JP7781734B2 - On-load tap changer - Google Patents

Description

An embodiment of the present invention relates to an on-load tap changer.

On-load tap changers change taps while the transformer is in operation. On-load tap changers are required to keep costs down.

International Publication No. 2022/085288

The problem that this invention aims to solve is to provide an on-load tap changer that can reduce costs.

The on-load tap changer of this embodiment has a diverter switch, a tank body, a cover body, a drive shaft, a current-limiting resistor, a lower shield, and an upper shield. The tank body houses the diverter switch inside. The cover body closes the opening at the top of the tank body. The drive shaft is located outside the tank body and drives the diverter switch. The current-limiting resistors are arranged together above the diverter switch. The lower shield is detachable from the diverter switch, covers the top of the current-limiting resistor, and has a flat central portion on its upper surface. The upper shield is fixed to the bottom of the cover body, and has a flat central portion on its lower surface.

Cross section of an on-load tap changer. FIG. FIG. FIG. 2 is an exploded cross-sectional view of the lower shield and the change-over switch. FIG. 10 is a diagram illustrating a first operation of the push lock mechanism. FIG. 10 is a diagram illustrating a second operation of the push lock mechanism. FIG. 10 is a diagram illustrating a third operation of the push lock mechanism. FIG. 10 is a diagram illustrating a fourth operation of the push lock mechanism. FIG. 5 is a diagram illustrating a fifth operation of the push lock mechanism. FIG. 6 is a diagram illustrating a sixth operation of the push lock mechanism. FIG. 10 is a perspective view of a lower shield according to a modified example of the embodiment.

Hereinafter, an on-load tap changer according to an embodiment will be described with reference to the drawings.
1 is a perspective view of an embodiment of an on-load tap changer 10. The on-load tap changer 10 changes taps while the transformer is in operation. The on-load tap changer 10 is disposed inside the tank 5 of the transformer body 1. The on-load tap changer 10 is inserted into the tank 5 through an opening 5a in the top surface of the tank 5.

The on-load tap changer 10 includes a tap selector 11 and a diverter switch 30 .
The tap selector 11 selects a tap of the transformer. The diverter switch 30 switches the circuit to the selected tap. The tap selector 11 is located in the lower half of the on-load tap changer 10, and the diverter switch 30 is located in the upper half.

The on-load tap changer 10 has a tank body 20 , a head 22 , a cover body 23 , and a flange 24 .
The tank body 20 is cylindrical. The changeover switch 30 is housed inside the tank body 20. The lower end of the tank body 20 is closed by a bottom plate. The changeover switch 30 is fixed to the bottom plate of the tank body 20. The head 22 is connected to the upper end of the tank body 20. The head 22 is open. The lid 23 closes the openings of the tank body 20 and the head 22. The tank body 20 is sealed, and the interior of the tank body 20 is filled with insulating oil or insulating gas (hereinafter sometimes referred to as insulating oil, etc.). The lid 23 is detachable from the head 22. The flange 24 extends radially outward from the outer periphery of the head 22. The flange 24 closes the opening 5a of the tank 5. The tank 5 is sealed, and the interior of the tank 5 is filled with insulating oil, etc., which has high electrical insulation and arc-extinguishing properties.

The on-load tap changer 10 has a gear mechanism 13 , a drive shaft 14 , and a power introduction section 15 .
The gear mechanism 13 reduces the speed of power generated by an electric operating mechanism (not shown) and transmits it to the drive shaft 14. The gear mechanism 13 is disposed radially outside the head 22 and fixed to the flange 24. The upper end of the drive shaft 14 is connected to the gear mechanism 13. The drive shaft 14 extends downward from the gear mechanism 13. The lower end of the drive shaft 14 is connected to a power introduction unit 15. The power introduction unit 15 is disposed between the tank body 20 and the tap selector 11. The power introduction unit 15 introduces the power transmitted from the drive shaft 14 to the diverter switch 30 and the tap selector 11. The diverter switch 30 and the tap selector 11 operate using the power transmitted from the drive shaft 14.

