A transformer core leakage current monitoring device

Abstract

This utility model discloses a transformer core leakage current monitoring device, including a transformer mounted on a transformer support frame, a transformer core mounted on the transformer, and a grounding wire for grounding the transformer core. A transformer core grounding current tester is installed outside the grounding wire, located on one side of the transformer support frame. A tester mounting frame is provided between the tester and the support frame. The tester mounting frame includes a mounting frame, a tester support plate, a current clamp support plate, and movable parts. This utility model allows direct mounting on the transformer support frame via the mounting frame, eliminating the need for on-site drilling and welding. The movable and rotating parts on the mounting frame allow for adjustment of the tester and current clamp's installation position, avoiding repeated climbing and alignment. The operation is simple, reducing manpower compared to traditional temporary binding methods and improving the installation efficiency of the transformer core grounding current tester.

Description

Technical Field

[0001] This utility model relates to, but is not limited to, the field of transformer monitoring technology, and more specifically, to a transformer core leakage current monitoring device. Background Technology

[0002] The transformer core is made of laminated silicon steel sheets. During operation, the inter-sheet insulation coating may be damaged locally due to thermal aging, mechanical stress, or overvoltage, leading to inter-sheet short circuits. The short-circuit eddy currents form a floating potential inside the core, which forms a capacitive / resistive path to ground through the core clamps, foundation channel steel, and other structural components. This ultimately manifests as a ground leakage current with a frequency of 50 Hz and a milliampere level. This current is discharged along the path of core-clamps-grounding down conductor-main grounding grid. Therefore, the grounding down conductor is the only external discharge channel for the core leakage current.

[0003] In power system operation and maintenance, to monitor the insulation condition of transformer cores, it is necessary to periodically conduct live-line testing of leakage current in the grounding leads. Traditionally, portable clamp-on ammeters are manually lifted or temporarily strapped to angle iron, with the sensor jaws clamping the grounding wire. Since there are no dedicated fixed points on site, workers often have to carry ladders and climb multiple times to drill holes, weld supports, or secure wires in narrow, high places, which is time-consuming and poses a risk of falls from height. Therefore, a more convenient transformer core leakage current monitoring device is designed. Utility Model Content

[0004] The technical problem to be solved by this utility model is to overcome the defects of the prior art and provide a transformer core leakage current monitoring device.

[0005] To solve the above-mentioned technical problems, this utility model provides the following technical solution: This utility model discloses a transformer core leakage current monitoring device, including a transformer mounted on a transformer support frame, a transformer core mounted on the transformer, and a grounding wire for grounding the transformer core. A transformer core grounding current tester is installed outside the grounding wire. The transformer core grounding current tester is located on one side of the transformer support frame. A tester mounting frame is provided between the transformer core grounding current tester and the support frame. The tester mounting frame includes a mounting frame, a tester support plate located on the front side of the mounting frame, a current clamp support plate located on the top side of the mounting frame, and a movable component for connecting the transformer core grounding current tester.

[0006] Preferably, the mounting frame has a "U" shaped design, the mounting frame is screwed to the transformer support frame, a connecting plate is provided between the tester support plate and the mounting frame, the connecting plate is bolted to the mounting frame and rotatably connected to one end of the tester support plate, and the current clamp support plate is rotatably connected to the mounting frame.

[0007] Preferably, both the tester support plate and the current clamp support plate are provided with movable parts, the movable parts including a movable plate and a mounting plate, and rotating parts are provided on the rear side of the mounting plate and the front side of the movable plate.

[0008] Preferably, the movable plate is provided with sliders at the four rear corners. The sliders are cylindrical in design. The surfaces of the tester support plate and the current clamp support plate are provided with movable grooves for the movable plate to move. The size of the movable plate on the current clamp support plate is the same as that of the current clamp support plate.

[0009] Preferably, the rotating component includes several fixed plates with arc-shaped ends. The front side of the movable plate and the rear side of the mounting plate are screwed to the fixed plates. At least three fixed plates are provided on the movable plate, and there is a gap between adjacent fixed plates. At least two fixed plates are provided on the mounting plate.

[0010] Preferably, the fixed plate on the mounting plate is inserted into the fixed plate on the movable plate with a gap and is rotatably connected, and the mounting plate is screwed to the transformer core grounding current tester.

[0011] Preferably, the transformer core grounding current tester is provided with a tester protective baffle on the top outer side. The tester protective baffle is arc-shaped and has inclined surfaces on the front and rear sides.

