JPS6346711A - On-load tap changing transformer - Google Patents

Abstract

PURPOSE:To prevent the scattering of metallic powder, and to obviate the generation of the accident of breakdown by covering fixed and movable contacts for a tap selector with a cylinder with a bottom in a tank and circulating an insulating medium in the cylinder into the tank through a piping and a filter. CONSTITUTION:Since metallic powder generated from a tap selector 3d scatters in an insulating gas first but it is surrounded by a cylinder 7, scattering toward the transformer content 2 side is prevented, and metallic powder collects on a bottom 8. When an air blower 10 is operated periodically after the number of tap changing reaches a fixed value, the insulating gas 4 in the cylinder 7 is sucked from an inlet port 13, and blown against the tap selector 3d from a blow-off port 14 through a piping 9. Consequently, metallic powder is sucked into the piping 9 from the inlet port 13, and the greater part of metallic powder are collected by a filter 11 while the cleaned insulating gas 4 is blown against the tap selector 3d in the cylinder 7 from the blow-off port 14 again. Accordingly, metallic powder is captured quickly by the filter 11 without scattering in a tank 1.

Description

[Detailed Description of the Invention] [Object of the Invention] (Field of Industrial Application) The present invention relates to an on-load tap-changer transformer in which an on-load tap-changer is housed together with the contents of the transformer in the same tank. The present invention relates to an on-load tap-changing transformer suitable for a gas-insulated transformer that has an improved structure for collecting metal powder generated from the on-load tap-changing device.

(Prior Art) In recent years, as the demand for electricity has increased, there has been an increasing demand for the supply of high-quality electricity. The supply of high-quality power includes stable power supply, such as no temporary interruption of power supply such as power outages, and little voltage fluctuation of the supplied power. The supplied power must change its voltage as the load changes. For example, when the load is heavy, it is necessary to change the output voltage of the transformer in response to changes in the load, such as increasing the output voltage of the transformer. One way to change this output voltage is to change the number of turns in the transformer winding by switching the taps installed on the transformer winding in a live state using an on-load tap changer, as is well known. I am trying to adjust the output voltage.

The structure of a conventional on-load tap-changing transformer equipped with such an on-load tap changer is roughly as follows. In other words, the contents of the transformer consisting of the iron core, windings, etc. are stored in a tank together with an insulating medium such as insulating oil and gas, and the switching switch of the on-load tap changer is surrounded by an insulating tube inside the tank. A tap selector is suspended above the tank and further below this insulating cylinder. The tap selector has a plurality of fixed contacts arranged in an annular shape and each connected to a tap winding of a transformer, and is attached to an operating shaft rotatably provided in the center of the fixed contacts. The movable contacts are connected to the tap selector and are suspended below the tap selector via a support.

To adjust the output voltage of the transformer using such a load tap changer, an electric operating mechanism provided outside the tank rotates the operating shaft via a transmission shaft, gear mechanism, etc. The taps are switched by fixing the switch and tap selector and switching the movable contacts according to a predetermined sequence.

(Problem to be Solved by the Invention) However, when the on-load tap changer repeatedly performs switching operations in this way, the fixed contact and movable contact of the tap selector gradually wear out, and metal powder is released from there. It is generated and scattered into the insulating medium inside the tank. Inside the transformer tank, the high voltage inside the transformer is shared between various insulators. Therefore, if metal powder is scattered in the insulating medium, the voltage distribution of the insulator changes, and there is a possibility that corona generation or short circuit accidents may occur. In particular, gas-insulated transformers, which are installed in underground substations in buildings and underground malls due to the overcrowding of cities in recent years and are highly safe against fire, generate more metal powder than oil-immersed transformers. If mixed into an insulating gas such as SF6, the dielectric strength will be significantly reduced and there is a risk of dielectric breakdown.

In order to prevent such dielectric breakdown accidents caused by the scattering of metal powder, insulators have been placed in the tank to separate the tap changer from the transformer contents, as shown in Japanese Patent Laid-Open No. 57-114214. A method of providing a partition plate has been considered. However, even if such a partition plate is provided, metal powder will be somewhat difficult to scatter to the inside of the transformer, but it will accumulate on live parts and tap leads on the load tap changer side, causing an insulation breakdown accident. It is difficult to prevent it completely. It is still difficult to completely prevent metal powder from scattering using partition plates, and there is still the risk of insulation breakdown occurring inside the transformer.

On the other hand, as another means, as shown in Japanese Unexamined Patent Publication No. 57-76815, it has been proposed to provide a tray below the tap selector to collect metal powder. However, a considerable amount of the metal powder collected on the receiver plate will accumulate after long-term operation of the transformer, and there is a possibility that it will be re-dispersed into the surrounding area over time. This has a negative effect on insulation. Therefore, in order to prevent this, it is necessary to periodically stop the operation of the transformer and collect the metal powder, which causes troublesome maintenance work and impedes the stable supply of electric power.

In view of the above points, the present invention prevents the scattering of metal powder generated from the tap changer during load, reliably collects the metal powder, prevents the occurrence of insulation breakdown accidents, has high insulation reliability, and is easy to maintain. The purpose of the present invention is to obtain an easy-to-use on-load tap-changing transformer.

[Structure of the Invention] (Means for Solving the Problem) In order to achieve the above object, the present invention provides an on-load tap in which the contents of a transformer and an on-load tap changer are housed together with an insulating medium in the same tank. A switching transformer in which at least the fixed and movable contacts of the tap selector are covered with a bottomed cylinder in the tank, and the insulating medium in the cylinder is circulated into the tank via piping and a filter. It is.

