JPH0654619B2 - Gas insulated bushing - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a gas-insulated switchgear, and more particularly to a capacitor-type gas-insulated bushing.

[Technical background of the invention and its problems] Conventionally, as a surge voltage divider for a fault point locating device for a transmission line or an instrument transformer for detecting a main circuit AC voltage, an oil-filled capacitor type instrument transformer (hereinafter Oil-filled PD) or oil-immersed paper capacitor bushing (hereinafter oil-filled Bg)
Has been used. This oil-filled PD has an oil-filled condenser housed in an insulator tube, and there is a risk of causing a ground fault accident due to salt damage or flying objects. Further, since the circuit breaker, the disconnecting switch, etc. are separately installed and the necessary insulation distance must be secured, a large installation space is required, and a large concrete foundation cost for installing these devices is also required. This will be described with reference to FIGS.

Fig. 3 is a single-line connection diagram of the transmission line lead-in part of the power plant and substation, where 1 is a transformer for capacitor type instrument, 2 is a line side grounding switch, 3 is a disconnecting switch, 4 is a working grounding switch, 5a Is a current transformer, 6 is a circuit breaker, 5b is a second current transformer, and 7a and 7b are busbar switching disconnectors. As shown in FIG. 4, the capacitor-type meter transformer 1 comprises a main capacitor 10, a voltage dividing capacitor 11 and a leakage transformer 12 connected in series to the main capacitor 10. In addition, a surge voltage divider for fault point locator for transmission line
13 may be attached. Reference numeral 14 is a transformer box containing 11 to 13. As described above, the capacitor type instrument transformer 1 is used as an instrument transformer for measuring an AC voltage of a transmission line and a voltage divider for detecting a surge when a lightning surge enters. Oil filled PDs or oil filled Bg have been commonly used to meet these applications. It is difficult to detect such an oil-filled product in an enclosed SF ₆ gas-insulated switchgear in case of oil leak, and it is difficult to detect if oil leaks into the insulating gas. There is also the possibility of a fire accident. Therefore, in general, as shown in FIG.
Has been adopted separately, or a method of attaching the oil-filled Bg or oil-filled PD to the gas-insulated switchgear on the premise that the inspection and maintenance are sufficiently performed in view of the risk of oil leakage. In the figure, symbols 1 to 7 indicate the same devices as those in FIG. 3, and 8a and 8b bushings.
Reference numeral 9 is an SF ₆ gas-insulated switchgear composed of 2 to 8 devices. FIG. 6 is an explanatory view of the internal structure of the gas-insulated switchgear 9, which is composed of insulating spacers 15a and 15b for supporting the conductors from the bushing 8a to the disconnector 3 and a breaker 6.

As described above, when the oil-filled PD is placed separately, there is a risk of accidents due to salt damage and flying objects, which is disadvantageous in terms of installation space, concrete foundation cost, and the like. Further, when the oil-filled PD or the oil-filled Bg is attached to the gas-insulated switchgear, there is a risk of oil leaking into the SF ₆ gas, which requires a great deal of labor for inspection and maintenance.

[Object of the Invention] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a large-current capacitor-type gas-insulated bushing that does not use oil.

[Summary of the Invention] In order to achieve the above object, in the present invention, an electrode foil on the ground side of a capacitor cone, which is provided outside a central conductor and forms a main capacitor of a transformer, is connected to an external lead terminal. Since the transformation device is connected to the external lead-out terminal, it is possible to provide a gas-insulated bushing that performs a part of the transformation function without fear of oil leakage.

[Embodiment of the Invention] An embodiment of the gas-insulated bushing of the gas-insulated switchgear of the invention will be described below with reference to FIG. FIG. 1 is an internal structure diagram of the bushing 8a of FIG. 6, and 16 is a dry condenser cone, which corresponds to the condenser 10 of FIG. Reference numeral 14 is a transformer box, which is a voltage dividing capacitor 11 and a leakage transformer shown in FIG.
12, Surge voltage divider 13, etc. are stored. As the dry type capacitor, an electrode made of aluminum foil or scrap metal, and a dielectric material made of paper and epoxy resin can be used. Conical condenser cone with external shape
The hollow tube 16 is coaxially arranged so as not to be in contact with the central conductor 23 for conducting electricity, and is provided in the insulator tube 8c for enclosing the insulating gas.

