JPH09162041A - Gas-insulated transformer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify an on-load tap changeover device, by adapting it to the differential pressure between the enclosures for integrating respectively its diverter switch and the tap selector thereinto and its electric specifications. SOLUTION: Separating a diverter switch 2 of an on-load tap changeover device and its tap selector 4 from each other, the diverter switch 2 and the tap selector 4 are stored respectively in enclosures 3, 5 with different filled-gas pressures from each other. Further, a partition 1 for sealing in pressure the joint of the enclosure 3 to the enclosure 5 is provided to dispose therein an insulation spacer with a plurality of throughly arranged conductors 13 whereinto lead wires 12 for connecting the diverter switch 2 with the tap selector 4 are inserted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas-insulated transformer with a load tap changer that adjusts a voltage according to a load without interrupting energization.

[0002]

2. Description of the Related Art In recent years, substations installed in urban areas are equipped with a gas-insulated transformer or switchgear that does not use flammable insulating oil from the viewpoint of disaster prevention (fire prevention). Is moving to a substation.

On the other hand, the demand for electricity in urban areas has increased significantly,
Large-capacity substations are also required to be installed in the districts where buildings and houses are densely populated, so the number of cases where they are installed in the underground space of buildings is increasing. Naturally, there is a strong demand for stable power quality represented by voltage and frequency.

In order to stabilize the power quality, it is necessary to use a load tap changer that changes the voltage of the transformer without interrupting the current supply and adjusts the voltage according to the load. Mostly equipped in oil-filled transformers.

Even if a gas-insulated transformer is installed in a new substation in response to an increase in power demand, the voltage is 25
7kV ~ 500kV, capacity 300MVA ~ 1500M
It is assumed that VA and a large-capacity device equal to or higher than the conventional one will be used. With the increase in capacity, it is not possible to increase the volume of the transformer due to transportation restrictions such as in city blocks and volume compression of the building basement.

Compared with an oil-filled transformer that uses insulating oil, the gas-insulated transformer uses a gas body such as SF ₆ gas for insulation and cooling, so that the heat capacity that affects the cooling function is about 1/200. turn into. Therefore, in gas-insulated transformers, the gas pressure is often increased to about 4 to 6 kgf / cm ^{2 in} order to supplement the reduction in heat capacity and improve the insulation function.

[0007] On the other hand, the load tap changer used in the gas insulated transformer uses a vacuum (shutoff) valve at its contact to improve the shutoff performance in gas. This vacuum valve opens and closes the contacts provided in the vacuum by utilizing the expansion and contraction of the metal bellows while keeping the inside vacuum.

Due to the operation and life of the metal bellows, it is not preferable that the gas pressure in the transformer, which is the atmosphere of the vacuum valve, becomes 4 to 6 kgf / cm ² . Therefore, among the components of the tap changer under load, the diverter switch to which the vacuum valve is attached and the tap selector are separated, and these are housed in different containers, and the gas pressure of each is matched to the built-in mechanism. It is considered to set the pressure.

Specifically, it is assumed that the diverter switch built-in container has a gas pressure of 0.2 to 0.5 kgf / cm ² and the tap selector built-in container has a gas pressure of 4 to 6 kgf / cm ² .
The two containers are electrically connected by seven lead wires (in the case of a three-phase load tap changer), and mechanically an electric operation mechanism and a driving shaft structure for driving both in synchronization. Section is provided.

The driving shaft structure may be connected in series in the atmosphere, but the seven lead wires are in the gas between the two containers in order to avoid exposure of the charging section to the atmosphere and simplify the process. It is preferable to pass the material that serves as the pressure partition wall of both containers.

[0011]

The load tap changer of the gas insulation transformer has a tap selector connected to the tap lead wire from the tap coil, and generally has 12 to 18 leads corresponding to one. The wires are connected for three phases,
Naturally, higher gas pressure is preferable for insulation and cooling.

On the other hand, on the side of the diverter switch having a vacuum valve, it is desirable to limit the gas pressure to 0.2 to 0.5 kgf / cm ² . If the transformer side with tap coil is 4
When holding the gas pressure ~6kgf / cm ^2, when the pressure difference between them also consider to vacuum process during maintenance and inspection of the diverter switch side, it is necessary to withstand a differential pressure of up to 7 kgf / cm ^2.

