On-load voltage regulating switch for distribution transformer and on-load voltage regulating distribution transformer

Abstract

The patent of the present invention discloses a special on-load voltage regulating switch for distribution transformer and an on-load voltage regulating distribution transformer. The switch includes a mounting main board, an insulating back plate, a driving mechanism component, a selection switch component, a switching switch component, and a transition element. The driving mechanism component includes a stepping motor, a gearbox, a bevel gear, a driving gear, and a square shaft. The rotational motion of the stepping motor is transmitted to the driving gear by means of the gearbox and the bevel gear. The driving gear drives the square shaft to rotate, and then drives the selection switch component and the switching switch component to move, completing the conversion of the voltage regulating gear. The on-load voltage regulating switch is miniaturized, and is installed in the distribution transformer without changing its conventional shape and volume. Frequent voltage adjustment of the distribution transformer under load is realized, the power supply voltage is stabilized, the loss is reduced, and a wide range of multi-gears and refined voltage regulation are realized. At the same time, the life cycle of the switch is equal to the life cycle of the distribution transformer body, and no maintenance is required during its life cycle, which improves the reliability of the on-load voltage regulation of the distribution transformer.

Description

Technical Field

[0001] The device relates to the technical field of electric power products, and in particular to an on-load voltage regulating switch dedicated to a distribution transformer and an on-load voltage regulating distribution transformer. Background Art

[0002] The distribution transformer is the last transformer of the power supply network. It is used in various fields of national economy and people's livelihood, and is spread all over every corner of urban and rural areas. The number is huge. The current distribution transformers are all off-excitation voltage regulation mode. When regulating the voltage, it is necessary to cut off the power supply first, and then manually adjust the off-excitation voltage regulation switch. After the adjustment is completed, the power supply can be restored. Since the voltage regulation requires power outage and cannot be achieved in time, the distribution transformer in the actual power supply network is equivalent to no voltage regulation measures, resulting in low power supply voltage qualification rate, poor stability, abnormal operation of electrical equipment, and increased losses of the distribution transformer itself and electrical equipment. With the continuous improvement and development of social economy and power grid, the requirements for voltage quality will become higher and higher, and therefore the reliability requirements for on-load voltage regulation distribution transformers will become higher and higher. In order to meet the needs of different occasions, the demand for the number of voltage regulation gears and wide voltage regulation range of on-load voltage regulation distribution transformers will continue to increase.

[0003] In recent years, there have been cases where the on-load voltage regulator of the main transformer has been applied to the distribution transformer to achieve on-load voltage regulation. However, the on-load voltage regulator of the main transformer is large in size and requires regular maintenance, which cannot meet the reliability requirements of the distribution transformer and is not suitable for a large number of distribution transformers. There are also on-load voltage regulators on the market that use spring energy storage and permanent magnet and electromagnetic drive methods for distribution transformers. Although they also use vacuum arc extinguishing, this type of drive method has a large impact force during the drive transmission, which affects the service life of the on-load voltage regulator related components, so that its life cycle cannot meet the design life cycle of the distribution transformer, and is not suitable for use in a large number of distribution transformers.

[0004] DE19743864C1 describes an on-load tap changer using a reactor transition method, in which the selection switch component and the switching switch component are both arranged on the same phase plate. The structural design is complex, and the overall switch occupies a large space. In addition, the use of reactors for on-load voltage regulation transition greatly increases the cost of the on-load voltage regulation switch, and is not suitable for a large number of distribution transformers.

