JPS62142Y2 - - Google Patents

Description

[Detailed explanation of the invention] This invention is used, for example, on the power transmission line side of substations, etc.
The present invention relates to an SF ₆ gas gap device, and particularly to an SF ₆ gas gap device with an improved grounding terminal portion of a ground side electrode that is grounded to the case.

SF ₆ gas gap equipment has excellent features such as no maintenance, no inspection, and excellent insulation properties. For this reason, in recent years, SF ₆ gas-insulated switchyards have been increasingly put into practical use in place of air-insulated switchyards.

However, as is clear from the v-t characteristic diagram shown in FIG. 1, the conventional one-bar jump system has a problem in that it cannot protect switchyard equipment from overvoltage. That is, in FIG. 1, 1 is the v-t characteristic curve of the air rod one-rod jump device, and 2 is the v-t characteristic curve of the SF ₆ gas gap device. In the v-t characteristic curve 1 of this aerial rod one-rod gap device, the voltage gradient is severe, so if it is attempted to protect the switchyard equipment in a region where time is slow, it cannot be protected in a region where time is early. Conversely, if you try to protect switchyard equipment in an area where the time is early, the discharge pressure of the air rod one-rod gap device will become too low in the area where the time is slow, and it will no longer fulfill its role as a protective gap. .

Therefore, there is an earth arrester as a device that compensates for this inconvenience. However, although this earth arrester is superior in terms of overvoltage protection and satisfying the required performance,
The disadvantage is that it is expensive. Therefore, for the above reasons, an SF ₆ gas gap device which is highly economical and has a flat v-t characteristic curve 2 has been developed and is being put into practical use.

However, during the development of the SF ₆ gas gap device, the following point was revealed: When the SF ₆ gas gap device discharges, the ground terminal of the low voltage side electrode of the gap device poses a problem in terms of insulation properties. As a result of various studies on this issue, we found that the discharge time of the SF ₆ gas gap device is extremely short, and an extremely steep current flows through the ground terminal during discharge. It turned out to be.

Next, an example in which the SF ₆ gas gap device as described above is applied to a substation will be described with reference to FIGS. 2 to 4. First, in FIG. 2, 3 indicates the surge impedance of the power transmission line, and 4 indicates the surge impedance of the SF ₆ gas switching station, and a sheath breaker 5 is inserted between these transmission lines and the SF ₆ gas switching station. Reference numeral 6 indicates an SF ₆ gas gap device, which includes a high voltage side electrode 6a, a low voltage side electrode 6b, and a ground terminal portion 6c of the low voltage side electrode 6b. 6d is the metal case of the gap device, 7 is the metal case 6d
8 is the surge impedance of the ground line 7. 9 is a mesh wire.

In the case of a configuration as shown in FIG. 2, when a lightning surge enters from the power transmission line side, the SF ₆ gas gap device 6 starts discharging according to the discharge voltage setting value. If the state before and after this discharge is electrically expressed, it can be replaced with the equivalent circuit shown in FIG. Now, suppose that there is a lightning strike on a power transmission line with a surge impedance of Z ₁ , and a voltage of V _O enters and a discharge voltage V _{O G} as shown in Fig. 4a is generated between electrodes 6a and 6b. The voltage V _OG is divided by the surge impedance Z ₁ of the power transmission line and the surge impedance Z ₂ of the grounding wire 8, and Z ₂ /Z ₁ + is applied to the ground terminal 6c of the low voltage side electrode.
A voltage V _OE of Z ₂ V _OG is generated. This voltage V _1E is repeatedly reflected at the ground point, resulting in a waveform as shown in FIG. 4b. For example, V _OG = 2000Kv, Z ₁ = 350Ω, Z ₂ =
If it is 20Ω, the voltage V _IE of the ground terminal 6c is 108Kv
becomes. This voltage V _IE is extremely high for the insulation of the ground terminal portion 6c of the low-voltage side electrode, and may cause problems such as dielectric breakdown of the ground terminal 6c or induced noise to the nearby low-voltage control cable.

