Miniaturized on-load voltage regulation switch and on-load voltage regulation distribution transformer

Abstract

The utility model discloses a miniaturized on-load voltage regulation switch and an on-load voltage regulation distribution transformer, the switch comprises a driving mechanism assembly, a transmission mechanism assembly, a selection switch assembly, a change-over switch assembly, a transition element and an insulation installation mainboard, the driving mechanism assembly comprises a servo motor, a gearbox, a driving cam disc, a transmission gear and a driving deflector rod wheel, the transmission mechanism assembly comprises a groove strip, a linkage mechanism and a transmission shaft, the servo motor drives the groove strip, the linkage mechanism and the transmission shaft to act in a timing sequence by means of the gearbox, the driving cam disc, the transmission gear and the driving deflector rod wheel, then the selection switch assembly and the change-over switch assembly are driven to act, and conversion of voltage regulation gears is completed. A linear mechanism design is adopted, the structure is simple and compact, the conventional size of the distribution transformer hardly needs to be changed when the distribution transformer is installed, a bridging principle can be adopted, a non-excitation switch is directly replaced by an on-load voltage regulation switch, and the on-load voltage regulation switch is used for directly transforming the non-excitation distribution transformer into the on-load voltage regulation distribution transformer.

Description

Technical Field

[0001] This device relates to the field of power product technology, and more specifically, to a miniaturized on-load tap changer and an on-load tap changer distribution transformer. Background Technology

[0002] Distribution transformers are the last stage transformers in the power grid, used in all sectors of the national economy and people's livelihood, and are ubiquitous in urban and rural areas. Currently, all distribution transformers use off-load tap changer methods. Tap change requires disconnecting the power supply first, then manually adjusting the off-load tap changer switch, and finally restoring power. Because this requires a power outage for tap change and cannot be done promptly, distribution transformers in actual power grids are essentially without tap changer measures. This results in low voltage qualification rates, poor stability, and abnormal operation of electrical equipment, leading to increased losses for both the distribution transformer itself and the equipment. With the continuous development of the social economy and power grid, the requirements for voltage quality will become increasingly stringent, thus placing higher demands on the reliability of on-load tap-changing distribution transformers. The core component of on-load tap-changing distribution transformers is the on-load tap changer switch, which requires even higher standards.

[0003] In recent years, there have been cases of applying on-load tap changers (OTCs) from main transformers to distribution transformers for on-load tap regulation. However, the large size and regular maintenance of TTCs from main transformers make them unsuitable for the reliability requirements of distribution transformers, especially given their large number. On-load tap changers using spring energy storage and permanent magnet / electromagnetic drive methods are also available for distribution transformers. While these also employ vacuum arc extinguishing, the high impact force during drive transmission affects the lifespan of related components, preventing them from meeting the design lifespan of the distribution transformer and making them unsuitable for use in a large number of distribution transformers. Furthermore, since most existing distribution transformers are non-excited, replacing them all with TTC-regulated transformers would be very costly. Therefore, a miniaturized TTC switch suitable for both retrofitting existing distribution transformers and new TTC-regulated distribution transformers has been proposed to address these market challenges.

[0004] MR GmbH of Germany has filed the following Chinese utility model patent applications: 1. Application No. 201380020207.9, entitled "On-load tap changer"; 2. Application No. 201380020450.0, entitled "On-load tap changer"; 3. Application No. 201380020742.4, entitled "On-load tap changer"; 4. Application No. 201380020745.8, entitled "On-load tap changer". The core of these four utility model patents is the ability to operate not only the selector contact unit but also the switching device for uninterrupted on-load switching, without the need for an intermediate accumulator, using a bevel gear transmission device and a common motor drive. However, the transmission and control mechanisms of the aforementioned four patents are complex and costly. Furthermore, none of their designs address the lifespan and maintenance of on-load tap changers. Given the high reliability requirements of distribution transformers, on-load tap changers necessitate even higher reliability standards. Additionally, their design principles and structures cannot be directly applied to the on-load tap-changing retrofit of domestic off-grid distribution transformers. Using these switches for retrofitting would significantly increase the cost.