[0005] MR of Germany has applied for the following Chinese invention patents in China: 1. Application number 201780005054.9, invention name "On-load tap changer"; 2. Application number 201780007088.1, invention name "On-load tap changer, adjustable transformer with on-load tap changer and method for switching on-load tap changer". The above two invention patents only describe the structure and operation of the selection component and switching component of the on-load tap changer, but do not elaborate on its driving transmission mechanism. The design life of the distribution transformer is at least 30 years, and it has higher requirements for the reliability of the on-load voltage regulator. The function realized by the above two invention patents is that the transformer performs voltage regulation without interruption, but its reliability is not elaborated. The driving part of the on-load voltage-regulating switch is also one of its core components, which is not elaborated in the invention. If the driving mechanism adopts spring energy storage or permanent magnet drive, the impact force during the switching process is relatively large, which will greatly reduce the performance of the on-load voltage-regulating switch and affect the service life of the on-load tap changer; at the same time, each phase switching component of the switch adopts a single vacuum arc chamber and its mechanical mechanism to cooperate with the switching. When it switches from N taps to N+1 taps, the vacuum arc chamber needs to be opened and closed twice, and the current is turned on and off in the vacuum arc chamber. The requirements for the contacts of the vacuum arc chamber are relatively high. Compared with the vacuum arc chamber that is only connected and disconnected once during the gear shifting process, its reliability is low. The invention patent "On-load tap changer, adjustable transformer with on-load tap changer and method for switching on-load tap changer" is based on the invention patent "On-load tap changer", with a preselector set and a set of Maltese wheels added to increase the number of voltage regulation gears. Its structural design is relatively complex and increases the length of the switch. It can be seen from its drawings that two rods or bars are used to fix the various components, both of which are cylindrical, which increases the overall height of the switch. It can be seen from its description and drawings that its structural design does not invent a miniaturized on-load tap changer suitable for distribution transformers. The size of the on-load tap changer will affect the size, production cost and installation space of the distribution transformer, and the distribution transformer requires a miniaturized, highly reliable on-load tap changer. Summary of the invention

[0006] The purpose of the present invention is to provide an on-load voltage regulating switch dedicated to a distribution transformer, so as to solve the problem in the prior art that the on-load voltage regulating switch needs regular maintenance, and at the same time solve the problem in the prior art that the on-load voltage regulating switch is large in size and inconvenient to install, thereby realizing the miniaturization of the on-load voltage regulating switch, so that it can be installed without changing the size and shape of the conventional distribution transformer, realizing the long life and maintenance-free characteristics of the on-load voltage regulating switch, and making its life cycle equal to the life of the distribution transformer body.

[0007] In order to achieve the above object, the present invention adopts the following technical scheme:

[0008] A special on-load tap-changing switch for distribution transformers, characterized in that it comprises a mounting main board, an insulating back plate, a drive mechanism assembly, a selection switch assembly, a switching switch assembly, and a transition element;

[0009] The driving mechanism assembly includes a stepping motor, a gearbox, a bevel gear, a driving gear, and a square shaft;

[0010] The gearbox is provided with a position sensor to directly collect and transmit the gear position signal during the driving transmission process;

[0011] The selection switch assembly, the switching switch assembly, and the transition element each have three groups, which respectively complete the selection and switching of the three-phase voltage regulation gears;

[0012] Each group of the switching switch assembly includes a switching switch mainboard, two vacuum interrupters, and two cams;

[0013] Each set of the selection switch assembly includes a selection switch main board, two sets of groove wheel mechanisms, a fine selection contact assembly, a rough selection drive tooth, an incomplete gear mechanism, and a rough selection contact assembly, and the groove wheel mechanism includes a dial and a groove wheel;

[0014] The stepper motor is mounted on the gearbox, and the gearbox, the selection switch mainboard, and the switching switch mainboard are fixed on the mounting mainboard;

[0015] The insulating back plate is fixedly connected to one end of the selection switch main board and the switching switch main board;

[0016] The square shaft runs through the selection switch mainboard and the switching switch mainboard;

[0017] The driving gear, the cam and the dial are sleeved on the square shaft;

[0018] The two vacuum interrupters are fixedly mounted on one side of the switch mainboard, and the transition element is fixedly mounted on the other side of the switch mainboard;

[0019] The two groups of the grooved wheel mechanisms on each group of the selection switch assembly are respectively installed on both sides of the selection switch main board, the rough selection drive teeth are installed and fixed on the grooved wheel of one of the grooved wheel mechanisms, the incomplete gear mechanism is installed and fixed on one side of the selection switch main board, and the rough selection contact assembly is fixed on one side of the selection switch main board through a fixing column;

[0020] The coarse selection drive teeth, the incomplete gear mechanism, and the coarse selection contact assembly are on the same side of the selection switch mainboard;