As a means to prevent this, it may be possible to suppress the surge voltage V _IE by inserting a capacitor between the ground terminal part 6c and the metal case 6d, but if the capacitor capacity is made small, there will be no surge suppression effect.
On the other hand, if the capacitor capacity is increased, surges can be suppressed, but this has the disadvantage that the steep current flowing through the capacitor causes induction in the nearby low-voltage control cable.

The present invention was developed in view of the above-mentioned circumstances, and includes a plurality of non-contact elements coaxially attached to an insulating part between a conductive part that fixedly supports a support rod that supports a low-voltage side electrode and a lid of a metal case. A linear resistor is arranged to allow the steep current during discharge to flow through the metal case due to the characteristics of the non-linear resistor, thereby protecting the ground terminal of the low voltage side electrode from surges and reducing induced noise to the low voltage control cable. The purpose of the present invention is to provide an SF ₆ gas gap device that aims to reduce the amount of gas.

An embodiment of the present invention will be described below with reference to the drawings. FIG. 5 is a longitudinal sectional view showing the low voltage side electrode part of the SF ₆ gas gap device, in which 11 and 12 indicate the high voltage side electrode and the low voltage side electrode, and these electrodes 11 and 12 form the gap part. are doing. Both electrodes 11 and 12 are housed in a cylindrical metal case 13 filled with SF ₆ gas, and the support rod 14 of the low-voltage side electrode 12 is inserted into a through-hole in a lid 15 that closes the end of the metal case 13. 15a with a predetermined gap. 16 supports and fixes the support rod 14 of the low voltage side electrode 12, and the support rod 14
This is a ground terminal portion that airtightly closes the lid through hole 15a through which the wire is passed.

Next, FIG. 6 is a diagram showing the ground terminal section 16 of FIG. 5 in detail. That is, this ground terminal portion 16
A plurality of holes 1 having a desired thickness are coaxially formed inside the conductor portion 161 that supports and fixes the support rod 14.
An insulator section 163 provided with 62a, 162b, . . . is arranged. Therefore, the insulator section 163 is held between the lid 15 and the conductor section 161. Holes 162a, 162b of the insulator section 163...
Non-linear resistor 164 mainly made of metal oxide
a, 164b... are stored, and this is used as the spring 165a,
165b... and 166a, 166b... and are electrically connected to the lid body 15 and the conductor portion 161. 167,168 is SF ₆
This is a packing used to seal gas pipes.

Therefore, the SF ₆ gas gap device with the above configuration is
It can be represented by an electrical equivalent circuit as shown in FIG. That is, for the surge impedance Z ₂ of the grounding wire 8 in FIG.
...is connected in parallel. Note that the nonlinear resistors 164a, 164b, . . . simultaneously have capacitance.

As a result, the SF ₆ gas gap device of the present invention has operational differences as compared to the conventional SF ₆ gas gap device as shown in FIG. Figure 8 shows lightning voltage
This shows the voltage before and after the discharge of the SF ₆ gas gap device due to Vo, but the non-linear resistor 16
4a, 164b..., the discharge voltage V _OG appearing between the electrodes 11 and 12 attenuates as shown by the dotted line in the figure a, and similarly the low voltage side voltage V _IE at the ground terminal 16
A voltage as indicated by the dotted line in Figure B is generated.

On the other hand, the nonlinear resistors 164a, 164b
..., the voltages V _OG and V _IE are as shown in Figure 8 a and b.
The voltage waveform will be as shown by the solid line. This means that a part of the discharge current is transferred to the non-linear resistor 164 at the start of discharge.
a, 164b, . . . , and this current I has a waveform with a slow waveform as shown by the solid line in FIG. 8c. It is conceivable to connect only a capacitor to the surge impedance _Z2 of the grounding wire 8, but in this case, a current as shown by the dotted line in FIG. 8c flows.

In particular, the reason why a current waveform with a small current peak value and a slow wave crest susceptibility is obtained as shown in FIG. Due to that. In other words, the non-linear resistors 164a, 164b... exhibit a history characteristic of the VI curve as shown in FIG. 9a,
Therefore, when applying a steep voltage as shown in figure b,
At first, the resistance is relatively high, so no current flows, and then it gradually increases. Even when a step voltage is applied, only a gradually increasing current flows.

