A special on-load voltage regulating switch for distribution transformer and on-load voltage regulating distribution transformer

Abstract

This invention discloses a dedicated on-load tap changer for distribution transformers and an on-load tap-changing distribution transformer. The switch includes a mounting main board, an insulating backplate, a drive mechanism assembly, a selector switch assembly, a switching assembly, and a transition element. The drive mechanism assembly includes a stepper motor, a gearbox, a bevel gear, a drive gear, and a square shaft. The rotational motion of the stepper motor is transmitted to the drive gear via the gearbox and bevel gear. The drive gear drives the square shaft to rotate, which in turn drives the selector switch assembly and the switching assembly to complete the switching of the tap changer position. This invention achieves miniaturization of the on-load tap changer, allowing it to be installed in the distribution transformer without altering its conventional shape and volume. It enables frequent voltage adjustments under load, stabilizing the supply voltage, reducing losses, and achieving wide-range, multi-position, and precise voltage regulation. Furthermore, the switch's lifespan is equal to that of the distribution transformer itself, requiring no maintenance during its lifespan, thus improving the reliability of on-load tap changing in distribution transformers.

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 explain its driving transmission mechanism. The driving part of the on-load voltage regulator is one of its core components. If the driving mechanism adopts spring energy storage or permanent magnet driving mode, the impact force is large during the switching process, which will greatly reduce the performance of the on-load voltage regulator and affect the service life of the on-load tap changer. The design life of the distribution transformer is at least 30 years, and the reliability requirements of the on-load tap-changing switch are higher. The function realized by the above two invention patents is that the transformer performs voltage regulation uninterruptedly, but its reliability is not explained. The on-load tap-changing switch of the above two patents uses a single vacuum interrupter and its mechanical mechanism for switching in each phase switching component. It switches from N taps to N+1 taps, and the vacuum interrupter needs to be opened and closed twice. The current is turned on and off in the vacuum interrupter, which has higher requirements on the contacts of the vacuum interrupter. Compared with the vacuum interrupter that is only connected and disconnected once during the gear shifting process, its reliability is relatively 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 also increases the length of the switch. The two rods or bars used to fix the switch components are both cylindrical, which increases the overall height of the switch. It can be seen from its specification and drawings that its structural design does not invent or create a miniaturized on-load tap changer. The size of the on-load tap changer will affect the size, production cost and installation space of the distribution transformer. For a large number of distribution transformers, a miniaturized and highly reliable on-load tap changer is required. Summary of the invention

[0006] The object of the present invention is to provide an on-load voltage regulating switch and an on-load voltage regulating distribution transformer for distribution transformers, so as to solve the problem of the on-load voltage regulating distribution transformers in the prior art requiring regular maintenance due to on-load voltage regulating switching, and at the same time solve the problem of the on-load voltage regulating switches in the prior art being large in size and inconvenient to install, so as to realize 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, realize the long life and maintenance-free characteristics of the on-load voltage regulating switch, and make 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 stepper motor is provided with a motor protection shell outside, and a connector socket is provided on the motor protection shell, the connector socket is located in the lower shell of the motor protection shell, an external control cable is connected to the connector plug, and the connector plug is connected to the connector socket with the connector facing upward;

[0011] The gearbox includes a box body, a box cover, an electronic circuit board, a position sensor, and a gear set;

[0012] 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;

[0013] 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;

[0014] The stepper motor is mounted on the gearbox, and the gearbox is mounted on the mounting mainboard;

[0015] The selection switch assembly and the switching switch assembly are fixedly mounted on the mounting mainboard;

[0016] The insulating back plate is fixedly connected to one end of the selection switch assembly and the switching switch assembly;

[0017] The transition element is fixedly mounted on one side of the switch mainboard in the switch assembly;

[0018] The square shaft runs through the selection switch assembly and the switching switch assembly;

[0019] The driving gear is sleeved on the square shaft;

[0020] 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, thereby driving the selection switch assembly and the switching switch assembly to operate, thereby completing the conversion of the voltage regulating gear.

[0021] According to a preferred implementation manner of the present invention, the voltage regulating gear position is positioned by controlling the stepping motor.

[0022] According to a preferred embodiment of the present invention, each group of the switching switch assembly includes a switching switch mainboard, a vacuum arc extinguishing chamber, a cam, a roller, a transmission arm, a support shaft, an arc extinguishing chamber pull rod, an arc extinguishing chamber contact pressure spring, a pull rod bracket, and an arc extinguishing chamber mounting base. Except for the switching switch mainboard, each of the other components has two components, and each component is located on the same side of the switching switch mainboard. The transition element is installed on the other side of the switching switch mainboard.