[0021] The rotational motion of the stepper motor is transmitted to the driving gear by means of the gearbox and the bevel gear, and the driving gear drives the square shaft to rotate, and then drives the cam and the dial to rotate, and the cam drives the on and off of the vacuum interrupter to complete the energized switching of the voltage regulating gear; the dial drives the groove wheel to move, and the groove wheel drives the fine selection contact assembly and the coarse selection drive teeth to move, and perform the non-energized selection of the voltage regulating gear; when the corresponding voltage regulating gear is converted, the coarse selection drive teeth drive the incomplete gear mechanism to move, and then drive the coarse selection contact assembly to move, and together with the fine selection contact assembly, complete the non-energized selection of the voltage regulating gear and complete the voltage adjustment.

[0022] According to a preferred embodiment of the present invention, the voltage regulating gear position is controlled and positioned by the stepping motor.

[0023] According to a preferred embodiment of the present invention, the gearbox includes a case body, a case cover, an electronic circuit board, a position sensor, and a gear set. The position sensor transmits the movement information of the gear set to the electronic circuit board, and the electronic circuit board performs analysis and processing to output the gear position of the on-load voltage regulating switch.

[0024] According to a preferred embodiment of the present invention, the two cams in the switching switch assembly respectively control the switching of the two vacuum interrupters.

[0025] According to a preferred embodiment of the present invention, the fine selection contact assembly includes two moving contacts and a static contact group, the two moving contacts are respectively fixedly mounted on the two groove wheels in the selection switch assembly, and the static contacts in the static contact group are fixedly passed through the selection switch mainboard, and the number of the static contacts is the same as the number of teeth on the groove wheel; when selecting a gear, the groove wheel drives the moving contact to rotate and selects the corresponding static contact in the static contact group.

[0026] According to a preferred embodiment of the present invention, the rough selection contact assembly includes a moving contact, two stationary contacts, and a contact fixing plate, and the moving contact and the two stationary contacts are all mounted on the contact fixing plate. When the voltage regulating gear is switched, when the rough selection drive tooth moves to engage with the corresponding gear on the incomplete gear mechanism, the rough selection drive tooth drives the incomplete gear mechanism to move, and the incomplete gear mechanism drives the moving contact in the rough selection contact assembly to select the corresponding stationary contact in the rough selection contact assembly without current.

[0027] An on-load voltage-regulating distribution transformer, characterized in that it is an on-load voltage-regulating distribution transformer using any of the above-mentioned on-load voltage-regulating switches dedicated to distribution transformers.

[0028] Compared with the prior art, the beneficial effect of the present invention is that a special on-load voltage regulating switch for distribution transformer is invented, which is installed in the body of the distribution transformer without changing the shape and volume of the conventional distribution transformer; it realizes frequent voltage adjustment of the distribution transformer under load, stabilizes the power supply voltage, and reduces losses. The present invention also realizes wide-range voltage regulation of the distribution transformer, which can achieve 17 levels of ±8×2.5% wide-range voltage regulation, and at the same time realizes more than 600,000 trouble-free and maintenance-free continuous voltage regulation actions, which can be maintenance-free within the life cycle of the distribution transformer, thereby improving the reliability of on-load voltage regulation of the distribution transformer. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a schematic diagram A of the overall structure of the on-load voltage regulating switch dedicated to the distribution transformer of the present invention;

[0030] Figure 2 This is a schematic diagram B of the overall structure of the on-load tap-changing switch dedicated to the distribution transformer of the present invention;

[0031] Figure 3 It is a schematic diagram of the internal mechanism of the gearbox of the on-load tap-changing switch dedicated to the distribution transformer of the present invention;

[0032] Figure 4 It is a schematic diagram of the switch assembly of the on-load tap-changing switch dedicated to the distribution transformer of the present invention (one side of the switch mainboard);

[0033] Figure 5 It is a schematic diagram of the other side of the switching switch mainboard of the on-load tap-changing switch dedicated to the distribution transformer of the present invention;