[0012] Preferably, the top of the protective baffle of the tester is provided with a through hole for connecting wires, and a locking block is threaded on the inner side near the bottom of the protective baffle of the tester. The locking block is rotatably connected to the transformer core grounding current tester.

[0013] Preferably, the transformer core grounding current tester includes a current clamp for holding the grounding wire, the surface of the transformer core grounding current tester is provided with a display screen, and the top of the transformer core grounding current tester is provided with a current clamp interface.

[0014] Preferably, the current clamp is provided with an output lead, which passes through the protective baffle of the tester and is electrically connected to the current clamp interface.

[0015] Compared with the prior art, the beneficial effects of this utility model are as follows: This utility model allows for direct mounting on the transformer support frame via a mounting frame, eliminating the need for on-site drilling and welding. Furthermore, the movable and rotating parts on the mounting frame allow for adjustment of the installation position of the tester and current clamp, avoiding repeated climbing and alignment. The operation is simple, reducing manpower compared to traditional temporary binding methods and improving the installation efficiency of the transformer core grounding current tester.

[0016] To more clearly illustrate the embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0017] The structures, proportions, sizes, etc. illustrated in this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed herein, and are not intended to limit the implementation conditions of this utility model. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effects and objectives that this utility model can produce, should still fall within the scope of the technical content disclosed in this utility model. Attached Figure Description

[0018] The accompanying drawings are provided to further illustrate the present invention and form part of the specification. They are used together with the embodiments of the present invention to explain the present invention, but do not constitute a limitation thereof. In the drawings: Figure 1 This is a schematic diagram of the overall structure of this utility model; Figure 2 This is an enlarged view of part A of the overall structural schematic diagram of this utility model; Figure 3 This is a schematic diagram of the transformer core grounding current tester of this utility model; Figure 4 This is a structural schematic diagram of the tester mounting bracket of this utility model; In the diagram: 1. Transformer core; 2. Transformer support frame; 3. Grounding wire; 4. Transformer core grounding current tester; 41. Display screen; 42. Current clamp interface; 43. Current clamp; 44. Output lead; 5. Tester mounting bracket; 51. Mounting frame; 52. Connecting plate; 53. Tester support plate; 54. Current clamp support plate; 55. Movable plate; 56. Mounting plate; 57. Fixed plate; 58. Movable slot; 6. Tester protective baffle; 61. Sloping surface; 62. Connection wire through hole; 63. Locking block. Detailed Implementation

[0019] like Figure 1-4As shown, this utility model provides a transformer core 1 leakage current monitoring device, including a transformer installed on a transformer support frame 2, a transformer core 1 installed on the transformer, and a grounding wire 3 for grounding the transformer core 1. A transformer core grounding current tester 4 is installed outside the grounding wire. The transformer core grounding current tester 4 is located on one side of the transformer support frame 2. A tester mounting frame 5 is provided between the transformer core grounding current tester 4 and the support frame. The tester mounting frame 5 includes a mounting frame 51, a tester support plate 53 located on the front side of the mounting frame 51, a current clamp support plate 54 located on the top side of the mounting frame 51, and a movable part for connecting the transformer core grounding current tester 4.

[0020] Furthermore, in this embodiment, the mounting frame 51 has a "U" shape design. The mounting frame 51 is screwed to the transformer support frame 2. The shape of the mounting frame 51 facilitates its installation on the transformer mounting frame. A connecting plate 52 is provided between the tester support plate 53 and the mounting frame 51. The connecting plate 52 is bolted to the mounting frame 51 and rotatably connected to one end of the tester support plate 53. The current clamp support plate 54 is rotatably connected to the mounting frame 51. The tester support plate 53 is installed on the mounting frame 51 through the connecting plate 52. The usage direction of both the tester support plate 53 and the current clamp support plate 54 can be adjusted and fixed by bolts / screws, improving convenience and adaptability.

[0021] It should be noted that the dimensions and shapes of the mounting frame 51, the current clamp support plate 54, and the tester support plate 53 are adapted to the shape of the transformer mounting bracket.

[0022] In this embodiment, both the tester support plate 53 and the current clamp support plate 54 are provided with movable parts. The movable parts include a movable plate 55 and a mounting plate 56. Rotating parts are provided on the rear side of the mounting plate 56 and the front side of the movable plate 55. The mounting plate 56 can be rotated on the front side of the movable plate 55 by means of the rotating parts.