[0023] According to a preferred embodiment of the present invention, the square shaft drives the two cams to rotate, and the two cams drive the rollers to move in a sequential manner. The rollers drive the arc extinguishing chamber pull rod to move up and down through the transmission arm, thereby driving the arc extinguishing chamber contact pressure spring to move, thereby controlling the on and off of the vacuum arc extinguishing chamber.

[0024] According to a preferred embodiment of the present invention, 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 coarse selection drive tooth, an incomplete gear mechanism, and a coarse selection contact assembly, the groove wheel mechanism includes a dial and a groove wheel, and the two groups of the groove wheel mechanisms are respectively installed on both sides of the selection switch main board, the coarse selection drive tooth is installed and fixed on the groove wheel of one of the groove wheel mechanisms, the incomplete gear mechanism is installed and fixed on one side of the selection switch main board, and the coarse selection contact assembly is fixed to one side of the selection switch main board through a fixing column.

[0025] According to a preferred implementation manner of the present invention, 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.

[0026] 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 mounted in the grooves on both sides of the selection switch mainboard by conductive bolts, and the static contacts are flush with the surface of the selection switch mainboard after installation; the number of the static contacts is the same as the number of teeth on the groove wheel, and when selecting a gear, the groove wheel drives the moving contact to rotate to select the corresponding static contact in the static contact group.

[0027] According to a preferred embodiment of the present invention, the roughing 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 groove wheel drives the roughing selection drive tooth to move to engage with the corresponding gear on the incomplete gear mechanism, the roughing selection drive tooth drives the incomplete gear mechanism to move, and the incomplete gear mechanism drives the moving contact in the roughing selection contact assembly to select the corresponding stationary contact in the roughing selection contact assembly without current.

[0028] 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.

[0029] 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 on the box cover of the distribution transformer, the switch body is located below the box cover, the driving part of the switch, the stepper motor, is located above the box cover, and the stepper motor is provided with a fully protective motor protection shell, and a connector is provided below the motor protection shell. It has a unique waterproof and dustproof design and high protection performance; the on-load voltage regulating switch is installed in the distribution transformer as much as possible without changing the shape and volume of the conventional distribution transformer, which greatly reduces the production cost increased by the large volume of the switch; it achieves more than 600,000 trouble-free and maintenance-free continuous voltage regulation actions, and can be maintenance-free within the life cycle of the distribution transformer, thereby improving the reliability of the on-load voltage regulation of the distribution transformer; at the same time, it realizes the wide voltage regulation of the distribution transformer, which can achieve 17 gears of ±8×2.5% wide voltage regulation, and frequent voltage adjustment under load conditions, which stabilizes the power supply voltage and reduces losses. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] 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;

[0031] 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;

[0032] Figure 3 It is a schematic diagram of a fully protective housing of a stepping motor of an on-load tap-changing switch dedicated to a distribution transformer of the present invention;

[0033] Figure 4 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;

[0034] Figure 5 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);

[0035] Figure 6 It is a schematic diagram of the transition element on the other side of the switching switch mainboard of the on-load tap-changing switch dedicated to the distribution transformer of the present invention;

[0036] Figure 7 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;

[0037] Figure 8 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;

[0038] Fig. 9 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;

[0039] Fig.10 It is a structural schematic diagram of one side of the selector switch assembly of the on-load tap-changing switch dedicated to the distribution transformer of the present invention without the groove wheel and other components;

[0040] Fig.11 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

[0041] 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.

[0042] Figures 1 to 10 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 voltage regulating switch for distribution transformer includes an installation main board 1, an insulating back plate 2, a driving mechanism component 3, a selection switch component 4, a switching switch component 5, and a transition element 6; the driving mechanism component includes a stepping motor 31, a gearbox 32, a bevel gear 33, a driving gear 34, and a square shaft 35. The selection switch component 4, the switching switch component 5, and the transition element 6 each have three groups, which respectively complete the selection and switching of the three-phase voltage regulating gears.

[0043] See also Figure 3 As shown, the present invention adds a full protection design for the stepper motor. A motor protection shell is provided outside the stepper motor 31. The motor protection shell is fixedly installed on the gearbox by fastening screws. The motor protection shell is divided into an upper shell 311 and a lower shell 312. A socket of a connector 313 is provided on the lower shell 312. The socket of the connector 313 is designed to face downward. Its design position and direction effectively achieve the effect of waterproofing and dustproofing. The relevant gear information feedback line of the on-load voltage regulating switch and the stepper motor control line 314 are connected to the socket of the connector 313. The plug of the connector 313 is connected to the external control cable. The plug of the connector 313 faces upward and is connected to the socket of the connector 313. Figure 3 shown.

[0044] See also Figure 4As 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. The position sensor 324 transmits the movement information of the gear set 325 to the electronic circuit board 323, and the electronic circuit board 323 analyzes and processes and outputs the gear position of the on-load voltage regulating switch.

