claim 1, characterized in that: A baffle (16) is provided on the upper portion of the fixing seat (3), the baffle (16) is located above the driving gear (4), the baffle (16) is provided with a circular hole (1601), and the transmission shaft (6) passes through the circular hole (1601) and is connected to the driving gear (4).

3. The method for using the high-voltage motor winding grounding fault detection device according to any one of claims 1 to 2, characterized in that: The following steps are included: S1. Review the insulation resistance of the high-voltage motor to confirm that a ground fault has occurred in the high-voltage motor. Disassemble the motor and remove the rotor to eliminate obvious ground faults caused by lead wires and external faults. S2. Place the two test pens (12) of the megohmmeter (2) on the support rod (7) respectively, rotate the transmission shaft (6) so that the driving gear (4) drives the spur rack (5) to push against the support rod (7), and the support rod (7) drives the test pens (12) to push against two detection points of the stator winding (8) to be tested, and continuously perform insulation measurement on the stator winding (8), paying attention to observing the voltage value of the megohmmeter (2); S3, using an infrared imager (17) to continuously observe the stator coil of the motor by infrared imaging, and to find out whether there are obvious hot spots in the core or slot wedge; S4. After finding a hot spot, stop applying pressure and perform reliable discharge, then mark the hot spot with a marker, and use an infrared thermometer to verify whether the temperature at this point is significantly higher than other parts.

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