[0023] In this embodiment, sliders are provided at the four rear corners of the movable plate 55. The sliders are cylindrical in design. The surfaces of the tester support plate 53 and the current clamp support plate 54 are both provided with movable grooves 58 for the movable plate 55 to move. The movable plate 55 can move horizontally within the movable grooves 58 on the support plate by means of the sliders, so as to adjust its position and facilitate the viewing of the test values ​​of the tester and the installation of the current clamp 43. The size of the movable plate 55 on the current clamp support plate 54 is consistent with that of the current clamp support plate 54.

[0024] It should be noted that the movable plate 55 is fixed to the tester support plate 53 and the current clamp support plate 54 by bolts. After the position is determined, the bolts are passed from top to bottom through the top of the tester support plate 53 or the current clamp support plate 54 to fix the position of the movable plate 55.

[0025] In this embodiment, the rotating component includes several fixed plates 57 with arc-shaped ends. Fixed plates 57 are screwed to the front side of the movable plate 55 and the rear side of the mounting plate 56. At least three fixed plates 57 are provided on the movable plate 55, and there is a gap between adjacent fixed plates 57. At least two fixed plates 57 are provided on the mounting plate 56.

[0026] In this embodiment, the fixed plate 57 on the mounting plate 56 and the fixed plate 57 on the movable plate 55 are interlocked and rotated together. The mounting plate 56 and the movable plate 55 are connected together by the fixed plate 57. After the mounting plate 56 is adjusted at the angle, it is fixed in position by bolts / screws, so that the angle of the tester or current clamp 43 can be adjusted, which can better perform tester inspection / grounding wire 3 connection. The mounting plate 56 is screwed to the transformer core grounding current tester 4 and the current clamp 43, and the mounting plate 56 under the current clamp 43 is staggered from its clamping part to avoid conflict.

[0027] In this embodiment, a protective baffle 6 is provided on the top outer side of the transformer core grounding current tester 4. Considering the environment in which the transformer core grounding current tester 4 is exposed, the protective baffle 6 provides shielding protection. The protective baffle is arc-shaped, and inclined surfaces 61 are provided on the front and rear sides of the protective baffle 6. The inclined surfaces 61 facilitate rainwater to flow down and not accumulate on the protective baffle 6.

[0028] It should be noted that the material selection for the protective baffle 6 of the tester must ensure that it will not affect the monitoring of the tester.

[0029] In this embodiment, the top of the tester protective baffle 6 is provided with a connecting wire through hole 62. The output lead 44 can easily pass through the tester protective baffle 6 through the connecting wire through hole 62 and connect to the current clamp interface 42. A locking block 63 is threaded on the inner side near the bottom of the tester protective baffle 6. The locking block 63 is rotatably connected to the transformer core grounding current tester 4. The tester protective baffle 6 is installed on the top of the tester through the locking block 63, and the shielding angle can be adjusted. The angle / position can be fixed by screws / bolts to achieve effective protection for the tester.

[0030] In this embodiment, the transformer core grounding current tester 4 includes a current clamp 43 for clamping the grounding wire 3. The test is performed by clamping the current clamp 43 onto the grounding wire 3. The surface of the transformer core grounding current tester 4 is provided with a display screen 41, which displays the monitored current value. The top of the transformer core grounding current tester 4 is provided with a current clamp interface 42.

[0031] In this embodiment, the current clamp 43 is provided with an output lead 44, which passes through the protective baffle 6 of the tester and is electrically connected to the current clamp interface 42. The connection between the current clamp 43 and the transformer core grounding current tester 4 is realized through the output lead 44 and the current clamp interface 42.

[0032] It should be noted that the sampling principle of the current clamp 43 is as follows: The current clamp 43 has a built-in Hall sensor that is sensitive to magnetic fields. The surface of the Hall sensor is covered with a permalloy magnetic ring. When the grounding wire 3 is passed through the clamp jaws, the leakage current of the iron core generates an alternating magnetic field of the same frequency around the wire. The magnetic ring concentrates the magnetic field onto the Hall sensor. The Hall sensor immediately outputs a millivolt-level voltage signal that is proportional to the strength of the magnetic field. After differential amplification and 50 Hz bandpass filtering, only the power frequency component corresponding to the leakage current remains, which is then sent to the subsequent circuit for processing.