[0034] Figure 6 It is an overall schematic diagram of the selector switch assembly of the on-load tap-changing switch dedicated to the distribution transformer of the present invention;

[0035] Figure 7 Schematic diagram A of the disassembly of the selector switch assembly of the on-load tap-changing switch dedicated to the distribution transformer of the present invention;

[0036] Figure 8 Schematic diagram B of the disassembly of the selector switch assembly of the on-load tap-changing switch dedicated to the distribution transformer of the present invention;

[0037] Fig. 9 It is a structural schematic diagram of a selector switch assembly of an on-load tap-changing switch dedicated to a distribution transformer of the present invention without a groove wheel on one side;

[0038] Fig.10 The present invention is a schematic diagram of the timing of fine-selection of the gear selection and switching of the on-load voltage regulating switch specially used for the distribution transformer. DETAILED DESCRIPTION

[0039] The present invention is further described below in conjunction with the accompanying drawings. The embodiments described below are only used to more clearly illustrate the technical solution of the present invention. They are selected embodiments of the present invention, not all embodiments, and cannot be used to limit the scope of protection of the present invention. All other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0040] Figures 1 to 9 This is a schematic diagram of a preferred on-load voltage regulating switch for distribution transformers that can achieve 17 voltage regulating gears according to the present invention, see Figure 1 , Figure 2 As shown, a special on-load tap-changing switch for distribution transformers includes a mounting main board 1, an insulating back plate 2, a drive mechanism assembly 3, a selection switch assembly 4, a switching switch assembly 5, and a transition element 6; the drive mechanism assembly includes a stepping motor 31, a gearbox 32, a bevel gear 33, a driving gear 34, and a square shaft 35.

[0041] See also Figure 3 As shown, the gearbox 32 includes a box body 321, a box cover 322, an electronic circuit board 323, a position sensor 324, and a gear set 325;

[0042] There are three groups of selection switch components 4, switching switch components 5, and transition elements 6, respectively, to complete the selection and switching of three-phase voltage regulation gears;

[0043] See also Figure 4 , Figure 5 As shown, each group of switching switch components 5 includes a switching switch main board 51, two vacuum arc extinguishing chambers 52, 53, and two cams 54, 55; the vacuum arc extinguishing chambers 52, 53 are fixedly mounted on one side of the switching switch main board 51 by relevant fixing devices, the two cams 54, 55 are sleeved on the square shaft 35, and the transition element 6 is fixedly mounted on the other side of the switching switch main board 51. The transition element 6 of the present invention is preferably a transition resistor.

[0044] See also Figure 6 , Figure 7 , Figure 8 , Fig. 9 As shown, each group of selection switch components 4 includes a selection switch main board 41, two groups of groove wheel mechanisms 42, 43, a fine selection contact assembly 44, a rough selection drive tooth 45, an incomplete gear mechanism 46, and a rough selection contact assembly 47. The groove wheel mechanisms 42, 43 include dials 421, 431, groove wheels 422, 432; the fine selection contact assembly 44 includes two moving contacts 441, 442, and a stationary contact group 443. The number of stationary contacts in the stationary contact group 443 is the same as the number of teeth of the groove wheel 422 or the groove wheel 432. Fig. 9The static contact group shown includes 9 static contacts; the rough selection contact assembly 47 includes a moving contact 471, two static contacts 472, 473, and a contact fixing plate 474;

[0045] Two groups of groove wheel mechanisms 42 and 43 are respectively installed on both sides of the selection switch main board 41, the moving contacts 441 and 442 are respectively fixedly installed on the groove wheels 422 and 432, the static contacts in the static contact group 443 are fixedly passed through the selection switch main board 41, the coarse selection drive teeth 45 are installed and fixed on the groove wheel 422 of one of the groove wheel mechanisms 42, the incomplete gear mechanism 46 is installed and fixed on one side of the selection switch main board 41, and the coarse selection contact assembly 47 is fixed on one side of the selection switch main board 41 through a fixing column; the coarse selection drive teeth 45, the incomplete gear mechanism 46, and the coarse selection contact assembly 47 are on the same side of the selection switch main board 41.