[0005] Jinan Aidi Electric Equipment Co., Ltd. has applied for a Chinese utility model patent with the following application number: Application No.: 201710019736.7. It mainly addresses the problem of complex structure and high cost of the original on-load tap changer on the market, simplifies the structure and solves the problem of regular maintenance. Its design structure and principle cannot be directly used for the on-load tap changer retrofit of domestic non-excitation distribution transformers. If its switch is used for retrofit, the retrofit cost will be greatly increased. Summary of the Invention

[0006] The purpose of this invention is to provide a miniaturized on-load tap changer and on-load tap-changing distribution transformer, solving the problem of periodic maintenance required for existing on-load tap-changing distribution transformers due to on-load tap-changing switching. It also addresses the issues of large size and inconvenient installation of existing on-load tap changers, achieving miniaturization of the on-load tap changer so that its installation does not require changes to the size and shape of a conventional distribution transformer. This results in a long lifespan and maintenance-free characteristics for the on-load tap changer, making its lifespan equal to that of the distribution transformer itself. Furthermore, the design of the miniaturized on-load tap changer is upgraded based on the principle of the off-load tap changer used in existing off-load distribution transformers.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A miniaturized on-load tap changer, characterized in that it includes a drive mechanism assembly, a transmission mechanism assembly, a selector switch assembly, a switching assembly, a transition element, and an insulated mounting main board, wherein the selector switch assembly, the switching assembly, and the transition element each have three phases;

[0009] The drive mechanism assembly includes a servo motor, a gearbox, a drive cam disc, a transmission gear, and a drive lever wheel;

[0010] The transmission mechanism assembly includes a grooved bar, a linkage mechanism, and a transmission shaft;

[0011] Each phase of the selector switch assembly includes a guide rod, a moving contact assembly, a stationary contact assembly, and an insulating support;

[0012] The three-phase switching assembly includes a drive arm, a mounting bracket, and a vacuum interrupter. The vacuum interrupter has three phases, and the three-phase vacuum interrupters operate under the drive of the same drive arm.

[0013] The servo motor is connected to the gearbox and is mounted on the gearbox.

[0014] The drive cam disc, the transmission gear, and the drive lever wheel are all mounted at the bottom of the gearbox;

[0015] The groove is mounted on the linkage mechanism, and the linkage mechanism is mounted on the insulating mounting main board;

[0016] The three-phase selection switch assembly, the switching switch assembly, and the transition element are all mounted on the insulating mounting main board;

[0017] The servo motor drives the gearbox, which in turn rotates the drive cam disc. The drive cam disc then drives the transmission gear, which in turn drives the drive lever wheel. The drive cam disc, via the transmission shaft, drives the drive cross arm, which in turn drives the three-phase vacuum interrupter to switch gears. The drive lever wheel drives the slotted bar, which in turn drives the linkage mechanism. The linkage mechanism then drives the moving contact assembly to select the corresponding stationary contact in the stationary contact assembly for electrical connection, thus completing gear selection.

[0018] According to a preferred embodiment of the present invention, a gear is provided on the drive cam disk, the gear meshes with the transmission gear, and the rotation of the gear drives the transmission gear to rotate; different cams and grooves are provided in the drive cam disk, and the transmission shaft drives the vacuum interrupter to move in sequence with the movement of the grooves.

[0019] According to a preferred embodiment of the present invention, the drive lever wheel is provided with a lever and a limiting block. The drive lever wheel drives the grooved bar to move linearly through the lever, thus converting the rotation of the drive lever wheel into the linear motion of the grooved bar. After the gear selection is completed, the limiting block engages with a certain tooth on the grooved bar for positioning and limiting.

[0020] According to a preferred embodiment of the present invention, the drive cam disc and the drive lever wheel rotate synchronously, respectively driving the switching switch assembly and the selection switch assembly to perform sequential actions to complete the switching of the voltage regulation gear.

[0021] According to a preferred embodiment of the present invention, the linkage mechanism includes a linear guide rail, a linkage screw, and three sliders. The groove is fixed on the linkage screw. The linear guide rail and the linkage screw are both fixedly connected to the sliders. The linear guide rail is fixedly mounted on the insulating mounting main board through two linear guide blocks on it. The sliders drive the moving contact assembly to move linearly.

[0022] According to a preferred embodiment of the present invention, the moving contact assembly includes two moving contacts and a moving contact seat. The moving contacts are mounted on the moving contact seat, and the moving contact seat is mounted on the guide rod. The moving contact seat moves linearly on the guide rod, and the guide rod is fixedly mounted on the insulating bracket. The stationary contact assembly includes a plurality of stationary contacts arranged in a straight line and a stationary contact integrated seat. The plurality of stationary contacts are mounted and fixedly mounted on the stationary contact integrated seat, and the stationary contact integrated seat is fixedly connected to the insulating bracket and the insulating mounting main board by fixing studs.