[0033] Specifically, this device uses the grounding wire 3, which is led out from a single point on the iron core, as the sampling point. According to Ampere's circuital law, the leakage current passing through the grounding wire 3 is proportional to the degree of insulation defects inside the iron core. By inserting a non-contact current clamp 43 in series with the open-circuit grounding wire 3, the waveform can be obtained without loss, without modifying the original grounding system, ensuring that the iron core remains reliably grounded at a single point. The monitoring and usage steps of the transformer iron core 1 leakage current monitoring device are as follows: Before installation, perform a safety check. Secure the mounting frame 51 onto the crossbar of the transformer support frame 2 with screws. The opening of the mounting frame 51 should avoid the transformer heat sink or other obstacles. Fix the connecting plate 52 to the front of the mounting frame 51 with bolts. Then connect the tester support plate 53 and tighten the bolts. Rotate the current clamp support plate 54 to be parallel to the grounding wire 3 (to facilitate subsequent clamping operations) and fix the bolts. Slide the movable plate 55 of the tester support plate 53 to the left (avoiding the high temperature area of ​​the transformer), tighten the top bolts to fix it, the current clamp support plate 54 reserves the clamping space of the current clamp 43, align the screw holes on the back of the transformer core grounding current tester 4 with the mounting plate 56, fix it with screws, ensure that the screen faces outward, the mounting plate 56 needs to be adjusted in advance by rotating the parts to avoid glare; Connect the bottom screw hole of the current clamp 43 to the mounting plate 56 of the current clamp support plate 54, stagger the clamping parts (to avoid interference when the grounding wire 3 is inserted), tighten the screw, insert the baffle block 63 into the threaded hole on the top of the tester, adjust the arc baffle to cover the top of the tester, to prevent rain and not affect heat dissipation, tighten the screw, and pass the output lead 44 through the hole on the top of the baffle, leaving a 10cm margin, and fix it to the edge of the hole with insulating tape to prevent wear; Insert the plug of the output lead 44 of the current clamp 43 into the current clamp interface 42 on the top of the tester. Check that the lead is not crossed or compressed. Secure it to the bracket with a cable tie. Open the jaws of the current clamp 43 and slip the grounding wire 3 of the transformer core 1 (10cm from the root of the core) onto it. Ensure that the jaws are tightly closed with no visible gaps. The grounding wire 3 should be in the center of the jaws to avoid skewness that could cause errors. Press the power button on the tester for 3 seconds. The display screen 41 will enter the monitoring interface. The current leakage current value is displayed as 0.00mA (when there is no grounding current). Record the leakage current value (unit: mA) displayed on the screen every 1 hour (the time is for illustrative purposes only, and the specific interval should be selected according to the actual situation). If the value is >50mA (example threshold, adjusted according to the procedure), an alarm will be triggered immediately and the tester will sound a buzzer (the tester collects the amplified voltage signal 1,000 times per second, records the data for 20 milliseconds, and calculates the effective value of this waveform using the root mean square algorithm, which is the current leakage current value. The calculated result is compared with the threshold set inside the instrument. If the value measured for three consecutive seconds exceeds this threshold, the main board will immediately drive the buzzer to sound an alarm). In case of extreme weather, check the protective barrier after heavy rain to ensure there is no water accumulation. If the barrier is tilted too much, readjust the 63 screws of the locking block. When the temperature is high (>40℃), use an infrared thermometer to check the temperature of the tester's outer casing. If it is >70℃, add a temporary sunshade. Regular maintenance: After powering off, wipe the tester screen and baffle with a dry, soft cloth to remove salt spray / dust (once a week in coastal areas), check all screws for rust (especially the grounding wire 3 connection), spray with rust inhibitor and tighten again; When disassembly is required, disconnect the jaws of the current clamp 43, pull out the output lead 44, unscrew the protective baffle block 63, remove the screws from the tester and mounting plate 56, remove the current clamp 43, loosen the support plate bolts, and finally remove the mounting frame 51.

[0034] In addition, when the grounding wire 3 may be superimposed with power frequency current (ampere level) and high-order harmonics caused by load imbalance, those skilled in the art usually use a double-layer permalloy shielding ring at the head of the current clamp 43. The high-frequency suppression ratio for >100 kHz is ≥60dB. A third-order IIR 50 Hz bandpass filter with a bandwidth of ±5 Hz is added to the digital part. The signal attenuation for signals below 49 Hz and above 51 Hz is ≥40 dB. This ensures that only the 50 Hz component of the core leakage current is included in the leakage current, effectively eliminating load current and harmonic interference.

[0035] The components of this utility model, such as the transformer core 1, grounding wire 3, and transformer core grounding current tester 4, are all general standard parts or parts known to those skilled in the art. Their structure and principle can be learned by those skilled in the art through technical manuals or conventional experimental methods.