[0046] The stepper motor 31 is mounted on the gearbox 32. The gearbox 32, the selection switch main board 41, and the switching switch main board 51 are fixed on the mounting main board 1. The insulating back plate 2 is fixedly connected to one end of the selection switch main board 41 and the switching switch main board 51. The square shaft 35 runs through the selection switch main board 41 and the switching switch main board 51. The driving gear 34, the cams 54, 55, and the dials 421, 431 are mounted on the square shaft 35.

[0047] The rotation of the stepper motor 31 is transmitted to the driving gear 34 by means of the gearbox 32 and the bevel gear 33. The driving gear 34 drives the square shaft 35 to rotate, and then drives the cams 54, 55 and the dials 421, 431 to rotate. The cams 54, 55 push the vacuum interrupter 52, 53 to be turned on and off through the driving rod, completing the live switching of the voltage regulating gear; the dials 421, 431 push the groove wheels 422, 432 to move, and the groove wheels 422, 432 drive the moving contacts 441, 442 in the fine selection contact assembly 44. 442, the coarse selection drive tooth 45 moves, and the moving contacts 441 and 442 select the corresponding static contacts in the static contact group 443. When the corresponding gear is switched, the coarse selection drive tooth 45 moves to engage with the corresponding gear on the incomplete gear mechanism 46, and the coarse selection drive tooth 45 drives the incomplete gear mechanism 46 to move, and then drives the moving contact 471 in the coarse selection contact assembly 47 to select the corresponding static contact 472 or static contact 473, completing the non-energized selection of the voltage regulation gear and completing the voltage adjustment.

[0048] See also Fig.10 These are seven steps of a fine-selection gear selection switching process of an on-load voltage regulating switch dedicated to a distribution transformer of the present invention. In the figure, N and N+1 represent two adjacent coil taps of the voltage regulating winding, A and B represent two moving contacts 441 and 442 in the fine-selection contact assembly 44 in the selection switch assembly 4, R represents a transition element 6, and D1 and D2 represent two vacuum interrupters 52 and 53 in the switching switch assembly 5.

[0049] The timing of switching from the N+1 tap of the voltage regulating winding to the N tap is:

[0050] Step 1: The moving contacts A and B are connected to the N+1 tap, and the vacuum interrupters D1 and D2 are connected. The current flows from the N+1 tap through the moving contact A and the vacuum interrupter D2.

[0051] Step 2: The vacuum interrupter D2 is disconnected, the moving contact A is disconnected from the N+1 tap, and the moving contact B is still connected to the N+1 tap. The current flows from the N+1 tap through the moving contact B, the transition element 6, and the vacuum interrupter D1.

[0052] Step 3: The moving contact B is still connected to the N+1 tap, and the moving contact A is switched from the N+1 tap with no current 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.

[0053] Step 4: The moving contact B is still connected to the N+1 tap, the vacuum interrupter D2 is closed, the moving contact A is connected to the N tap, the current flows from the N+1 tap through the moving contact B, the transition element 6, and the vacuum interrupter D1, and the current flows from the N tap through the moving contact A and the vacuum interrupter D2. At this time, a short circulating current is generated between the N+1 tap and the N tap.

[0054] Step 5: The vacuum interrupter D1 is disconnected, the moving contact B is disconnected from the N+1 tap, the moving contact A is still connected to the N tap, and the current flows from the N tap through the moving contact A and the vacuum interrupter D2.

[0055] Step 6: The moving contact A is still connected to the N tap, and the moving contact B is switched from the N+1 tap with no current to the N tap. The current flows from the N tap through the moving contact A and the vacuum interrupter D2.

[0056] Step 7: The moving contact A is still connected to the N tap, the vacuum interrupter D1 is connected, the moving contact B is connected to the N tap, and the current flows from the N tap through the moving contact A and the vacuum interrupter D2.

[0057] The above is an explanation of the fine selection gear switching process of the on-load voltage regulating switch. The coarse selection part of the selection switch assembly is designed according to the conventional on-load voltage regulating method: coarse and fine voltage regulation principle, positive and negative voltage regulation principle, which is well known to technicians in this technical field and will not be explained again. In the above entire selection switching process, the arc is only generated in the vacuum interrupter chamber, which will not pollute the transformer oil, and there is no need to perform oil filter maintenance or replace the filter element regularly, which greatly saves the operation and maintenance costs.