The changeover switch 30 switches the connection of a pair of tap terminals for each phase of the three-phase AC. The changeover switch 30 has a current-limiting resistor 32 and a top plate 31.
A current-limiting resistor 32 is installed for each pair of three-phase tap terminals, and limits inrush current when the tap terminals are connected. A top plate 31 is disposed on top of the changeover switch 30. A plurality of current-limiting resistors 32 are disposed together on the top surface of the top plate 31. The plurality of current-limiting resistors 32 are disposed side by side in the circumferential direction, which is the horizontal direction.

When the drive shaft 14 is positioned inside the tank body 20, the current-limiting resistor 32 is positioned between the drive shaft 14 and the tank body 20. In this case, multiple current-limiting resistors 32 are arranged vertically, so the changeover switch 30 is vertically tall. In this embodiment, the drive shaft 14 is positioned outside the tank body 20. Multiple current-limiting resistors 32 are arranged horizontally, so the changeover switch 30 is vertically short.

When performing maintenance work on the changeover switch 30, the cover 23 is removed from the head 22 shown in Figure 2. Insulating oil and other materials are drained (recovered) from inside the tank body 20. Maintenance work on the changeover switch 30 is performed while the changeover switch 30 remains inside the tank body 20. In some cases, the changeover switch 30 is pulled upward through the opening in the head 22, and maintenance work on the changeover switch 30 is performed outside the tank 5.

The changeover switch 30 is housed inside the tank body 20. Therefore, maintenance work on the changeover switch 30 can be performed simply by draining the insulating oil from the tank body 20, without draining the insulating oil from the tank 5. The gear mechanism 13 is fixed to the flange 24, not to the lid body 23. Maintenance work on the changeover switch 30 can be performed by removing the lid body 23 without removing the gear mechanism 13. As a result, the maintenance work for the changeover switch 30 is reduced. In addition, the structure of the lid body 23 is simplified, reducing parts costs.

The earth insulation structure using the upper shield 26 and the lower shield 40 will now be described.
The tap selector 11 and diverter switch 30 shown in Figure 1 are connected to a transformer (not shown) housed in a tank 5. The head 22, cover 23, and flange 24 of the on-load tap changer 10 are connected to the tank 5. The tank 5 is grounded. An earth insulation structure is introduced inside the tank body 20 to reduce the electric field between the diverter switch 30 and the cover 23 and ensure insulation. The earth insulation structure is made up of an upper shield 26 and a lower shield 40.

FIG. 2 is a cross-sectional view of the upper half of the tank body 20.
The upper shield 26 is equivalent to the lower shield 40 (described below) turned upside down, with the exception of the central tube 45. The upper shield 26 and the lower shield 40 share common components, reducing costs. The upper shield 26 has a shield body 27 and feet 28. The central portion of the underside of the shield body 27 is flat. The feet 28 extend upward from the shield body 27 and are fixed to the bottom of the lid 23.

FIG. 3 is a perspective view of the lower shield 40. As shown in FIG.
The lower shield 40 is made of a metal material such as aluminum, and includes a shield body 41, legs 42, and a central tube 45.
The shield body 41 is in the shape of a petri dish that opens downward. The central portion of the upper surface of the shield body 41 is flat. A curved surface is formed between the upper surface and the outer circumferential surface of the shield body 41. As shown in FIG. 2 , the shield body 41 covers the upper portion of the current-limiting resistor 32.

Since the drive shaft 14 is positioned outside the tank body 20, there is no need to provide an insertion hole for the drive shaft 14 on the top surface of the shield body 41. To mitigate the electric field around the drive shaft 14, there is no need to form a curve on the top surface of the shield body 41 around the insertion hole for the drive shaft 14. The central portion of the top surface of the shield body 41 is flat. This simplifies the shape of the shield body 41 and reduces costs. The electric field inside the tank body 20 is mitigated.

As shown in Figure 3, the feet 42 extend downward from the peripheral edge of the shield body 41. Multiple feet 42 are arranged at equal angular intervals in the circumferential direction. The tips of the feet 42 can abut against the top plate 31 of the changeover switch 30 shown in Figure 2.