In fact, when we tested a 500Kv class SF ₆ gas gap device, we found that the voltage at the ground terminal 16 was less than 1/15 of that of a conventional SF ₆ gas gap device.
Induced voltage to control cable and non-linear resistor 164 when adding 5000PF co-capacitor
The ratio of the induced voltage in the control cable when adding a, 164b, . . . was less than 1/100. As a result,
The insulation of the ground terminal portion 16 is sufficient to meet the structural requirements of No. 10 to No. 120, and the induced noise of the control cable will not be a problem at all. Also, from the experimental results, one non-linear resistor has little effect, and multiple non-linear resistors 164a,
It has been found that when 164b... is dispersed coaxially, it is significantly effective.

As described in detail above, according to the present invention, the grounding terminal portion of the low voltage side electrode is connected to a plurality of nonlinear resistors having a v-i curve history characteristic inside the conductor portion that supports the support rod of the low voltage side electrode. Since the body is distributed coaxially and electrically connected to the lid body that closes the end of the metal case, a non-linear resistor is connected in parallel to the surge impedance of the grounding wire, resulting in a gap. Surge voltage at the start of discharge is suppressed and dielectric breakdown of the ground terminal can be avoided. Furthermore, the non-linear resistor exhibits a relatively high resistance at the start of discharge, blocking the current and gradually increasing the current, so a steep current does not flow into the case, and induced noise to nearby low-voltage control cables is also a problem. It is so small that it does not become a nuisance, and the interference caused by induced noise can be eliminated.

Furthermore, by suppressing the surge voltage, not only can the insulation problem be solved, but also the economically inexpensive feature can be maintained, further increasing the practical value of the SF ₆ gas gap device.

[Brief explanation of the drawing]

Figure 1 shows the conventional aerial rod gap device and the SF ₆
Figure 2 is a configuration diagram of a conventional SF ₆ gas gap device applied to the transmission line side of a substation, Figure 3 is an equivalent circuit diagram of a conventional SF ₆ gas gap device, and Figure 4 is a v-t characteristic diagram of a gas gap device. a, b are waveform diagrams of the voltage generated during lightning surge invasion, Figures 5 to 9.
Figures a and b are for explaining one embodiment of the SF ₆ gas gap device according to the present invention, in which Figure 5 is a longitudinal sectional view showing the low voltage side electrode portion, and Figure 6 is a grounding of the low voltage side electrode. Vertical cross-sectional view showing the terminal part in detail, No. 7
The figure is an equivalent circuit diagram of the SF ₆ gas gap device, Figures 8 a to c are comparative waveform diagrams of voltage and current with and without a non-linear resistor, and Figures 9 a and b are i of the non-linear resistor. FIG. 3 is a diagram showing a -v characteristic and a state of change in current with respect to voltage. 3... Surge impedance of power line, 8...
Surge impedance of grounding wire, 11... High voltage side electrode, 12... Low voltage side electrode, 13... Metal case, 15... Lid body constituting the metal case, 16...
...Ground terminal section, 161...Conductor section, 163...
Insulator portion, 164a, 164b...non-linear resistor.

Claims (1)

[Scope of utility model registration request] A high-voltage side electrode connected to a high-voltage line and a low-voltage side electrode placed opposite to this with a predetermined gap.
In an overvoltage protection SF ₆ gas gap device which is housed in a metal case filled with gas and grounded, _the low voltage side electrode is supported in a through hole in a lid that closes an end of the metal case. A conductor part through which a support rod is inserted and which supports and fixes the support rod is arranged near the through hole of the lid, and a plurality of non-conductors are provided between the conductor part and the lid with respect to the support rod. An insulator part having a storage part capable of coaxially storing and arranging linear resistors is provided in an airtight manner, and a plurality of non-linear resistors are respectively stored coaxially with respect to the support rod in the storage parts of this insulator part. An SF ₆ gas gap device characterized in that the conductor portion and the lid of the metal case are electrically connected.