[0045] See also Figure 5 , Figure 6 As shown, each group of switching switch components 5 includes a switching switch main board 51, vacuum interrupters 521, 522, cams 531, 532, rollers 541, 542, transmission arms 551, 552, support shafts 561, 562, interrupter pull rods 571, 572, interrupter contact pressure springs 581, 582, pull rod brackets 591, 592, and interrupter mounting bases 5101, 5102. Each component is located on the switching switch main board 51. On the same side, the transition element 6 is installed on the other side of the switching switch mainboard 51; the square shaft 35 drives the cams 531 and 532 to rotate, and the cams 531 and 532 respectively drive the rollers 541 and 542 to move in a timely manner. The rollers 541 and 542 drive the arc extinguishing chamber pull rods 571 and 572 to move up and down through the transmission arms 551 and 552, thereby driving the arc extinguishing chamber contact pressure springs 581 and 582 to control the on and off of the vacuum arc extinguishing chambers 521 and 522.

[0046] See also Figures 7 to 10 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 stationary contact group 443 includes a plurality of stationary contacts. 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.10The 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; the two groups of groove wheel mechanisms 42, 43 are respectively installed on both sides of the selection switch main board 41, the moving contacts 441, 442 are respectively fixedly installed on the groove wheels 422, 432, the static contacts in the static contact group 443 are fixedly installed in the grooves on both sides of the selection switch main board 41 by conductive bolts 445, and the static contacts in the static contact group 443 are flush with the surface of the selection switch main board 41 after installation; the rough selection drive teeth 45 are installed and fixed on the groove wheels 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 rough selection contact assembly 47 is fixed on one side of the selection switch main board 41 by a fixing column; the rough selection drive teeth 45, the incomplete gear mechanism 46, and the rough selection contact assembly 47 are on the same side of the selection switch main board 41; Fig.10 The internal structure of the groove wheel 422 or 432 of the groove wheel mechanism 42 or 43 is removed. It can be clearly seen that the static contacts in the static contact group 443 are fixed in the groove of the selection switch main board 41, and it can be seen that the moving contact 441 in the fine selection contact assembly 44 is connected to a static contact in the static contact group 443.

[0047] 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.

[0048] 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 are driven by rollers 541, 542, transmission arms 551, 552, arc extinguishing chamber pull rods 571, 572, and arc extinguishing chamber contact pressure springs 581, 582. The vacuum interrupter chambers 52 and 53 are pushed on and off to complete the energized switching of the voltage regulating gear; the dials 421 and 431 push the groove wheels 422 and 432 to move, and the groove wheels 422 and 432 drive the moving contacts 441 and 442 in the fine selection contact assembly 44 and the coarse selection drive teeth 45 to move, 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 teeth 45 move to engage with the corresponding gear on the incomplete gear mechanism 46, and the coarse selection drive teeth 45 drive the incomplete gear mechanism 46 to move, and then drive the moving contact 471 in the coarse selection contact assembly 47 to select the corresponding static contact 472 or static contact 473, to complete the non-energized selection of the voltage regulating gear and complete the voltage adjustment.

[0049] See also Fig.11 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 521 and 522 in the switching switch assembly 5.

[0050] The timing of switching from the N+1 tap of the voltage regulating winding to the N tap is:

[0051] 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.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] The above is an explanation of the fine selection gear switching process of the on-load voltage regulating switch. The rough selection part of the selection switch assembly is designed according to the conventional on-load voltage regulation method: coarse and fine voltage regulation principle, positive and negative voltage regulation principle. Both the fine selection part and the rough selection part of the selection switch assembly move or select the corresponding contacts in the no-current state. It 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, which will not pollute the transformer oil, and there is no need to perform regular oil filter maintenance or replace the filter element, which greatly saves the operation and maintenance costs.

[0059] When designing a dedicated on-load voltage-regulating switch 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 the flexible drive and precise positioning characteristics of the stepper motor 31 to drive and convert the voltage-regulating gear and control the positioning, greatly reducing the impact force on its related components (switching switch components, selection switch components) during the driving and transmission process of the on-load voltage-regulating switch, and improving the actual service life and reliability of each switch component; 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, omitting the conventional position switch feedback device with high failure rate and unreliability, greatly improving the life span and operation reliability of the on-load voltage-regulating switch; a motor protective housing is provided outside the stepper motor 31, and the motor protective housing belongs to a full protection design structure, and is provided below it. Connector, this design position has the best waterproof and dustproof effect; two vacuum arc extinguishing chambers 521 and 522 are arranged in the switching switch assembly 5. When the voltage regulating gear is switched, the two vacuum arc extinguishing chambers 521 and 522 are only actuated once, compared with other vacuum arc extinguishing chambers that only have one vacuum arc extinguishing chamber, each gear switching 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; the present invention adopts a mounting mainboard with sufficient tolerance strength to fix and install various components to reduce the overall height of the on-load voltage regulating switch; at the same time, the rough selection and fine selection related components of the on-load voltage regulating switch are all arranged on the same selection switch mainboard. Compared with switches arranged on different mounting mainboards, the structural design of the present invention is simple and compact, the length of the switch is reduced, and the overall design of the switch is miniaturized. By selecting the above-mentioned scheme, the present invention realizes the characteristics of miniaturization, maintenance-free, and high reliability of the on-load voltage regulating switch, and is suitable for a moderately large distribution transformer. Improvements can be made in the technical field based on 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 falls within the protection scope of the present invention.