[0023] According to a preferred embodiment of the present invention, protrusions are provided on the upper and lower sides of the integrated stationary contact base. The protrusions are located outside the gap between the stationary contacts. The plane of the protrusion on the upper side of the integrated stationary contact base is higher than the upper plane of the stationary contact, and the plane of the protrusion on the lower side of the integrated stationary contact base is lower than the lower plane of the stationary contact.

[0024] According to a preferred embodiment of the present invention, the three-phase vacuum interrupters are arranged in a straight line, a three-phase tripping arm is provided on the drive cross arm, and the moving contact portion of the vacuum interrupter is fixedly connected to the drive cross arm through the tripping arm; a three-phase interrupter mounting base is provided on the mounting bracket, and the stationary contact portion of the vacuum interrupter is fixedly mounted on the mounting bracket through the interrupter mounting base.

[0025] According to a preferred embodiment of the present invention, there are two drive arms and two mounting brackets. The two drive arms are connected and fixed by two connecting blocks. The transmission shaft is connected to one of the connecting blocks, which drives the connecting block to move laterally, thereby driving the drive arms to move laterally. The two drive arms move between the two mounting brackets, and the mounting brackets have a guiding function for the drive arms.

[0026] An on-load tap-changing distribution transformer, characterized in that it employs a miniaturized on-load tap-changing switch as described above, comprising a main tap-changing circuit and a transition circuit. During normal operation, the main tap-changing circuit is in a conducting state, and the transition circuit is in a disconnected state. When switching tap levels, the switching assembly operates sequentially, causing the transition circuit to conduct first and the main tap-changing circuit to disconnect. Then, the two moving contacts in the moving contact assembly of the selection switch assembly select the corresponding stationary contact in the stationary contact assembly for connection, completing the selection of the tap level. The switching assembly also operates sequentially, causing the main tap-changing circuit to conduct and the transition circuit to disconnect, completing the tap level switching. The transformer employs a cross-current switching mechanism. In the first principle, the transition circuit is fixed at a certain tap position of the transformer's regulating winding. In the main regulating circuit, the two moving contacts of the miniaturized on-load tap changer's moving contact assembly are electrically connected to the two corresponding stationary contacts in the stationary contact assembly. The two stationary contacts are electrically connected to the two corresponding taps of the transformer's high-voltage coil regulating winding. In the second principle, the transition circuit changes step-by-step with the main regulating circuit. In the main regulating circuit, the two moving contacts of the miniaturized on-load tap changer's moving contact assembly are electrically connected to one of the corresponding stationary contacts in the stationary contact assembly. The stationary contact is electrically connected to a corresponding tap of the transformer's high-voltage coil regulating winding.

[0027] Compared to existing technologies, the advantages of this utility model are as follows: It provides a miniaturized on-load tap changer, installed on the cover of a distribution transformer tank. The switch body is located below the cover, while the servo motor driving the switch is located above the cover. The miniaturized on-load tap changer, when installed in the distribution transformer, minimizes changes to the shape and volume of the conventional transformer, significantly reducing production costs associated with a large switch size. It achieves fault-free, maintenance-free continuous voltage regulation for over 300,000 cycles, remaining maintenance-free throughout the transformer's lifespan, thus improving the reliability of on-load tap regulation. Furthermore, it allows for the direct replacement of the non-excitation tap changer in a non-excitation distribution transformer with the miniaturized on-load tap changer, transforming it into an on-load tap-changing distribution transformer without altering the original transformer's volume or coil wiring. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the overall structure of a miniaturized on-load tap changer according to this utility model;

[0029] Figure 2 This is a schematic diagram A of the overall structure of a miniaturized on-load tap changer without its housing, according to this utility model;

[0030] Figure 3 This is a schematic diagram (B) of the overall structure of a miniaturized on-load tap changer without its housing, according to this utility model.

[0031] Figure 4 This is a schematic diagram (C) of the overall structure of a miniaturized on-load tap changer without its housing, according to this utility model.