A bushing 8a is attached above the tank of the disconnector 3, and a condenser tank is provided at the end. The condenser cone 16 is electrically connected between the bushing 8a and the disconnector 3.

Reference numeral 18 is a conductor for drawing out the potential of the electrode foil 17 on the ground side of the condenser cone to the outside, which is connected to the external extraction terminal 19 in the state where the high pressure gas in the bushing is sealed, and further connected to the transformer box 14. . Reference numeral 20 is a shield, which prevents the withstand voltage performance from being deteriorated by protrusions such as the flange 21 and the lead terminal 19. Reference numeral 22 denotes a connection electrode, which connects the center conductor 23 and the upper end of the condenser cone 16 and is fixed by bolt fastening or the like. Reference numeral 24 is a flexible connection structure that can absorb thermal expansion and contraction of the conductor due to temperature rise at the connecting portion between the bushing upper plate conductor 25 and the central conductor 23, and dimensional deviation due to manufacturing errors. Reference numeral 26 is a connection portion under the bushing conductor, which also has a flexible connection structure. Connection electrode
The central conductor 23 near 22 is provided with a vent hole 27a at a position where gas in the condenser cone can be vented, and a vent hole 27b for letting out this gas is provided above the conductor. Further, the flange 21 is provided with a vent hole 27c for circulating the cooled gas from the outer peripheral portion of the condenser cone to the lower portion.

In the present embodiment, an external lead terminal 19 is provided in a state in which a high pressure gas in the bushing is sealed via a conductor 18 to an electrode foil 17 on the ground side of a condenser cone 16 which is a part of the transformer.
Connected to. Furthermore, this external lead-out terminal 19
Since the remaining part of the transformer formed by the voltage dividing capacitor 11, the leakage transformer 12, the surge voltage divider 13, etc. is connected, it is possible to provide a gas-insulated bushing free from oil leakage.

In the conventional capacitor type bushing, a capacitor cone is formed in close contact with the current-carrying center conductor, and therefore there is a disadvantage in terms of temperature rise. However, in the present invention, as shown in FIG. The capacitor cone 16 is not in contact with the central conductor 23, and therefore, the temperature of the conductor 23 due to energization is not directly transmitted to the capacitor cone 16,
The temperature of the conductor can be kept low, and at the same time, the heat radiation from the conductor is not hindered, so that the temperature rise of the conductor is also reduced. Further, by making the outer shape into a conical shape, it can be housed in the bushing tube and no extra space is required. Furthermore, since the inside of the condenser cone 16 is hollow, if a hole for communicating gas with the upper portion is provided in the adjacent electrode 22 and the central conductor portion in the vicinity, gas circulation is promoted, and it is possible to reduce temperature rise. . The arrows indicated by broken lines in FIG. 1 are for explaining the flow of gas, that is, the gas heated by energization rises inside the condenser cone 16,
If it stays in the upper part, there is a danger that it will become a very high temperature, but the heated gas rises in the center conductor through the vent hole 27a and flows out of the conductor from the upper vent hole 27b. The gas cooled in the upper portion of the bushing passes through the outer circumference of the condenser cone 16, passes through the ventilation hole 27c provided in the bushing 21, and flows down to the lower portion of the condenser cone. In this way, the internal gas circulates naturally and the temperature rise can be suppressed to a low level. Therefore, according to this structure, it can be applied to the bushing for a large current.

Further, the central conductor 23 expands and contracts due to temperature changes depending on the presence or absence of energization, but since the connecting portions 24 and 26 have a flexible structure, excessive stress is not generated.

