JP2009088123A - On-load tap changer, change contact for on-load tap changer and producing apparatus thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an on-load tap changer achieving a change contact having advantageous sliding properties and long service life while simultaneously preventing the formation of silver sulfide and being excellent in reliability with a compact and simple constitution. <P>SOLUTION: In the on-load tap changer, a silver plating layer 22 is disposed over the whole surface of a plate-shaped contact mother material 21 in a moving contact 11 and further, a rigid carbon coating film layer 23 such as diamond-like carbon is disposed over the whole outside surface of the silver plating layer 22. Among them, the silver plating layer 22 is formed to have a thickness of 5 to 50 μm and a Vickers hardness of ≥90 while the rigid carbon coating film layer 23 is formed to have a thickness of 0.1 to 4 μm and a Vickers hardness of ≥1,000. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an on-load tap switching device and a manufacturing technique thereof, and more particularly to a switching contact used on an on-load tap switching device and an apparatus for manufacturing the same.

  In general, a transformer for a transmission / transformer system is provided with a load tap switching device for switching the tap of a tap winding at the time of load to perform voltage adjustment. If this on-load tap changer breaks down, there will be a problem with voltage adjustment, which may cause a serious problem such as a power failure in the transmission and substation system. Therefore, the on-load tap changer is required to have high reliability in terms of performance.

  In recent years, the liberalization of electric power has progressed, and in the electric power equipment field, it is desired to make the equipment compact and improve the economy. For this reason, there is an increasing demand for downsizing and cost reduction with respect to the on-load tap changer, which is one of the power devices. In other words, in the on-load tap switching device, in addition to the above-described requirement for improving reliability, it is expected to achieve downsizing and cost reduction, and reliably perform the voltage adjustment function with a small and simple configuration. It is demanded.

  Under the circumstances as described above, the switching contact provided in the on-load tap switching device is generally provided with a silver plating layer on the surface thereof in order to improve the energization performance. The switching contact is a contact that switches the tap of the transformer tap winding, and is provided in both the switching switch and the tap selector that constitute the on-load tap switching device. This switching contact is an important component that greatly affects the performance and downsizing of the entire on-load tap switching device, and various proposals have been made heretofore.

  For example, in Patent Document 1, since the fixed contact is a plate-like member protruding toward the switching contact, the contact area between the contact and the switching contact is widened, and the contact surface pressure between the fixed contact and the switching contact can be stabilized. it can. Therefore, it is not necessary to increase the supporting member of the switching contact in order to ensure the contact surface pressure, and it is possible to contribute to downsizing of the device. Further, the amount of wear can be reduced with the stabilization of the contact surface pressure between the fixed contact and the switching contact. For this reason, the contact life is extended, the maintenance interval can be increased, and this is economically advantageous. By providing such a switching contact, it is possible to contribute to improving the reliability of the on-load tap switching device.

  By the way, when the on-load tap switching device is an oil shut-off system in which insulating oil is filled as an insulator inside the device, there are the following problems. In other words, since the insulating oil contains sulfur, when the insulating oil contacts the switching contact inside the on-load tap switching device, the sulfur in the insulating oil reacts with the silver plating layer applied to the switching contact. As a result, silver sulfide may be generated.

If this silver sulfide adheres to the switching contact and intervenes in the current-carrying portion, the current-carrying performance of the on-load tap switching device will be hindered. Therefore, in the switching contact having the silver plating layer, it is necessary to reduce the generation amount of silver sulfide as much as possible by reducing the contact surface with sulfur. Therefore, conventionally, a technique has been considered in which a coating portion is applied to a part of the silver plating layer to suppress the reaction between sulfur and silver.
JP 2001-217130 A

  However, the following problems are pointed out in the prior art in which a coating portion is formed on a silver plating layer. In other words, when the coating part is formed on the silver plating layer, the generation amount of silver sulfide is reduced by the amount of contact surface between silver and sulfur, but on the other hand, excessive resistance force is generated during the switching operation in the coating part. Thus, the frictional force and the amount of wear at the switching contact are increased. Therefore, the aging of the switching contact is easy to progress, the life is shortened and the sliding characteristics are lowered. Thereby, there existed a possibility that the operativity of the tap switching apparatus at the time of load might become unstable.

  The present invention has been proposed in order to solve the above-mentioned problems, and the object thereof is to realize a switching contact having good sliding characteristics and long life while suppressing the generation of silver sulfide, An object of the present invention is to provide an on-load tap changer having a simple configuration and excellent reliability. Another object of the present invention is to provide an apparatus for producing a switching contact for on-load tap switching device capable of efficiently producing a switching contact having good sliding characteristics without producing silver sulfide. There is.

