JPH0386009A - Gas insulation switchgear - Google Patents

Abstract

PURPOSE:To lower a withstand strength and to reduce the size and the cost of a switchgear by arranging the switchgear at the ground side of an impedance machine such as an arrester. CONSTITUTION:In order to prevent overcurrent flow, due to overvoltage, through an impedance machine such as an arrester 41 connected between a main circuit and the ground and/or to interrupt overcurrent by opening a circuit including the impedance machine, a switchgear 42 for temporarily opening the circuit is arranged at the ground side of the impedance machine. By such arrangement, the withstand strength can be lowered when compared with a conventional switchgear being arranged on the main circuit side of the impedance machine, while furthermore the size and the cost of the switchgear can be reduced.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention relates to a gas insulated switchgear (hereinafter referred to as GIS) in which live parts such as a main circuit and a lightning arrester are covered with a metal container filled with gas. It is about improvement.

[Conventional technology]

Figure 4 is a partial cross-sectional view showing part of the configuration of a conventional 500kV GIS, Figure 5 is a single line diagram of the conventional GIS, and Figure 4 shows only the equipment on the right side of the dashed-dotted line A in Figure 5. is illustrated. In these figures, (1) is the ground, (
2) is a bushing for external connection, (3) is a conductor for connection, (4) is a metal cylinder containing conductor (3), and (5) is a disconnection for power operation, although the internal structure is not shown. (6), a power-operated earthing switch (7), and a manually operated earthing switch (
8〉 (see Figure 5), (9) is a current transformer, OO is (a part of) a circuit breaker, and (B) is a zinc oxide type lightning arrester whose detailed configuration will be described later. In both cases, the live parts are covered by a grounded metal container filled with sulfur hexafluoride gas (hereinafter referred to as SF6 gas), which is an excellent insulating gas medium. The lightning arrester (b) is connected between the conductor (3) and the ground via a power-operated disconnector (2) which is an opening/closing means. (to) to [phase] are respectively the disconnection part (5),
Bushing (2), disconnector (6), insulating spacer that separates the gas (SF6 gas) filled in the lightning arrester (b) and supports the live parts, bushing (2) for QQ~α
), disconnector (5), circuit breaker (9) and disconnector (
6). Although not shown in FIG. 4, the current transformer (1) shown to the left of the dashed line A in FIG.
), Busbar disconnector (2), @, Busbar (2).

(Incorporated Foundation), GIS is configured including the earthing switch (To).

Next, the configuration of the lightning arrester (b) will be explained. In Figure 4, lightning arrester 0 is a case (
The case (b) has zinc oxide elements (to), which are sintered bodies mainly composed of zinc oxide, arranged in an equilateral triangle, three in each stage, as a shield (to). The lower end is grounded (Fig. 4) and the upper end is disconnected (disconnector 6). (2) is a partial pressure shielding member that equalizes the electric field distribution, and (2) is a holding member that holds down the stacked zinc oxide element (2) and the shield.

Since the functions of the GIS configured as described above are well known, the explanation thereof will be omitted, and the disconnector O will be explained. A 500 kV class GIS is manufactured by being divided into transportable-sized units, transported to a predetermined installation site, in this example a switchyard, and then assembled as a whole.

After assembly, the bushing (2), conductor (8), disconnector (6), etc. that make up the main circuit are connected to a predetermined test voltage, in this example 1.25E volts (E: normal ground voltage, the same applies hereinafter). A dielectric strength test is carried out by applying the following for 10 minutes.

During this dielectric strength test, the disconnector @ is opened to open the circuit so that overcurrent due to the test voltage of 1.25 E volts does not flow through the earth arrester QC. This is because lightning arresters (b) are required to have an extremely low limiting voltage in order to protect the equipment, so even if the above test voltage is applied, an overcurrent will flow and damage the zinc oxide element (b) due to heat generation. This is to prevent problems such as the risk of overcurrent and the need for a large-capacity test transformer to supply overcurrent. If it is an ordinary switchgear rather than a GIS, it is easy to disconnect the main circuit by temporarily disconnecting the main circuit from the lightning arrester Ql) without using a disconnector 0, but in the case of a GIS, these Since the live parts of the equipment are covered with metal containers filled with gas, it is impossible to do so, so we resort to methods such as operating the disconnector (6) to open the circuit.

In addition, problems such as the risk of damage due to overheating due to overvoltage applied during dielectric strength tests are not limited to the above-mentioned lightning arrester 0, but can also be applied to wound type instrument gas transformers, capacitor type instrument transformers, etc. Commonly found in impedance devices that are connected between the main circuit and ground and operate passively.

[Problem to be solved by the invention]

The conventional GIS is configured as described above, and in order to prevent overvoltage from being applied to lightning arrester 0 and overcurrent flowing during a dielectric strength test of the main circuit conducted at the installation site, disconnector 0 is used to prevent overcurrent from flowing into the main circuit. In other words, it is installed on the electric line side to release the circuit, and the disconnector 0 is 500k
It must be for V circuit, therefore withstand voltage 2
．． Since 36E bolts are required, there are problems in that the size is large, the manufacturing cost increases, and the installation space for the GIS increases.