[0032] Figure 5 This is a schematic diagram of the structure of a miniaturized on-load tap changer without the drive mechanism component of this utility model;

[0033] Figure 6 This is a schematic diagram of the structure of a switching assembly for a miniaturized on-load tap changer according to this utility model;

[0034] Figure 7 This is a schematic diagram of the structure of a drive mechanism assembly for a miniaturized on-load tap changer according to this utility model.

[0035] Figure 8 This is a schematic diagram of the linear voltage regulation principle and voltage regulation timing of a miniaturized on-load tap changer according to this utility model.

[0036] Figure 9 This utility model presents a schematic diagram of the timing of the voltage regulation action of a miniaturized on-load tap changer that can be directly used for the transformation of non-excitation distribution transformers. Detailed Implementation

[0037] The present invention will be further described below with reference to the accompanying drawings. The embodiments described below are only used to more clearly illustrate the technical solution of the present invention, and are selected embodiments of the present invention, not all embodiments, and should not be used to limit the protection scope of the present invention. All other embodiments obtained by those skilled in the art without inventive effort are within the protection scope of the present invention.

[0038] See Figures 1-7This utility model discloses a miniaturized on-load tap changer, comprising a drive mechanism assembly 1, a transmission mechanism assembly 2, a selector switch assembly 3, a switching switch assembly 4, a transition element 5, and an insulating mounting plate 6. Each of the selector switch assembly 3, switching switch assembly 4, and transition element 5 has three phases. Insulating housings 7.1 and 7.2 are provided on the exterior of the selector switch assembly 3 and switching switch assembly 4. The transition element 5 is located outside the insulating housing 7.2 and is fixed to the insulating mounting plate 6 by fixing studs. The drive mechanism assembly 1 includes a servo motor 1.1, a gearbox 1.2, a drive cam disc 1.3, a transmission gear 1.4, and a drive lever wheel 1.5. The transmission mechanism assembly 2 includes a groove 2.1, a linkage mechanism 2.2, and a drive shaft 2.3. Each phase selector switch assembly 3 includes a guide rod 3.1, a moving contact assembly 3.2, a stationary contact assembly 3.3, and an insulating bracket 3.4. Each phase switching switch assembly 4 includes a drive cross arm 4.1, a mounting bracket 4.2, and a vacuum interrupter 4.3. Each phase has two vacuum interrupters 4.3; the servo motor 1.1 is connected to the gearbox 1.2 and mounted on the gearbox 1.2; the drive cam disc 1.3, transmission gear 1.4, and drive lever wheel 1.5 are all mounted on the bottom of the gearbox 1.2; the slot bar 2.1 is mounted on the linkage mechanism 2.2; the linkage mechanism 2.2 is mounted on the insulated mounting main board 6; the selector switch assembly 3, the changeover switch assembly 4, and the transition element 5 are all mounted on the insulated mounting main board 6; the linkage mechanism 2.2 includes... It includes a linear guide rail 2.2.1, a connecting screw 2.2.2, and three sliders 2.2.3. The groove 2.1 is fixed on the connecting screw 2.2.2. The linear slide rail 2.2.1.1 and the connecting screw 2.2.2 on the linear guide rail 2.2.1 are both fixedly connected to the sliders 2.2.3. The linear guide rail 2.2.1 is fixedly mounted on the insulating mounting main board 6 through two linear guide blocks 2.2.1.2 on it. The sliders 2.2.3 drive the moving contact assembly 3.2 to move linearly.

[0039] Each phase's moving contact assembly 3.2 includes two moving contacts 3.2.1 and a moving contact seat 3.2.2. The moving contacts 3.2.1 are mounted on the moving contact seat 3.2.2, which is mounted on a guide rod 3.1. The moving contact seat 3.2.2 moves linearly on the guide rod 3.1, which is fixedly mounted on an insulating bracket 3.4. The stationary contact assembly 3.3 includes multiple stationary contacts 3.3.1 arranged in a straight line and a stationary contact integrated seat 3.3.2. The multiple stationary contacts 3.3.1 are mounted and fixedly mounted on the stationary contact integrated seat 3.3.2, which is fixedly connected to the insulating bracket 3.4 and the insulating mounting plate 6 via fixing studs. The stationary contact integrated base 3.3.2 has protrusions 3.3.2.1 on its upper and lower sides. The protrusions 3.3.2.1 are located outside the gap between the stationary contacts 3.3.1. The plane of the protrusion 3.3.2.1 on the upper side of the stationary contact integrated base 3.3.2 is higher than the upper plane of the stationary contact 3.3.1, and the plane of the protrusion 3.3.2.1 on the lower side of the stationary contact integrated base 3.3.2 is lower than the lower plane of the stationary contact 3.3.1.