(Function) The circulated insulating medium is blown onto the tap selector from the blowing port of the tube, and the metal powder generated from the tap selector is sucked into the suction port and captured by the filter installed in the middle of the piping. This prevents metal powder from scattering. Also, by checking the amount of metal powder collected by the filter, the lifespan of the fixed tab selector and the movable contact is determined.

(Example) Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

In FIGS. 1 and 2, reference numeral 1 denotes a transformer tank that houses the transformer contents 1 consisting of an iron core 2 and 2 windings 2b and an on-load tap changer 1 together with an insulating gas 4 such as SF6. The on-load tap changer 1 has a switching switch 3& suspended on the top surface of the tank 1, and a fixed and movable contact 3 suspended below the switching switch 3a via a support or the like.
It is composed of a tap selector 3d equipped with taps b and 3c.

5 is an operating shaft of the movable contactor 3C, and 6 is a tap lead connecting the tap winding of the transformer and the fixed contactor 3b of the tap selector 3d.

The tap selector 3d configured in this manner is surrounded by a bottomed cylinder 7 made of an insulating material, and the bottom 8 of the cylinder 7 has a gentle inverted conical shape that slopes downward toward the center. is formed. The upper part of this cylinder 7 and the center part of the bottom 8 are connected by a pipe 9, and this pipe 9 is pulled out to the outside of the tank 1, and a blower is installed on the way to circulate the insulating gas 4 inside the cylinder 7. 10 and a filter 11 for collecting metal powder are provided. Furthermore, on the upstream side of this piping 9,
Downstream side and between blower 10 and filter 11/J Lube 1
2 a r 12 b r 12 c are provided respectively. Therefore, the lower side of the pipe 9 serves as a suction port 13, and the upper side serves as a blowing port I4.

According to the on-load tap-changing transformer configured in this way, the metal powder generated from the tap selector 3d of the on-load tap changer initially scatters in the insulating gas, but since it is surrounded by the tube 7, the transformation occurs. Splashing towards the l contents of the container is prevented and most of it accumulates in the bottom 8. When the number of tap switching reaches a certain value, when the blower IQ is operated periodically, the insulating gas 4 in the cylinder 7 is sucked from the suction port 13, passes through the pipe 9, and is blown from the blowing port 14 toward the tap selector 3d. It will be done. Further, the blower IQ may be operated continuously at all times. By spraying the insulating gas 4, the metal powder that is being scattered and accumulated on the bottom 8 is sucked into the pipe 9 through the suction port 13. Most of the sucked metal powder is collected by the filter 11, and the cleaned insulating gas 4 is again blown through the blowing port 14 toward the tap selector 3d in the cylinder 7, and this process is repeated. By returning υ, the metal powder is quickly collected in the filter 11 without scattering into the tank 1. When the number of switching times of the tap changer during load reaches a certain value, the blower 10
The operation of the filter 11 is stopped, the valves 12b and 12c are closed, and the filter 11 is replaced. In addition, by investigating the amount of metal powder collected by the filter 11 at this time, it is possible to fix the switch selector 3d and determine the lifespan of the movable contact 3b r J c, thereby preventing abnormal switching operation due to contact deterioration. can be prevented from occurring. Furthermore, if the filter 11 is provided with an inspection window etc. that can be easily viewed from the outside, the filter 11
The amount of metal powder can be constantly checked without removing the metal powder, making maintenance even easier.

The figure shows another embodiment of the present invention, in which a fixed contact 3C of a tap selector 3d is fixed to a tube 7. In this way, the fixed contact 3c and the tap lead 6 are connected. becomes easier.

Although the above embodiments have been described using a gas insulated transformer as an example, the insulating medium is not limited to insulating gas, and the same effect can be obtained even if insulating oil is used.

[Effects of the Invention] As described above, according to the present invention, in the case where the contents of a transformer and an on-load tap changer consisting of a switching switch and a tap selector are housed together with an insulating medium in the same tank, Inside the tank, at least the fixed and movable contact of the tap selector is covered with a cylinder with a bottom, and the insulating medium in this cylinder is circulated in the tank by a blower via piping and a filter, and is blown onto the tap selector to filter it. Since the metal powder is collected by using the method, it prevents the metal powder from scattering, reliably collects the metal powder, and prevents the occurrence of dielectric breakdown accidents.
It is possible to obtain an on-load tap change transformer that has high insulation reliability and is easy to maintain.

[Brief explanation of the drawing]

FIG. 1 is a side view showing an on-load tap changer according to an embodiment of the present invention, FIG. 2 is an enlarged side view of the on-load tap changer of FIG. 1, and FIG. It is a side view showing an example. 1...tank, l...transformer contents, dan...load tap changer, 3a...switching switch, 3b, 3c...
・Fixed. Movable contact, 3d...Tap selector, 4...Insulating gas, 7...Cylinder, 8...Bottom, 9...Piping, 10...
・Blower, 11...Filter, 12mr12b, 1
2c... Valve, 13... Suction port, 14... Spray port.

Claims (3)

[Claims] (1) In an on-load tap-changing transformer in which the contents of the transformer and an on-load tap changer consisting of a switching switch and a tap selector are housed together with an insulating medium in the same tank, at least one tap is selected in the tank. A load characterized in that the fixing device and the movable contact are covered with a cylinder with a bottom, and the insulating medium inside the cylinder is circulated through piping and a filter into the tank by a blower and blown onto the tap selector. Time tap changing transformer. (2) The on-load tap changing transformer according to claim 1, wherein the tap selector is surrounded by a cylinder with a bottom. (3) The on-load tap changing transformer according to claim 1, wherein the fixed contact of the tap selector is attached to a bottomed cylinder.