[0058] When designing a dedicated on-load voltage regulator for a distribution transformer, the present invention is developed from the perspectives of miniaturization, maintenance-free, and a life span equivalent to the design life span of the transformer. The present invention uses a mounting mainboard with sufficient tolerance strength to fix and install various components to reduce the overall height of the on-load voltage regulator; at the same time, the rough selection and fine selection related components of the on-load voltage regulator are all arranged on the same selection switch mainboard. Compared with switches arranged on different mounting mainboards, the present invention has a simple and compact structural design, reduces the length of the switch, and the overall design of the switch is miniaturized. The flexible drive and precise positioning characteristics of the stepper motor 31 are used to drive and convert the voltage regulating gear and control the positioning, which greatly reduces the impact force on the relevant components (switching switch components, selection switch components) of the on-load voltage regulating switch during the driving and transmission process, and improves the actual service life and reliability of each component of the switch; the stepper motor 31 drives the gear set 325 in the gearbox 32 to rotate, and the position sensor 324 transmits the rotation information of the gear set 325 to the electronic circuit board 323, and the electronic circuit board 323 performs analysis and processing to directly output the gear position of the on-load voltage regulating switch. The position information of the voltage regulating gear is directly output in the gearbox 32, which omits the conventional high failure rate and unreliable The reliable position switch feedback device greatly improves the life and operational reliability of the on-load voltage regulator; two vacuum arc extinguishing chambers 52 and 53 are arranged in the switching switch assembly 5. When the voltage regulating gear is switched, the two vacuum arc extinguishing chambers 52 and 53 are only actuated once, compared with other vacuum arc extinguishing chambers that only have one vacuum arc extinguishing chamber, each gear switch needs to be actuated twice, and a more complex mechanical mechanism is required. If the same type of vacuum arc extinguishing chamber is selected, the life of the present invention is doubled compared with other vacuum arc extinguishing chambers that only have one vacuum arc extinguishing chamber, thereby improving the reliability of the switch; by selecting the above-mentioned scheme, the present invention realizes the miniaturization and high reliability of the on-load voltage regulator, and is suitable for a moderately large distribution transformer. In the technical field, improvements can be made according to the preferred embodiments of the present invention, for example, a motor mechanism such as a servo motor or a linear motor can be used instead of a stepper motor in combination with a control program for driving, which also belongs to the protection scope of the present invention.

[0059] There are mainly three types of voltage regulation methods for on-load voltage regulators: linear voltage regulation, positive and negative voltage regulation, and coarse and fine voltage regulation. The on-load voltage regulator dedicated to the distribution transformer of the present invention is applicable to all of them. Positive and negative voltage regulation and coarse and fine voltage regulation are only different in the winding method and wiring method of the voltage regulating winding. When the linear voltage regulation method is adopted, only the relevant components of the fine voltage regulation gear selection and switching of the present invention are adopted. In the preferred embodiment, the use of coarse and fine voltage regulation or positive and negative voltage regulation can achieve a wide voltage regulation of 17 gears ±8×2.5% of the on-load voltage regulator switch at most. If more gears of voltage regulation are still needed, the number of gears of the groove wheel and the corresponding static contacts can be increased, and the volume of the switch will also increase accordingly. Figures 1 to 9 This is a preferred implementation scheme of the present invention. The number of gears can be increased or decreased according to user needs, and the operating principle of the on-load voltage regulating switch remains unchanged.

[0060] The above is only a preferred embodiment of the present invention. It should be pointed out that for those skilled in the art, several changes and improvements can be made without departing from the technical principles of the present invention. These changes and improvements should also be regarded as the scope of protection of the present invention.