[0040] A three-phase tripping arm 4.1.1 is installed on the drive arm 4.1. The moving contacts of the two vacuum interrupters 4.3 of each phase are fixedly connected to the drive arm 4.1 via the two tripping arms 4.1.1. A three-phase interrupter mounting base 4.2.1 is installed on the mounting bracket 4.2. The stationary contacts of the two vacuum interrupters 4.3 of each phase are fixedly mounted on the mounting bracket 4.2 via the two interrupter mounting bases 4.2.1. There are two drive arms 4.1 and two mounting brackets 4.2. The upper and lower drive arms 4.1 are connected and fixed by two connecting blocks 4.1.2. The drive shaft 2.3 is connected to one of the connecting blocks 4.1.2, driving the connecting block 4.1.2 to move laterally, which in turn drives the drive arm 4.1 to move laterally. The upper and lower drive arms 4.1 move between the two mounting brackets 4.2. The mounting brackets 4.2 guide the drive arms 4.1.

[0041] Servo motor 1.1 drives gearbox 1.2, which in turn rotates drive cam disc 1.3. Gears are mounted on drive cam disc 1.3 and mesh with transmission gear 1.4. The rotation of drive cam disc 1.3 drives transmission gear 1.4, which in turn drives drive lever wheel 1.5. Drive cam disc 1.3, via transmission shaft 2.3, drives drive cross arm 4.1, which in turn drives opening arm 4.1.1, which in turn drives vacuum interrupter 4.3, thus completing the gear shift. Drive lever wheel 1.5 is equipped with lever 1.5.1 and limit block 1.5. 2. The drive lever wheel 1.5 enters the groove between the teeth 2.1.1 on the groove bar 2.1 through the lever 1.5.1, driving the groove bar 2.1 to move linearly. This transforms the circular rotation of the drive lever wheel 1.5 into the linear motion of the groove bar 2.1. The groove bar 2.1 drives the linkage mechanism 2.2, which in turn drives the moving contact assembly 3.2 to select the corresponding stationary contact 3.3.1 in the stationary contact assembly 3.3 for electrical connection, thus completing the gear selection. After gear selection, the limiting block 1.5.2 on the drive lever wheel 1.5 meshes with a tooth on the groove bar 2.1 to perform positioning and limiting.

[0042] See Figure 8 , Figure 9 This utility model discloses a miniaturized on-load tap changer, explaining two different voltage regulation and wiring principles. By adjusting the electrical connection methods and operating timing of the components in the switch structure, two different switching principles can be achieved, applicable to different situations. See also Figure 8 This is a schematic diagram of a conventional linear on-load tap changer; see [link / reference]. Figure 9 Adopting the principle of bridging, it can be directly used to transform off-excitation distribution transformers into on-load tap-changing distribution transformers, that is, the miniaturized on-load tap-changing switch of this utility model can be directly replaced with the off-excitation on-load tap-changing switch.

[0043] See Figure 8 This refers to the timing principle of on-load tap changer switching based on the linear voltage regulation principle: A and D2 are the main circuits, and B, R, and D1 are the transition circuits. The timing sequence for switching from the N+1 tap of the voltage regulating winding to the N tap is as follows:

[0044] Step 1: Both moving contacts A and B are connected to tap N+1, and both vacuum interrupters D1 and D2 are connected. Current flows from tap N+1 through moving contact A and vacuum interrupter D2.

[0045] Step 2: Vacuum interrupter D2 is disconnected, moving contact A is disconnected from tap N+1, while moving contact B remains connected to tap N+1. Current flows from tap N+1 through moving contact B, transition element 6, and vacuum interrupter D1.

[0046] Step 3: The moving contact B remains connected to the N+1 tap, and the moving contact A changes from having no current at the N+1 tap to the N tap. The current flows from the N+1 tap through the moving contact B, the transition element 6, and the arc-extinguishing chamber D1.

[0047] Step 4: The moving contact B remains connected to the N+1 tap, the vacuum interrupter D2 is closed, the moving contact A is connected to the N tap, and the current flows from the N+1 tap through the moving contact B, the transition element 6, and the vacuum interrupter D1, and from the N tap through the moving contact A and the vacuum interrupter D2. At this time, a brief circulating current is generated between the N+1 tap and the N tap.