The seven lead wires passing through the pressure bulkhead carry a current of about 600 to 900 A, and the insulation voltage to ground is equivalent to 100 (230 kV), which is the neutral point voltage of the transformer. Is one tap, which is equivalent to 2 to 3 kV.

The present invention has been made in consideration of the above-mentioned circumstances, and is provided with a tap changer under load which is simplified in conformity with the differential pressure between the diverter switch container and the tap selector container and electrical specifications. An object is to provide a gas-insulated transformer.

[0015]

In order to solve the above-mentioned problems, claim 1 of the present invention separates a diverter switch and a tap selector of a load tap changer, and these diverter switch and tap selector are separated from each other. Each of them is housed in a container having a different enclosed gas pressure, and a partition wall is provided for pressure-sealing these containers, and a plurality of conductors, through which lead wires connecting the diverter switch and the tap selector are inserted, are arranged in this partition wall. It is characterized in that an insulating spacer is provided.

According to a second aspect of the present invention, in the insulating spacer according to the first aspect, a plurality of insulating spacers are provided with a predetermined interval in the conductor axial direction.

[0017]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing an embodiment of a gas insulation transformer according to the present invention, and FIG. 2 is a view in the direction of the arrow X in FIG. In FIG. 1, an insulating partition wall 1 with multiple conductors
Is arranged in the axial middle of a gas-filled connection duct 6 formed between a container 3 accommodating a diverter switch 2 of a load tap changer and a container 5 accommodating a tap selector 4, and the container 3, 5 is pressure-sealed.

The diverter switch 2 and the tap selector 4 are driven by being operatively connected to the electric operating mechanism 10 via driving shafts 7, 8 and 9, respectively. A tap lead wire 11 wired from a tap coil of a transformer is connected to the tap selector 4, and the tap lead wire 11 and the tap selector 4 are in the atmosphere of the same gas pressure of 4 to 6 kgf / cm ² .

Further, between the diverter switch 2 and the tap selector 4 in the case of a three-phase transformer, seven connecting lead wires 12 are required, and these connecting lead wires 12 are connected from the container 5 to the insulating partition wall 1. Pressure-sealed two-core conductor 13
A gas pressure of 0.2 to 0.5 kgf / cm ² is inserted through and connected to the sealed container 3.

FIG. 3 is an enlarged view showing the two-core conductor 13 of the insulating partition wall 1 in FIG. 1, and FIG. 4 is a view in the Y direction of FIG.
In FIG. 3, conductor attachment electrodes 15 are embedded in four places in an insulator 14 as an insulating spacer of the insulating partition 1. The conductor attachment electrode 15 is provided with a hole through which the central conductor 13a penetrates, and the central conductor 13a has an insulator 1 formed therein.
6 is attached closely. The insulator 16 electrically insulates the center conductor 13 a from the conductor mounting electrode 15.

On the outer peripheral side of the center conductor 13a, a cylindrical conductor 17 serving as the other current-carrying conductor is provided.
It is fixed by tightening the tightening bolts 19a and 19b through the tightening metal fitting 18. The tubular conductor 17 is
The shape of the charging portion side is improved with respect to the voltage applied between the gas-containing connecting duct 6 and the conductor mounting electrode 15, and the expansion of the inner diameter of the gas-containing connecting duct 6 is suppressed.

The current path passes through the cylindrical conductor 17 → the conductor mounting electrode 15 → the cylindrical conductor 17, and one conductor mounting electrode 15 constitutes a two-circuit current path. Therefore, if four conductor mounting electrodes 15 are embedded in the insulating partition wall 1, a current path of eight circuits can be obtained. Therefore, one insulating partition wall requires seven conductor current paths. Can be configured.

In the present embodiment, the insulation barrier voltage to ground, which is a necessary function of the insulating partition wall 1, is equivalent to 100 (230 kV), while the insulation voltage between terminals is as low as about 2 to 3 kV. Is.

Next, the operation of this embodiment will be described.