  In order to achieve the above-mentioned object, the present invention provides a tap switching device at the time of loading comprising a switching switch and a tap selector, wherein the switching switch and the tap selector are provided with a switching contact constituting an energization circuit. The switching contact is provided with a silver plating layer, and the silver plating layer is provided with a hard carbon coating layer.

  The hard carbon coating is also called diamond-like carbon and has characteristics such as low friction and high hardness, low resistance, and low wear. Therefore, the switching contact provided with the hard carbon coating layer can exhibit good sliding characteristics and long life. In addition, since the hard carbon film has excellent corrosion resistance, the silver plating layer provided with the hard carbon film layer hardly reacts with sulfur in the insulating oil, and can suppress the generation amount of silver sulfide.

  According to the present invention, the formation of silver sulfide can be suppressed even when the switching contact is in the insulating oil by a very simple configuration in which a hard carbon coating layer is applied to the silver plating layer of the switching contact, and sliding is possible. It was possible to provide an on-load tap changer with improved characteristics and long life and excellent reliability with a small and simple configuration.

Hereinafter, the best mode (hereinafter referred to as an embodiment) according to the present invention will be specifically described with reference to FIGS.
(1) First Embodiment [Configuration]
The first embodiment will be described with reference to FIGS. First, the outline of the on-load tap switching device applied to the present invention will be described with reference to FIGS.

  As shown in FIG. 2, the on-load tap switching device includes a switching switch 1 that cuts off the load current at the time of loading and transfers the current to an adjacent tap, and a tap selection that selects the tap of the tap winding to the required position. It consists of a container 2. Both the switching switch 1 and the tap selector 2 are attached to the transformer main body tank 4. Note that the interiors of the switching switch 1, the tap selector 2, and the transformer main body tank 4 are filled with an insulating material such as insulating oil.

  The switching switch 1 is provided with a current limiting resistor 3. In addition, a reduction gear 5 connected to an operation mechanism (not shown) is provided on the upper part of the switching switch 1, and the energy storage device 6 having an energy storage spring 6 b is connected to the reduction gear 5 via a drive shaft 7. Are connected. Further, below the energy storage device 6, there is provided a contact portion 8 that switches the current by the driving force of the energy storage device 6.

  The contact portion 8 includes a plurality of switching contacts 11. More specifically, the contact portion 8 includes a cam 9 that is rotated by the driving force of the energy storage device 6, a current collecting ring 54 that rotates in conjunction with the cam 9, a plurality of vacuum valve mechanisms 10, a plurality of switching contacts 11, and a plurality of switching contacts 11. The movable contact 12 and the insulating ring 74 are included. Further, the tap selector 2 is connected to an operation mechanism (not shown) similarly to the switching switch 1. Although not shown, in the tap selector 2, a plurality of switching contacts and movable contacts are provided in the same manner as the switching switch 1 in order to select a tap.

  Here, the configuration of the switching contact 11 and the movable contact 12 will be described with reference to FIG. FIG. 3 shows a cross section of the switching contact portion of this embodiment. In the present embodiment, the configuration of a three-phase device is shown, and as shown in FIG. 3, the phases indicated by U, V, W are divided into three in the circumferential direction.

  As shown in FIG. 3, one movable contact 12 is attached to each phase of the current collecting ring 54. A hemispherical contactor 64 is provided at the tip of the movable contact 12. The movable contact 12 rotates with the rotation of the current collecting ring 54, and an energization circuit is formed by contacting either one of the two switching contacts 11 provided. The switching contact 11 is fixed to the insulating ring 74. The switching contact inside the tap selector 2 has the same configuration.

  A structural feature of the first embodiment resides in the switching contact 11. That is, as shown in FIG. 1, the movable contact 11 is provided with a silver plating layer 22 over the entire surface of the plate-shaped contact base material 21. Further, a hard carbon coating layer 23 such as diamond-like carbon is applied to the entire outside of the silver plating layer 22. Among these, the thickness of the silver plating layer 22 is formed in 5-50 micrometers, and the hardness is comprised so that it may become Vickers hardness 90 or more. On the other hand, the hard carbon coating layer 23 is formed to have a thickness of 0.1 to 4 μm and a Vickers hardness of 1000 or more.

[Operation of tap changer during load]
Next, the operation of the on-load tap switching device in the present embodiment configured as described above will be described. That is, the driving force of an operating mechanism (not shown) is transmitted from the speed reducer 5 to the energy storage device 6 via the drive shaft 7. For this reason, the cam 9 rotates by the driving force of the energy storage device 6, and the electric circuit of the contact portion 8 is switched. The tap selector 2 is also driven by the operation mechanism in the same manner as the switching switch 1 to select a tap.