FIG. 2 shows another embodiment of the present invention. Condenser cone
The connecting portion 22a between the 16 and the conductor 23 has a flexible connecting structure, the upper connecting portion 24a of the center conductor 23 is fixedly connected by bolt fastening or welding, and the lower connecting portion 26a has a flexible connecting structure. On the contrary, the upper connecting portion may have a flexible connecting structure and the lower connecting portion may have a fixed connecting structure.

With such a structure, the center conductor 23 is supported by the upper plate conductor 25, the gravity of the conductor is not applied to the condenser cone 16, and accordingly, the condenser cone 16 does not need a large strength and is inexpensive. It can be anything. Further, even if thermal expansion and contraction of the inner conductor 23 occurs due to energization or the like, the connecting portion 22a and the lower connecting portion 26a absorb the amount of displacement thereof, so that excessive stress does not occur.

In addition, 27d is a ventilation hole provided in the connecting portion 22a, through which the gas inside the condenser cone 16 circulates. Vent holes 27a and 27b can be used together as in FIG.

[Effects of the Invention] As described above, according to the present invention, since the transformer is connected to the electrode foil on the ground side of the capacitor cone, the surge voltage divider for the fault locator for the transmission line and the main circuit AC voltage detection are provided. It is possible to provide a gas-insulated bushing that has a capacitor that can be used as a transformer for an electric appliance, does not require extra space, does not use oil, and is small in size and can also be used for a large current.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a gas insulating bushing of the present invention, FIG. 2 is a sectional view of a gas insulating bushing showing another embodiment of the present invention, and FIG. 3 is a single wire connection of a transmission line inlet. Fig. 4 and Fig. 4 are connection diagrams of the components of the capacitor type transformer, Fig. 5 is an example of the current equipment layout, and Fig. 6 is a configuration diagram of the current gas insulated switchgear. 1 …… Oil-filled capacitor type instrument transformer 2 …… Line side grounding switch, 3 …… Disconnector 4 …… Working grounding switch, 5a, 5b …… Current transformer 6 …… Breaker, 7a, 7b …… Disconnectors for busbar switching 8a, 8b …… Bushing, 9 …… Gas-insulated switchgear 10 …… Main capacitor, 11 …… Voltage dividing capacitor 12 …… Leakage transformer, 13 …… Surge voltage divider 14 …… Transformer box 15a, 15b …… Supporting insulating spacer 16 …… Capacitor cone, 17 …… Electrode foil 18 …… Conductor, 19 …… Lead terminal 20 …… Shield, 21 …… Flange 22 …… Connection electrode, 23… … Center conductor 24 …… Connecting part, 25 …… Bushing upper plate conductor 26 …… Lower connecting part 27a, 27b, 27c, 27d …… Vent hole

Claims (4)

[Claims] 1. A hollow capacitor cone forming a main capacitor of a transformer formed by molding in an insulator tube filled with an insulating gas is arranged coaxially with a bushing center conductor, and a plurality of electrodes forming the capacitor are Of the rods, one end of a conductor for extracting this potential is connected to the grounded electrode foil, and the other end is connected to the transformer through an air insulation terminal provided on the metal short pipe of the insulator pipe support. Gas-insulated bushing characterized by being connected. 2. A hollow capacitor cone insulator is not in contact with the center conductor, and the capacitor cone and the center conductor are connected only by a connecting metal electrode provided at the end of the capacitor cone. 2. The gas-insulated bushing according to claim 1, wherein a vent hole for allowing the gas above the inside of the cone and the gas above the bushing to communicate with each other is provided in the connecting metal electrode or in the central conductor in the vicinity thereof. 3. A gas-insulated bushing according to claim 1, wherein an intermediate portion of the bushing center conductor is supported by a hollow condenser cone, and both ends of the bushing center conductor have a flexible connection structure. . 4. A central conductor is passed through a capacitor cone,
The connection between the conductor of the penetrating portion and the capacitor cone has a flexible structure, one of the upper connecting portion and the lower connecting portion of the central conductor has a fixed connection, and the other has a flexible connecting structure. The gas-insulated bushing according to claim 1.