This invention was made to solve the above-mentioned problems, and provides a small and inexpensive switching means for temporarily opening the circuit of an impedance device such as a lightning arrester during a dielectric strength test of a GIS electrical circuit. The objective is to obtain a GIS with a small installation space.

[Means to solve the problem]

The GIS according to the present invention is provided with a switching means on the ground side of an impedance device such as a lightning arrester connected between a main circuit and the ground.

[For production]

In this invention, when performing a dielectric strength test of GIS, etc., the circuit including the impedance device is opened to prevent overcurrent from flowing through the impedance device such as a lightning arrester connected between the main circuit and the ground due to overvoltage. In order to prevent overcurrent from flowing, a switching means for temporarily opening the circuit is provided on the earth side of the impedance device. Since the withstand voltage strength can be significantly reduced compared to the opening/closing means, the opening/closing means can be made smaller and cheaper.

[Embodiments of the invention]

Figures 1 to 3 show an embodiment of the present invention, in which a disconnection device (6
), Fig. 1 is a partial cross-sectional view showing a part of the configuration of the 500kV GIS, Fig. 2 is a single line diagram of the GIS, and Fig. 3 is a detailed view of the arrester disconnection device (6). It is a sectional view showing operation. In these diagrams, the company is a zinc oxide type lightning arrester, and the conductor (3), the ground, and the
The connection is made via a disconnection device 0 provided on the ground side. The disconnection device part is attached to the flange (31a) of the case.
) and housed in the case 0])
]J1 The terminal board opening on which the zinc oxide element (to) is supported by the insulation support value υ, the contact provided on the terminal board 1112, and the shield (53a missing flange (31a)
), the sliding contactor (goods) installed on the shield (5
4a), A rod-shaped disconnection conductor-1 that reciprocates in the vertical direction while sliding with the sliding contact and comes into contact with and separates from the contact 1 Engages with the flange portion (55a) of the disconnection conductor ■ It consists of a threaded guide Bordeaux that guides it up and down, a fixing nut opening, and an O-ring that seals the sliding part between the disconnecting conductor and the flange (31a).
a) is the state 1 (b) in which the disconnection conductor ■ and the contact
) The figure shows the state in which they are in contact. Incidentally, the insulating support 11 (not shown) is fixed to the flange (31a) of the case, and the one terminal plate is fixed to the insulating support with bolts.

In addition, when the contactor and the disconnecting conductor are separated,
The voltage strength of the insulation or disconnection device (6) between the two is sufficient if it can withstand the voltage of the dielectric strength test of the electrical circuit conducted at the installation site, in this case 1.25 E volts, as shown in Figure 4. Compared to the withstand voltage of 2.36 E volts required for the conventional disconnecting and disconnecting switch O, a withstand voltage strength that is significantly lower is sufficient.

Next, the operation of the separating device will be described.

When performing a dielectric strength test at the location where the GIS is installed, press the disconnection conductor downwards in the figure to open the gap between it and the contactor, as shown in Figure 3 (a), and open the gap between it and the ground. Then apply a test voltage of 1.25 E volts. In this case, the zinc oxide element (2) of lightning arrester 0, the shield (to),
A test voltage of 1.25 E volts is applied to the terminal plate, contacts, etc., but since the lightning arrester (b) and the ground are open, no current flows. Also, as shown in FIG. 3(b), the disconnecting conductor (1) and the contactor (-) are normally connected and the terminal board is fixed by a nut group so that it is in a grounded state.

In the above embodiment, a lightning arrester is used as an example of the impedance device, but other devices connected between the electric line and the ground, such as a winding type voltage transformer, a capacitor type voltage transformer, etc. Similar effects can be achieved even with impedance devices.

In addition, the disconnection R- which is the opening/closing means provided on the ground side
As an example of temporarily opening the disconnection device (6), we have described the case of conducting a dielectric strength test of the electric circuit, but other cases may be used without detracting from the spirit of the present invention. The strength may be appropriately designed according to the required value.

〔Effect of the invention〕

As described above, according to the present invention, since the switching means is provided on the ground side of impedance devices such as lightning arresters, the withstand voltage strength can be significantly reduced compared to conventional devices provided on the electrical line side. An inexpensive opening/closing means can be used, and a GIS with a small installation space can be obtained.

[Brief explanation of drawings]

Figures 1 to 3 show one embodiment of the present invention, with Figure 1 being a partial sectional view showing part of the configuration of a 500kV GIS, Figure 2 being a single line diagram of the GIS, and Figure 3 Figure 4 is a cross-sectional view showing the details and operation of the lightning arrester disconnection device, Figures 4 and 5 are conventional GIS, and Figure 4 is a partial cross-sectional view showing part of the GIS configuration. It is a single line diagram. In the figure, (2) is a bushing, (3) is a conductor, 0υ
(6) is the escape device, and (6) is the disconnection device. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Claims] In a gas-insulated switchgear, which includes a main circuit and an impedance device such as a lightning arrester connected to the main circuit and the ground, and whose live parts are covered with a metal container filled with gas and grounded, the impedance device is a switching means. A gas-insulated switchgear characterized in that it is connected to the earth via a