[0036] In the description of this utility model, it should be understood that the terms "coaxial", "bottom", "one end", "top", "middle", "other end", "upper", "side", "top", "inner", "front", "center", "both ends", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. They are only for the convenience of describing this utility model 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. Therefore, they should not be construed as limitations on this utility model.

[0037] Furthermore, the terms “first,” “second,” “third,” and “fourth” are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as “first,” “second,” “third,” or “fourth” may explicitly or implicitly include at least one of those features.

[0038] In this utility model, unless otherwise explicitly specified and limited, the terms "installation", "setting", "connection", "fixing", "screw connection", etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two components or the interaction between two components. Unless otherwise explicitly limited, those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0039] Finally, it should be noted that the above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A transformer core (1) leakage current monitoring device comprising a transformer installed on a transformer support frame (2), a transformer core (1) installed on the transformer, and a ground wire (3) for grounding the transformer core (1), characterized in that, A transformer core grounding current tester (4) is provided outside the grounding wire. The transformer core grounding current tester (4) is located on one side of the transformer support frame (2). A tester mounting frame (5) is provided between the transformer core grounding current tester (4) and the support frame. The tester mounting frame (5) includes a mounting frame (51), a tester support plate (53) located in front of the mounting frame (51), a current clamp support plate (54) located on the top side of the mounting frame (51), and a movable part for connecting the transformer core grounding current tester (4).

2. A transformer core (1) leakage current monitoring device according to claim 1, characterized in that, The mounting frame (51) is U-shaped. The mounting frame (51) is screwed to the transformer support frame (2). A connecting plate (52) is provided between the tester support plate (53) and the mounting frame (51). The connecting plate (52) is bolted to the mounting frame (51) and rotatably connected to one end of the tester support plate (53). The current clamp support plate (54) is rotatably connected to the mounting frame (51).

3. A transformer core (1) leakage current monitoring device according to claim 2, characterized in that, Both the tester support plate (53) and the current clamp support plate (54) are provided with movable parts, including a movable plate (55) and a mounting plate (56). Rotating parts are provided on the rear side of the mounting plate (56) and the front side of the movable plate (55).

4. The transformer core (1) leakage current monitoring device according to claim 3, characterized in that, The movable plate (55) is provided with sliders at the four rear corners. The sliders are cylindrical. The surfaces of the tester support plate (53) and the current clamp support plate (54) are provided with movable grooves (58) for the movable plate (55) to move. The size of the movable plate (55) on the current clamp support plate (54) is the same as that of the current clamp support plate (54).

5. A transformer core (1) leakage current monitoring device according to claim 4, characterized in that, The rotating component includes several fixed plates (57) with arc-shaped ends. The front side of the movable plate (55) and the rear side of the mounting plate (56) are screwed to the fixed plates (57). At least three fixed plates (57) are provided on the movable plate (55), and there is a gap between adjacent fixed plates (57). At least two fixed plates (57) are provided on the mounting plate (56).

6. A transformer core (1) leakage current monitoring device according to claim 5, characterized in that, The fixed plate (57) on the mounting plate (56) is inserted into the gap of the fixed plate (57) on the movable plate (55) and rotated. The mounting plate (56) is screwed to the transformer core grounding current tester (4).

7. A transformer core (1) leakage current monitoring device according to claim 6, characterized in that, The transformer core grounding current tester (4) is provided with a tester protective baffle (6) on the top outer side. The test protective baffle is arc-shaped and has inclined surfaces (61) on the front and back sides.

8. A transformer core (1) leakage current monitoring device according to claim 7, characterized in that, The top of the protective baffle (6) of the tester is provided with a through hole (62) for connecting wires, and a locking block (63) is threaded on the inner side near the bottom of the protective baffle (6). The locking block (63) is rotatably connected to the transformer core grounding current tester (4).

9. A transformer core (1) leakage current monitoring device according to claim 8, characterized in that, The transformer core grounding current tester (4) includes a current clamp (43) for clamping the grounding wire (3), a display screen (41) is provided on the surface of the transformer core grounding current tester (4), and a current clamp interface (42) is provided on the top of the transformer core grounding current tester (4).

10. A transformer core (1) leakage current monitoring device according to claim 9, characterized in that, The current clamp (43) is provided with an output lead (44), which passes through the protective baffle (6) of the tester and is electrically connected to the current clamp interface (42).

Images