[0048] Step 5: Vacuum interrupter D1 is disconnected, moving contact B is disconnected from tap N+1, moving contact A remains connected to tap N, and current flows from tap N through moving contact A and vacuum interrupter D2.

[0049] Step 6: Moving contact A remains connected to tap N, while moving contact B switches from tap N+1 (no current) to tap N. Current flows from tap N through moving contact A and vacuum interrupter D2.

[0050] Step 7: Moving contact A remains connected to the N tap, vacuum interrupter D1 is connected, moving contact B is connected to the N tap, and current flows from the N tap through moving contact A and vacuum interrupter D2.

[0051] See Figure 9 This is a schematic diagram of the operating timing of an on-load tap changer using the bridging principle. A1, D1, and A2 are the main circuits, and R and D2 are the transition circuits. The diagram illustrates the timing of the tap changer switching from one tap to another.

[0052] Step 1: Vacuum interrupter D1 is connected, moving contact A1 is connected to tap 2, moving contact A2 is connected to tap 1, vacuum interrupter D2 is disconnected, and current flows through voltage regulating windings L4 and L3, tap 2, moving contact A1, vacuum interrupter D1, moving contact A2, tap 1, and then through voltage regulating windings L2 and L1 and high voltage winding.

[0053] Step 2: Vacuum interrupter D1 is connected, moving contact A1 is connected to tap 2, moving contact A2 is connected to tap 1, and vacuum interrupter D2 is connected. Current flows through voltage regulating windings L4 and L3, tap 2, moving contact A1, vacuum interrupter D1, moving contact A2, and tap 1, then through voltage regulating windings L2 and L1 and the high-voltage winding. Current flows through voltage regulating windings L4 and L3, tap 2, resistor R, and vacuum interrupter D2, then through the high-voltage winding. At this time, a brief circulating current will be generated between the taps.

[0054] Step 3: Vacuum interrupter D1 is disconnected, moving contact A1 is disconnected from tap 2, moving contact A2 is disconnected from tap 1, vacuum interrupter D2 remains connected, and current flows through voltage regulating windings L4 and L3, through resistor R, vacuum interrupter D2, and then through high voltage winding.

[0055] Step 4: Vacuum interrupter D1 remains open. Moving contacts A1 and A2 perform position selection. Moving contact A1 moves to connect with tap 3, and moving contact A2 moves to connect with tap 2. Vacuum interrupter D2 remains closed. Current flows through voltage regulating windings L4 and L3, through resistor R, through vacuum interrupter D2, and then through high-voltage winding.

[0056] Step 5: Vacuum interrupter D1 is connected, moving contact A1 is connected to tap 3, moving contact A2 is connected to tap 2, and vacuum interrupter D2 remains connected. Current flows through voltage regulating windings L4 and L3, through moving contact A2, vacuum interrupter D1, and moving contact A1, then through voltage regulating winding L1 and high voltage winding. Current also flows through voltage regulating windings L4 and L3, through tap 2, resistor R, vacuum interrupter D2, and then through high voltage winding. At this time, a brief circulating current will be generated between the taps.

[0057] Step 6: Vacuum interrupter D1 is connected, moving contact A1 is connected to tap 3, moving contact A2 is connected to tap 2, vacuum interrupter D2 is disconnected, and current flows through voltage regulating windings L4 and L3, through moving contact A2, vacuum interrupter D1, moving contact A1, and then through voltage regulating winding L1 and high voltage winding.

[0058] The above descriptions only illustrate two different structures and voltage regulation principles using a 5-position on-load tap changer as an example. Other positions or other conventional on-load tap changer principles, such as 7-position, 9-position, or coarse / fine adjustment, forward / reverse adjustment principles, can be modified by those skilled in the art based on this invention, and all modifications fall within the scope of protection of this invention. This invention describes the position switching process of the on-load tap changer. The selection switch assembly moves or selects the corresponding contacts in a no-current state, which is well-known to those skilled in the art and will not be described further. Throughout the entire selection and switching process, the arc is generated only in the vacuum interrupter chamber, preventing contamination of the transformer oil and eliminating the need for regular oil filtration or filter replacement, thus significantly reducing operating and maintenance costs.