As shown in Figure 3, the central tube 45 has a cylindrical shape. The central tube 45 is arranged coaxially with the central axis of the shield body 41. The central tube 45 extends downward from the center of the shield body 41. Inside the central tube 45, the lever 52 of the push lock mechanism 50 (described below) and other components are arranged.

As shown in Figure 2, the upper shield 26 and the lower shield 40 are arranged facing each other in the vertical direction. As described above, the height of the diverter switch 30 is low, so the gap between the upper shield 26 and the lower shield 40 is large. As described above, the shapes of the shield body 27 of the upper shield 26 and the shield body 41 of the lower shield 40 are simplified. As a result, the electric field between the diverter switch 30 and the cover 23 inside the tank body 20 is alleviated, ensuring insulation. To alleviate the electric field inside the tank body 20, there is no need to provide an external shield outside the tank body 20. There is no need to adjust the gap between the ring-shaped external shield and the outer periphery of the tank body 20 to a constant value. The cost of the on-load tap changer 10 is reduced.

The push lock mechanism 50 will now be described.
4 is an exploded cross-sectional view of the lower shield 40 and the diverter switch 30. When performing maintenance work on the diverter switch 30, the lower shield 40 is attached to and detached from the diverter switch 30. Before the maintenance work, the lower shield 40 is removed from the diverter switch 30. After the maintenance work, the lower shield 40 is attached to the diverter switch 30. The lower shield 40 can be attached to and detached from the diverter switch 30 by a push lock mechanism (heart cam mechanism) 50.

The push lock mechanism 50 includes a lever 52 , a horizontal spring 57 , a vertical spring 59 , and a heart cam piece (heart cam) 62 .
The lever 52 is disposed inside the central tube 45 of the lower shield 40. The lever 52 extends in a substantially vertical direction. The lever 52 has a rotation shaft 53 at its upper end. The lever 52 is rotatable around the rotation shaft 53. The rotation shaft 53 extends horizontally, and both ends are supported by the central tube 45. The lever 52 has an engagement pin 55 at its lower end. The engagement pin 55 protrudes from the lever 52 parallel to the rotation shaft 53. The lever 52 has an arm 56 midway in the vertical direction. The arm 56 extends from the lever 52 in a horizontal direction perpendicular to the rotation shaft 53. A pair of arms 56 extend on either side of the lever 52.

The horizontal spring 57 is expandable and contractible in the horizontal direction. The horizontal spring 57 is arranged around the arm portion 56. A pair of horizontal springs 57 is arranged around the corresponding arm portion 56. The horizontal springs 57 are arranged between the lever 52 and the central cylinder 45 in a compressed state.
The vertical spring (elastic member) 59 can expand and contract in the up-down direction (vertical direction). The upper end of the vertical spring 59 is fixed to the lower end of the central cylinder 45. The lower end of the vertical spring 59 can abut against the top plate 31 of the changeover switch 30.

The changeover switch 30 has a central hole 35 above the top plate 31. The current-limiting resistors 32 above the top plate 31 are arranged around the central hole 35, and the central hole 35 is formed in the center of the current-limiting resistors 32. The central hole 35 is coaxial with the central axis of the changeover switch 30. A base cam 61 is arranged at the lower end inside the central hole 35. The base cam 61 is fixed to the top plate 31.
The heart cam piece 62 is attached to the base cam 61. The thickness direction of the heart cam piece 62 is parallel to the rotation axis 53 of the lever 52. A passage 63 for the engagement pin 55 of the lever 52 is formed around the heart cam piece 62.

5 to 10 are explanatory diagrams showing first to sixth operations of the push lock mechanism 50. FIG.
As shown in Figure 5, the periphery of the heart cam piece 62 is formed with a peak 64, a first inclined portion 67r, an engagement groove 65, and a second inclined portion 67s. The r-direction and s-direction are defined as follows with respect to the central axis CL of the lower shield 40 and the diverter switch 30. The r-direction is the direction in which the peak 64 of the heart cam piece 62 is located with respect to the central axis CL. The s-direction is the direction in which the engagement groove 65 of the heart cam piece 62 is located with respect to the central axis CL. The r-direction and s-direction are opposite each other.