Claims

1. A special on-load voltage regulator for distribution transformers, which can achieve 17-speed wide range and fine voltage regulation, and is characterized by: Including installing the main board, insulating back plate, drive mechanism assembly, selector switch assembly, transfer switch assembly, and transition element; The driving mechanism assembly includes a stepping motor, a gearbox, a bevel gear, a driving gear, and a square shaft; The gearbox is provided with a position sensor to directly collect and transmit the gear position signal during the driving transmission process; The selection switch assembly, the switching switch assembly, and the transition element each have three groups, which respectively complete the selection and switching of the three-phase voltage regulation gears; Each group of the switching switch assembly includes a switching switch mainboard, two vacuum interrupters, and two cams; Each group of the selection switch assembly includes a selection switch main board, two groups of groove wheel mechanisms, a fine selection contact assembly, a rough selection driving tooth, an incomplete gear mechanism, and a rough selection contact assembly. The groove wheel mechanism includes a dial and a groove wheel. The rough selection contact assembly includes a moving contact, two stationary contacts, and a contact fixing plate. The moving contact and the two stationary contacts are both mounted on the contact fixing plate. The fine selection contact assembly includes two moving contacts and a stationary contact group. The two moving contacts are respectively fixedly mounted on the two groove wheels in the selection switch assembly. The stationary contacts in the stationary contact group are fixedly connected to the selection switch main board. The stepper motor is mounted on the gearbox, and the gearbox, the selection switch mainboard, and the switching switch mainboard are fixed on the mounting mainboard; The insulating back plate is fixedly connected to one end of the selection switch main board and the switching switch main board; The square shaft runs through the selection switch mainboard and the switching switch mainboard; The driving gear, the cam and the dial are sleeved on the square shaft; The two vacuum interrupters are fixedly mounted on one side of the switch mainboard, and the transition element is fixedly mounted on the other side of the switch mainboard; The two groups of the grooved wheel mechanisms on each group of the selection switch assembly are respectively installed on both sides of the selection switch main board, the rough selection drive teeth are installed and fixed on the grooved wheel of one of the grooved wheel mechanisms, the incomplete gear mechanism is installed and fixed on one side of the selection switch main board, and the rough selection contact assembly is fixed on one side of the selection switch main board through a fixing column; The coarse selection drive teeth, the incomplete gear mechanism, and the coarse selection contact assembly are on the same side of the selection switch mainboard; The rotational motion of the stepper motor is transmitted to the driving gear by means of the gearbox and the bevel gear, and the driving gear drives the square shaft to rotate, and then drives the cam and the dial to rotate, and the cam drives the on and off of the vacuum interrupter to complete the energized switching of the voltage regulating gear; the dial drives the groove wheel to move, and the groove wheel drives the moving contact and the coarse selection driving teeth of the fine selection contact assembly to move, and perform the non-energized selection of the voltage regulating gear; the moving contact of the fine selection contact assembly selects the corresponding static contact in the static contact group, and when the coarse selection driving teeth move to mesh with the corresponding gear on the incomplete gear mechanism, the coarse selection driving teeth drive the incomplete gear mechanism to move, and then drives the moving contact in the coarse selection contact assembly to select the corresponding static contact in the coarse selection contact assembly without current, and completes the non-energized selection of the voltage regulating gear together with the fine selection contact assembly, and completes the voltage adjustment.

2. The on-load tap-changing switch for distribution transformer according to claim 1, characterized in that: The voltage regulating gear position is controlled and positioned by the stepping motor.

3. The on-load tap-changing switch for distribution transformer according to claim 1, characterized in that: The gearbox includes a box body, a box cover, an electronic circuit board, a position sensor, and a gear set. The position sensor transmits the movement information of the gear set to the electronic circuit board, and the electronic circuit board performs analysis and processing to output the gear position of the on-load voltage regulating switch.

4. The on-load tap-changing switch for distribution transformer according to claim 1, characterized in that: The two cams in the switching switch assembly respectively control the on and off of the two vacuum interrupter chambers.

5. The on-load tap-changing switch for distribution transformer according to claim 1, characterized in that: The number of stationary contacts in the stationary contact group is the same as the number of teeth of the groove wheel.

6. An on-load voltage-changing distribution transformer, characterized in that: An on-load voltage-regulating distribution transformer using the on-load voltage-regulating switch for distribution transformers as claimed in any one of the preceding claims.

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