[0059] This invention, in designing a dedicated on-load tap changer for distribution transformers, focuses on miniaturization, maintenance-free operation, and a lifespan equivalent to the transformer's design life. It employs a servo motor with flexible drive to operate its mechanical components, significantly reducing the impact on related parts (switching switch assembly, selection switch assembly) during the on-load tap changer's drive transmission, thus improving the actual service life and reliability of each component. The switching switch assembly incorporates two vacuum interrupters; during tap change, both interrupters operate only once. This contrasts with other designs using only one vacuum interrupter, which require two operations per tap change and more complex mechanical mechanisms. Furthermore, by using the same type of vacuum interrupter, this invention doubles the lifespan compared to designs using only one vacuum interrupter. The present invention offers several advantages: High switch reliability; the vacuum interrupter in the switching assembly adopts a horizontal structure, with the three-phase vacuum interrupters arranged in a straight line, significantly reducing the overall height of the on-load tap changer; the drive cam disc can be designed with different cam and slot structures to meet different principle or timing requirements; simultaneously, both the selection switch assembly and the switching assembly of the on-load tap changer are mounted on the same insulating mounting plate. Compared to switches mounted on different mounting plates, the structure of the present invention is simpler and more compact, reducing the length and width of the switch, resulting in a miniaturized overall design. By adopting the aforementioned solutions, the present invention achieves miniaturization, maintenance-free operation, and high reliability of the on-load tap changer, making it suitable for a large number of distribution transformers. Furthermore, the present invention provides a miniaturized on-load tap changer that can be directly used for the retrofitting of off-excitation distribution transformers, directly replacing off-excitation switches and significantly saving costs compared to purchasing new on-load tap changer distribution transformers. Improvements can be made within the technical field based on the preferred embodiments of the present invention, which fall within the protection scope of the present invention.

[0060] The above description is only a preferred embodiment of the present utility model. It should be noted that for those skilled in the art, several changes and improvements can be made without departing from the technical principles of the present utility model, and these changes and improvements should also be considered within the protection scope of the present utility model.

Claims

1. A miniaturized on-load tap changer, characterized in that The application relates to a transmission mechanism for a transmission switch, which comprises a driving mechanism assembly, a transmission mechanism assembly, a selection switch assembly, a switching switch assembly, a transition element and an insulating installation main plate, wherein the selection switch assembly, the switching switch assembly and the transition element each have three phases. The driving mechanism assembly comprises a servo motor, a gearbox, a driving cam disc, a transmission gear and a driving lever wheel. The transmission mechanism assembly comprises a groove strip, a linkage mechanism and a transmission shaft. The selection switch assembly of each phase comprises a guide rod, a moving contact assembly, a static contact assembly and an insulating support. The switching switch assembly of three phases comprises a driving cross arm, an installation support and a vacuum arc-extinguishing chamber, wherein the vacuum arc-extinguishing chambers of the three phases are driven to act under the driving of the driving cross arm. The servo motor is connected with the gearbox and is installed on the gearbox. The driving cam disc, the transmission gear and the driving lever wheel are all installed on the bottom of the gearbox. The groove strip is installed on the linkage mechanism, and the linkage mechanism is installed on the insulating installation main plate. The selection switch assembly of three phases, the switching switch assembly and the transition element are all installed on the insulating installation main plate. The servo motor drives the gearbox to act, the gearbox drives the driving cam disc to rotate, the driving cam disc drives the transmission gear to act, the transmission gear drives the driving lever wheel to act, the driving cam disc drives the driving cross arm to act through the transmission shaft, the driving cross arm drives the vacuum arc-extinguishing chambers of three phases to act, and the switching of gears is completed; the driving lever wheel drives the groove strip to act, the groove strip drives the linkage mechanism to act, the linkage mechanism drives the moving contact assembly to act, and then the static contact in the corresponding static contact assembly is selected to be electrically connected, and the selection of gears is completed.

2. A compact on-load tap changer according to claim 1, characterized in that A gear is arranged on the driving cam disc, the gear is engaged with the transmission gear, and the rotation of the gear drives the rotation of the transmission gear; different cams and grooves are arranged in the driving cam disc, and the transmission shaft drives the vacuum arc-extinguishing chambers to act in sequence along with the movement of the grooves.

3. The compact on-load tap changer according to claim 1, characterized in that A lever and a limiting block are arranged on the driving lever wheel, the driving lever wheel drives the groove strip to move linearly through the lever, the rotation of the driving lever wheel is changed into the linear action of the groove strip, and the limiting block is engaged with a certain groove tooth on the groove strip to limit the position when the selection of gears is completed.