[Function and effect]
Next, the effect of the switching contact 11 that is a feature of the present embodiment will be described. The movable contact 12 rotates in accordance with the rotation of the cam 9 and the current collecting ring 54 and comes into contact with one of the two switching contacts 11 provided for each phase to constitute an energization circuit. Here, since the silver plating layer 22 is given to the switching contact 11, and the hard carbon film layer 23 is further given to the outer side, the switching contact 11 and the movable contact 12 come into contact and slide. At this time, the hard carbon coating layer 23 has a low friction and a high hardness and a low resistance. Therefore, good sliding characteristics can be obtained with the switching contact 11 and the wear amount of the hard carbon coating layer 23 is small, so that a long life can be obtained.

  Moreover, since the hard carbon coating layer 23 is excellent in corrosion resistance, it is possible to suppress the formation of silver sulfide by the reaction between the silver plating layer 22 applied to the switching contact 11 and the insulating oil. In addition, since the hard carbon coating layer 23 is very hard, when it peels, the silver plating layer 22 side will fracture | rupture, but in this embodiment, the inner silver plating layer 22 shall be Vickers hardness 90 or more, The thickness is increased to 5-50 μm and the thickness of the outer hard carbon coating layer 23 is decreased to 0.1-4 μm, so even if vibration or shear force acting during sliding is applied, silver plating is applied. Breakage on the layer 22 side can be avoided, and the hard carbon coating layer 23 does not peel from the silver plating layer 22.

  As described above, according to the present embodiment, the silver plating layer 22 is applied to the switching contact 11 of the on-load tap switching device, and the hard carbon coating layer 23 such as diamond-like carbon is formed outside the silver plating layer 22. As a result, it is possible to obtain a long-life switching contact 11 having good sliding characteristics with small frictional force and wear during switching operation.

  Furthermore, by applying the hard carbon coating layer 23, it is possible to suppress the formation of silver sulfide due to the reaction between the silver plating layer 22 and the insulating oil in the on-load tap switching device. In addition, the thickness of the silver plating layer 22 is 5 to 50 μm, the thickness of the hard carbon coating layer 23 is 0.1 to 4 μm, and the hardness of the silver plating layer 22 is configured to have a Vickers hardness of 90 or more. Further, it is possible to reliably prevent the hard carbon coating layer 23 from peeling off. As a result, a highly reliable on-load tap changer with a small and simple configuration can be provided.

(2) Second Embodiment [Configuration]
The second embodiment will be described with reference to FIGS. 4 and 5. The structural feature of the second embodiment resides in the switching contact 11b, and the on-load tap switching device in which the switching contact 11b is incorporated is the same as that shown in FIGS. Description is omitted. 4 is a plan view of the switching contact 11b, and FIG. 5 is a sectional view of the same.

  As shown in FIGS. 4 and 5, the movable contact 11b is provided with a silver plating layer 22b on the entire surface of the plate-shaped contact base material 21b, and diamond-like carbon or the like is formed on a part of the outside of the silver plating layer 22b. The hard carbon coating layer 23b is applied. The range in which the hard carbon coating layer 23b is not applied on the surface of the silver plating layer 22b is a range in contact with the movable contact 12 configured in the same manner as in the first embodiment.

[Function and effect]
The second embodiment having the above configuration has the following unique operational effects in addition to the operational effects of the first embodiment, that is, the improvement of sliding characteristics and long life. That is, the hard carbon coating layer 23b is not applied to the portion in contact with the movable contact 12 on the surface of the silver plating layer 22b, and the movable contact 12 and the silver plating layer 22b are in contact with each other. Therefore, it is possible to ensure good current-carrying performance, and at the same time, it is possible to reduce the portion for applying the expensive hard carbon coating layer 23b, and it is more economical.

(3) Third Embodiment [Configuration]
Next, a third embodiment of the on-load tap switching device according to the present invention will be described. The structural feature of the third embodiment resides in the switching contact 11c, and the on-load tap switching device in which the switching contact 11c is incorporated is the same as that shown in FIGS. Description is omitted. FIG. 6 is a sectional view of the switching contact 11c.

  As shown in FIG. 6, in the third embodiment, the switching contact 11c is formed by applying only a hard carbon coating layer 23c such as diamond-like carbon on the surface of the plate-shaped contact base material 21c without applying a silver plating layer. It is characterized in that it is.

[Function and effect]
In 3rd Embodiment which has the above structure, the effect by the hard carbon film 23c can be acquired. That is, the hard carbon coating 23c is applied to the entire surface of the switching contact 11c, so that when the switching contact 11c and the movable contact 12 slide in contact, the low friction and high hardness characteristics of the hard carbon coating 23c. In addition, good sliding characteristics can be obtained with a low resistance and a small amount of wear, resulting in a long life. Moreover, since the hard carbon film 23c is excellent in corrosion resistance, corrosion due to long-term use of the switching contact 11c can be suppressed.