[0060] 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 distribution transformers 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 slot wheel and the corresponding static contacts can be increased, and the volume of the switch will also increase accordingly. Figures 1 to 10 It is a preferred implementation scheme of the present invention. The number of gears can be increased or decreased according to user needs. The operating principle of the on-load voltage regulating switch can be changed and improved within the technical field of this invention and still belongs to the protection scope of the present invention.

[0061] 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 regulating switch for distribution transformer, which can realize 17-level voltage regulation, characterized in that: 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 stepper motor is provided with a motor protection shell outside, and a connector socket is provided on the motor protection shell, the connector socket is located in the lower shell of the motor protection shell, an external control cable is connected to the connector plug, and the connector plug is connected to the connector socket with the connector facing upward; 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; 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; The stepper motor is mounted on the gearbox, and the gearbox is mounted on the mounting mainboard; The selection switch assembly and the switching switch assembly are fixedly mounted on the mounting mainboard; 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 drive tooth, an incomplete gear mechanism, and a rough selection contact assembly. The rough selection contact assembly includes a moving contact, two stationary contacts, and a contact fixing plate. The fine selection contact assembly includes two moving contacts and a stationary contact group. Each group of the switching switch assembly includes a switching switch mainboard, a vacuum interrupter, a cam, a roller, a transmission arm, a support shaft, an interrupter pull rod, an interrupter contact pressure spring, a pull rod bracket, and an interrupter mounting base. Except for the switching switch mainboard, each of the other components has two components, and each component is located on the same side of the switching switch mainboard. The transition element is installed on the other side of the switching switch mainboard; The insulating back plate is fixedly connected to one end of the selection switch assembly and the switching switch assembly; The transition element is fixedly mounted on one side of the switch mainboard in the switch assembly; The square shaft runs through the selection switch assembly and the switching switch assembly; The driving gear is sleeved on the square shaft; The rotational motion of the stepper 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 cam and the groove wheel mechanism to rotate. The cam pushes the vacuum interrupter to be turned on and off through the roller, the transmission arm, the interrupter pull rod, and the interrupter contact pressure spring, so as to complete the energized switching of the voltage regulating gear. The groove wheel mechanism drives the moving contact and the coarse selection drive tooth in the fine selection contact assembly to move, and the moving contact in the fine selection contact assembly selects the corresponding static contact in the static contact group. When the corresponding gear is converted, when the coarse selection drive tooth moves to mesh with the corresponding gear on the incomplete gear mechanism, the coarse selection drive tooth drives 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, so as to complete the non-energized selection of the voltage regulating gear and 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 square shaft drives the two cams to rotate, and the two cams drive the rollers to move in a sequential manner. The rollers drive the arc extinguishing chamber pull rod to move up and down through the transmission arm, thereby driving the arc extinguishing chamber contact pressure spring to control the on and off of the vacuum arc extinguishing chamber.

4. The on-load tap-changing switch for distribution transformer according to claim 1, characterized in that: The groove wheel mechanism includes a dial and a groove wheel. Two groups of the groove wheel mechanisms are respectively installed on both sides of the selection switch main board. The coarse selection drive tooth is installed and fixed on the groove wheel of one of the groove wheel mechanisms. The incomplete gear mechanism is installed and fixed on one side of the selection switch main board. The coarse selection contact assembly is fixed on one side of the selection switch main board through a fixing column.

5. The on-load tap-changing switch for distribution transformer according to claim 1, characterized in that: 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.

6. The on-load tap-changing switch for distribution transformer according to claim 4, characterized in that: The two moving contacts in the fine selection contact assembly 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 mounted in the grooves on both sides of the selection switch mainboard through conductive bolts. After installation, the static contacts are flush with the surface of the selection switch mainboard; 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.

7. The on-load tap-changing switch for distribution transformer according to claim 1, wherein the moving contact and the two stationary contacts in the rough selection contact assembly are both mounted on the contact fixing plate.

8. 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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