The apex 64 is located at the upper end of the heart cam piece 62. The apex 64 is disposed offset in the s direction from the central axis CL.
The engagement groove 65 is located at the lower end of the heart cam piece 62. The engagement groove 65 is positioned offset in the r direction from the central axis CL. The engagement groove 65 opens downward. The engagement pin 55 of the lever 52 can engage with the engagement groove 65.

The first inclined portion 67r connects the top portion 64 and the engagement groove 65 in the r direction of the top portion 64 and the engagement groove 65.
The second inclined portion 67s connects the top portion 64 and the engagement groove 65 in the s direction of the top portion 64 and the engagement groove 65.

The operation of the push-lock mechanism 50 when the lower shield 40 shown in FIG. 4 is attached to the diverter switch 30 will be described.
The worker attaches a suction cup, which adheres by negative pressure, to the upper surface of the shield body 41 of the lower shield 40. A magnet may be attached instead of the suction cup. The worker holds the suction cup and inserts the central tube 45 of the lower shield 40 into the central hole 35 of the changeover switch 30. By handling the lower shield 40 via the suction cup, damage to the upper surface of the shield body 41 is suppressed. Disturbance of the electric field around the shield body 41 is suppressed.

5, the engagement pin 55 of the lever 52 abuts against the heart cam piece 62. The engagement pin 55 abuts against the first inclined portion 67r of the heart cam piece 62.
The worker pushes the lower shield 40 downward toward the changeover switch 30 .
6, the engaging pin 55 is guided by the first inclined portion 67r, and the lever 52 rotates in the r direction. The first horizontal spring 57r of the lever 52 in the r direction is compressed.

As shown in Figure 7, when the engagement pin 55 passes the lower end of the first inclined portion 67r, the first horizontal spring 57r pushes the lever 52 back in the direction s. The engagement pin 55 engages with the engagement groove 65 of the heart cam piece 62. The lower end of the vertical spring 59 shown in Figure 4 abuts against the top plate 31 of the changeover switch 30, compressing the vertical spring 59. This completes the attachment of the lower shield 40 to the changeover switch 30.

The operation of the push lock mechanism 50 when the lower shield 40 is removed from the diverter switch 30 will be described.
The worker pushes the lower shield 40 downward toward the changeover switch 30 .
8, the engagement pin 55 comes out of the engagement groove 65. The first horizontal spring 57r pushes the lever 52 in the s direction.

9, the engagement pin 55 rides up onto the second inclined portion 67s. The vertical spring 59 shown in FIG. 4 pushes the lower shield 40 upward.
10, the engaging pin 55 is guided by the second inclined portion 67s, and the lever 52 moves upward. In this manner, the removal of the lower shield 40 from the diverter switch 30 is completed.

Figure 11 is a perspective view of a lower shield 40 in a modified embodiment. In the lower shield 40 of the embodiment shown in Figure 3, the vertical spring 59 is fixed to the central tube 45. In the modified lower shield 40 shown in Figure 11, the vertical spring 59 is fixed to the foot portion 42. Descriptions of the modified embodiment that are similar to the embodiment may be omitted.

The lower shield 40 has protrusions 58 that protrude downward from the lower ends of the multiple feet 42. Vertical springs 59 are arranged around the protrusions 58. Vertical springs 59 are arranged at the lower ends of all of the feet 42. The upper ends of the vertical springs 59 are fixed to the feet 42. The lower ends of the vertical springs 59 can abut against the top plate of the changeover switch 30. The vertical springs 59 of the modified example function in the same way as the vertical springs of the embodiment.

As described above in detail, the on-load tap changer 10 of this embodiment includes the diverter switch 30, the tank body 20, the cover body 23, the drive shaft 14, the current-limiting resistor 32, the lower shield 40, and the upper shield 26. The tank body 20 houses the diverter switch 30 inside. The cover body 23 closes the opening at the top of the tank body 20. The drive shaft 14 is located outside the tank body 20 and drives the diverter switch 30. The current-limiting resistors 32 are arranged together at the top of the diverter switch 30. The lower shield 40 is detachable from the diverter switch 30, covers the top of the current-limiting resistor 32, and has a flat central portion on its top surface. The upper shield 26 is fixed to the bottom of the cover body 23, and has a flat central portion on its bottom surface.