(4) Fourth Embodiment [Configuration]
Then, an example of embodiment regarding the manufacturing apparatus of the switching contact for on-load tap switching devices concerning the present invention is described using FIG. 7, FIG. FIG. 7 is a cross-sectional view of an apparatus for manufacturing a switching contact for an on-load tap switching device according to this embodiment, and FIG. 8 is a cross-sectional view of the manufacturing device of this embodiment.

  As shown in FIGS. 7 and 8, the manufacturing apparatus 30 is an apparatus for applying a hard carbon coating 23d to the switching contacts 11d for a plurality of on-load tap switching devices. The switching contact 11d is already provided with a silver plating layer 22d. The manufacturing apparatus 30 is provided with a base 32 on which a plurality of switching contacts 11d are simultaneously mounted, and a cover 31 that covers a portion other than the hard carbon coating layer 23d in the switching contacts 11d.

  In such a manufacturing apparatus 30, the switching contact 11 d is sandwiched between the cover 31 and the base 32. Furthermore, a pressure spring 33 and a fastening tool 34 that apply pressure to the cover 31 are attached to the cover 31, and a lid 35 is installed above the pressure spring 33 and the fastening tool 34. In addition, as a method for applying the hard carbon film 23d, a vapor deposition method, a sputtering method, and the like are known, but the method is not limited in this embodiment.

[Function and effect]
By using the manufacturing device 30 for the switching contact 11d in the present embodiment configured as described above, all the switching contacts 11d are hardened together with a plurality of the switching contacts 11d attached to the manufacturing device 30. A carbon coating 23d can be applied. Therefore, the switching contact 11d can be manufactured efficiently and the economy is improved.

(5) Other Embodiments The present invention is not limited to the above embodiment, and the shape and number of switching contacts, the shape and dimensions of the silver plating layer and the hard carbon coating layer, and the like can be changed as appropriate. Of course, various modifications can be made according to the application of the on-load tap switching device. For example, the above embodiment can be applied to the switching contact in the tap selector of the on-load tap switching device.

Sectional drawing of the tap switching apparatus at the time of 1st Embodiment which concerns on this invention. The plane sectional view of the switching contact portion in the tap change device at the time of loading of a 1st embodiment. Sectional drawing of the switching contact in 1st Embodiment. The top view of the switching contact in 2nd Embodiment which concerns on this invention. Sectional drawing of the switching contact in 2nd Embodiment. Sectional drawing of the switching contact in 3rd Embodiment which concerns on this invention. The top view of 4th Embodiment which concerns on this invention. Sectional drawing of 4th Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Switching switch 2 ... Tap selector 3 ... Current limiting resistor 4 ... Transformer main body tank 5 ... Reduction gear 6 ... Energy storage device 6b ... Energy storage spring 7 ... Drive shaft 8 ... Contact part 9 ... Cam 10 ... Vacuum Valve 11, 11b, 11c, 11d ... Switching contact 12 ... Movable contact 54 ... Current collecting ring 64 ... Contact 74 ... Insulating ring 21, 21b, 21c, 21d ... Contact base material 22, 22b, 22d ... Silver plating layer 23, 23b, 23c ... Hard carbon coating layer 30 ... Switching contact manufacturing device 31 for on-load tap switching device ... Cover 32 ... Base 33 ... Pressure spring 34 ... Fastening tool 35 ... Lid

Claims (7)

In the load tap switching device provided with a switching contact comprising a switching switch and a tap selector, wherein the switching contact and the tap selector constitute an energizing circuit,
The switching contact is provided with a silver plating layer,
An on-load tap switching device, wherein the silver plating layer is provided with a hard carbon coating layer. The silver plating layer is applied to the entire surface of the switching contact,
The on-load tap switching device according to claim 1, wherein the hard carbon coating layer is partially applied to a surface of the silver plating layer. The silver plating layer is formed to a thickness of 5 μm or more,
The on-load tap switching device according to claim 1 or 2, wherein the hard carbon coating layer is formed to have a thickness of 4 µm or less.   The on-load tap switching device according to any one of claims 1 to 3, wherein the silver plating layer has a Vickers hardness of 90 or more. In the load tap switching device provided with a switching contact comprising a switching switch and a tap selector, wherein the switching contact and the tap selector constitute an energizing circuit,
An on-load tap switching device, wherein the switching contact is provided with a hard carbon coating layer. A switching contact for a load tap switching device provided in a switching switch and a tap selector of the load tap switching device,
Silver plating layer is given,
A switching contact for an on-load tap switching device, wherein the silver plating layer is provided with a hard carbon coating layer. A device for manufacturing a switching contact for a tap switching device at the time of loading according to claim 6,
A base for simultaneously mounting a plurality of the switching contacts;
An apparatus for manufacturing a switching contact for an on-load tap switching device, comprising a cover that covers a portion of the switching contact other than the hard carbon coating layer.

Images