As described above, the diverter switch 2 and the tap selector 4 of the load tap changer are separately configured, and the diverter switch 2 and the tap selector 4 are housed in the containers 3 and 5 having different sealed gas pressures. An insulating partition wall 1 for pressure-sealing these containers 3 and 5 is provided, and the diverter switch 2 is attached to the insulating partition wall 1.
By providing the insulator 14 in which a plurality of two-core conductors 13 through which the connecting lead wires 12 that connect between the tap selector 4 and the tap selector 4 are arranged are provided, the insulating partition wall 1 having a plurality of lead-throughs can be formed in the minimum size. Therefore, the connection structure of the container 3 and the container 5 of the load tap changer can be downsized and simplified, and the installation space can be reduced.

On the other hand, the gas-insulated bus bar and the gas switchgear include
Many insulating barriers have been used conventionally, their withstand voltage characteristics are stable, and their withstand pressure strength has been sufficiently confirmed. An application example using such an insulating partition is shown in FIGS. 5 (A) and 5 (B). Note that the same or corresponding portions as those of the above-described embodiment will be described using the same reference numerals.

As shown in FIGS. 5 (A) and 5 (B), the insulating partition 1 is basically of a three-conductor type and can cover three phases. It is easy to provide the conductor mounting electrode 15 having the same shape as that of the above-described embodiment on the conductor unattached portion 21 of the three-conductor insulating partition 1 to which the single core conductor 20 is not attached.

As described above, according to the application example, it is possible to construct an insulating partition with a multi-conductor of 7 conductors having the same duct diameter as that of a 3-conductor insulating partition that withstands the insulation class 100 of the conventional gas switchgear. it can.

The present invention is not limited to the above embodiment, and various modifications can be made. For example, in the above-described embodiment, one insulator 14 as an insulating spacer is arranged in the insulating partition wall 1, but the present invention is not limited to this, and a plurality of insulators 14 may be provided at a predetermined interval in the conductor axial direction. Good. With this configuration, the sealing effect and strength of the insulator 14 can be enhanced, and the insulation strength can also be enhanced.

[0031]

As described above, according to the first aspect of the present invention,
According to the method, the diverter switch and the tap selector of the load tap changer are separated, and the diverter switch and the tap selector are respectively housed in containers having different sealed gas pressures, and a partition wall for pressure-sealing between these containers is provided. , By providing an insulating spacer in which a plurality of conductors through which lead wires connecting between the diverter switch and the tap selector are inserted are provided in this partition wall, an insulating partition wall having a plurality of lead-throughs can be formed in a minimum size. , The connection structure between the container of the diverter switch and the container of the tap selector of the tap changer for high-voltage / large-capacity load can be downsized and simplified, and the installation space can be reduced.

According to claim 2, the insulating spacer according to claim 1 has a plurality of insulating spacers provided at a predetermined interval in the axial direction of the conductor. It is possible to enhance the sealing effect and the strength of, as well as the insulation strength.

[Brief description of the drawings]

FIG. 1 is a cross-sectional configuration diagram showing an embodiment of a gas insulation transformer according to the present invention.

FIG. 2 is a view on arrow in the X direction in FIG.

FIG. 3 is an enlarged view showing a two-core conductor of the insulating partition in FIG.

FIG. 4 is a view in the Y direction of FIG.

5 (A) and 5 (B) are a main part configuration diagram and a front view showing an application example of an embodiment of a gas insulation transformer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Insulation bulkhead 2 Diverter switch 3 Container 4 Tap selector 5 Container 6 Gas connection duct 7,8,9 Driving shaft 10 Electric operation mechanism 11 Tap lead wire 12 Connection lead wire 13 2-core conductor 13a Center conductor 14 Insulator (insulating spacer) ) 15 conductor mounting electrode 16 insulator 17 tubular conductor 18 tightening metal fittings 19a, 19b tightening bolt 20 single core conductor 21 conductor unattached part

Claims (2)

[Claims] 1. A diverter switch and a tap selector of a load tap changer are separated from each other, and the diverter switch and the tap selector are respectively housed in containers having different sealed gas pressures, and a partition wall for pressure sealing between these containers is provided. A gas-insulated transformer, wherein the partition wall is provided with an insulating spacer in which a plurality of conductors through which lead wires connecting the diverter switch and the tap selector are inserted are arranged. 2. The gas insulated transformer according to claim 1, wherein the insulating spacer is provided with a plurality of insulating spacers having a predetermined interval in the axial direction of the conductor.