The drive shaft 14 is positioned outside the tank body 20. There is no need to provide a through-hole for the drive shaft 14 in the upper shield 26 and lower shield 40. The central portion of the lower surface of the upper shield 26 is flat. The central portion of the upper surface of the lower shield 40 is flat. The shapes of the upper shield 26 and lower shield 40 are simplified. The cost of the on-load tap changer 10 is reduced.

The drive shaft 14 is positioned outside the tank body 20. Multiple current-limiting resistors 32 are arranged horizontally above the diverter switch 30. The diverter switch 30 is lowered vertically. The distance between the upper shield 26 and the lower shield 40 is increased. As described above, the shapes of the upper shield 26 and the lower shield 40 are simplified. As a result, the electric field between the diverter switch 30 and the cover 23 inside the tank body 20 is alleviated. There is no need to provide an external shield outside the tank body 20 to alleviate the electric field inside the tank body 20. The cost of the on-load tap changer 10 is reduced.

The on-load tap changer 10 further has a push-lock mechanism 50 that enables the lower shield 40 to be attached to and detached from the diverter switch 30 by pushing the lower shield 40 toward the diverter switch 30 .
There is no need to provide mounting holes or the like on the top surface of the lower shield 40 for attaching and detaching the lower shield 40 to the diverter switch 30. The shape of the lower shield 40 is simplified, reducing the cost of the on-load tap changer 10. The lower shield 40 can be attached and detached with a simple operation, making maintenance work on the diverter switch 30 easier.

The push lock mechanism 50 is disposed in the center of the lower shield 40 and the diverter switch 30. The lower shield 40 has downwardly extending feet 42 disposed at equal angular intervals on the periphery.
The attaching/detaching operation and posture of the lower shield 40 are stabilized.

The lower shield 40 has a central cylinder 45 extending downward from the center thereof. The upper end of the lower shield 40 is fixed to the central cylinder 45 and has a vertical spring 59 that is expandable and contractible in the up-down direction.
The lower shield 40 may have an upper end fixed to the foot 42 and may have a vertical spring 59 that is expandable and contractible in the up and down direction.
The operation of the push lock mechanism 50 is stabilized.

At least one of the embodiments described above has an upper shield 26 and a lower shield 40 with flat central portions. This reduces the cost of the on-load tap changer 10.

While several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments may be embodied in a variety of other forms, and various omissions, substitutions, and modifications may be made without departing from the spirit of the invention. These embodiments and their variations are within the scope of the invention and its equivalents as defined in the claims, as well as the scope and spirit of the invention.

10...on-load tap changer, 14...drive shaft, 20...tank body, 23...lid body, 26...upper shield, 30...changer switch, 32...current-limiting resistor, 40...lower shield, 42...foot, 45...central cylinder, 50...push-lock mechanism, 59...vertical spring (elastic member).

Claims (5)

A changeover switch;
a tank body that houses the change-over switch inside;
a lid that closes an opening at the top of the tank body;
a drive shaft disposed outside the tank body and driving the changeover switch;
current-limiting resistors arranged collectively on the upper part of the change-over switch;
a lower shield that is detachable from the change-over switch, covers an upper portion of the current-limiting resistor, and has a flat central portion on its upper surface;
An upper shield fixed to the lower part of the lid body, the central part of the lower surface of which is flat,
On-load tap changer. The switch further includes a push lock mechanism that enables the lower shield to be attached to and detached from the switch by pushing the lower shield toward the switch.
2. An on-load tap changer according to claim 1. the push lock mechanism is disposed at a center portion of the lower shield and the diverter switch,
The lower shield has downwardly extending feet arranged at equal angular intervals around its periphery.
3. An on-load tap changer according to claim 2. The lower shield has a central tube extending downward from a central portion,
The lower shield has an elastic member whose upper end is fixed to the central cylinder and which is expandable and contractible in the vertical direction.
4. An on-load tap changer according to claim 3. The lower shield has an elastic member whose upper end is fixed to the foot portion and which is stretchable in the vertical direction.
4. An on-load tap changer according to claim 3.