4. The compact on-load tap changer of claim 1, wherein, The driving cam disc and the driving lever wheel rotate synchronously, drive the switching switch assembly and the selection switch assembly to act in sequence, and the conversion of the voltage regulating gears is completed.

5. The compact on-load tap changer of claim 1, wherein, The linkage mechanism comprises a linear guide rail, a linkage screw and three sliding blocks, the groove strip is fixed on the linkage screw, the linear sliding rail on the linear guide rail and the linkage screw are fixedly connected with the sliding blocks, the linear guide rail is fixedly installed on the insulating installation main plate through two linear sliding guide blocks thereon, and the sliding blocks drive the moving contact assembly to move linearly.

6. The compact on-load tap changer of claim 1, wherein, The moving contact assembly comprises two moving contacts, a moving contact seat, the moving contact is installed on the moving contact seat, the moving contact seat is installed on the guide rod, the moving contact seat moves linearly on the guide rod, and the guide rod is fixedly installed on the insulating support; the static contact assembly comprises a plurality of static contacts arranged in a straight line and a static contact integrated seat, the plurality of static contacts are fixedly installed on the static contact integrated seat, and the static contact integrated seat is fixedly connected with the insulating support and the insulating installation main plate through fixing studs.

7. A compact on-load tap changer according to claim 6, characterized in that The upper and lower sides of the static contact integrated seat are provided with protrusions, the protrusions are located outside the gaps between the static contacts, the plane of the protrusion on the upper side of the static contact integrated seat is higher than the upper plane of the static contact, and the plane of the protrusion on the lower side of the static contact integrated seat is lower than the lower plane of the static contact.

8. The compact on-load tap changer of claim 1, wherein, The three-phase vacuum arc-extinguishing chambers are arranged in a straight line, three-phase opening arms are arranged on the driving cross arms, the moving contact parts of the vacuum arc-extinguishing chambers are fixedly connected with the driving cross arms through the opening arms, three-phase arc-extinguishing chamber installation seats are arranged on the installation supports, and the static contact parts of the vacuum arc-extinguishing chambers are fixedly installed on the installation supports through the arc-extinguishing chamber installation seats.

9. The compact load regulation switch of claim 1, wherein, The driving cross arms and the installation supports are both two, the two driving cross arms are fixedly connected through two connecting blocks, the transmission shaft is connected with one of the connecting blocks, the connecting block is driven to move transversely, and the driving cross arms are driven to move transversely; the two driving cross arms move between the two installation supports, and the installation supports have a guiding effect on the driving cross arms.

10. A load-regulated distribution transformer, characterized in that The on-load voltage regulating distribution transformer with the miniaturized on-load voltage regulating switch of any of the preceding claims comprises a voltage regulating main circuit and a transition circuit, the voltage regulating main circuit is in a conducting state and the transition circuit is in a disconnected state when the on-load voltage regulating distribution transformer is in normal operation; when the voltage regulating tap position is converted, the switching switch assembly has a time sequence action, so that the transition circuit is first conducted and the voltage regulating main circuit is disconnected, two moving contacts in the moving contact assembly in the selection switch assembly act to select the corresponding fixed contacts in the fixed contact assembly to complete the selection of the voltage regulating tap position, the switching switch assembly has a time sequence action, so that the voltage regulating main circuit is conducted and the transition circuit is disconnected to complete the conversion of the tap position; when the cross connection principle is used, the transition circuit is fixed at a certain tap position of the transformer voltage regulating winding, two moving contacts in the moving contact assembly of the miniaturized on-load voltage regulating switch in the voltage regulating main circuit are respectively electrically connected to two corresponding fixed contacts in the fixed contact assembly to be conducted, and two fixed contacts are respectively electrically connected to two corresponding tap taps of the transformer high voltage coil voltage regulating winding; when the linear voltage regulating principle is used, the transition circuit gradually changes with the change of the voltage regulating main circuit, two moving contacts in the moving contact assembly of the miniaturized on-load voltage regulating switch in the voltage regulating main circuit are electrically connected to a corresponding fixed contact in the fixed contact assembly to be conducted, and the fixed contact is electrically connected to a corresponding tap tap of the transformer high voltage coil voltage regulating winding.

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