JPH0126151B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a discharge gap device for protecting a series capacitor.

In series capacitor installations, a protective gap device is used to protect the series capacitor from overvoltage. The currently used gap device will be explained below with reference to FIGS. 1 and 2. C ₁ and C ₂ are series capacitors,
The midpoint P ₁ is connected to the current limiting resistor R ₂ through the coupling resistor R ₁
and the connection point _P2 with the auxiliary gap PG. BPS is a bypass switch, and L is a power transmission/distribution line.

The main gaps G and G' connected in parallel to the series capacitors C ₁ and C ₂ are connected to a first gap G 1 consisting of first electrodes Ga ₁ and Gb _{1 and an} arc connected thereto, as shown in FIG. A second gap G2 consisting of second electrodes _Ga2 and _Gb2 supported by runners 1a and 1b and having a length greater than that _of the first gap _G1 is disposed above the second gap _G2 . The third electrode Gb 3 forms a third gap G ₃ together with _the second electrode Ga ₂ and is housed in a cubicle 3 having an ionized gas discharge hole 2 .

The one first electrode Ga ₁ is insulated from the cubicle 3 via a bushing 4, and the other first electrode Gb ₁ is connected to the cubicle 3 via a bushing 5 (or directly to the cubicle 3 (not shown). z)) installed.

Further, the third electrode Gb ₃ is supported by the cubicle 3 with an insulator 6, and is connected to the cubicle 3 via a conductor 7 extending laterally, and in the illustrated example, the third electrode Gb 3 is connected to the cubicle 3 via the conductor 7 - cubicle 3 - conductor 8. and is connected to the other first electrode _Gb1 to form a circuit. Although Fig. 2 shows the main gap G on the series capacitor C ₁ side, the main gap G' on the series capacitor C ₂ side has almost the same structure, and there are auxiliary gaps in the cubicle 3 depending on the main gap. P.G.
It houses the coupling resistor R ₁ and the current limiting resistor R ₂ and is disposed under the main gap G housing cubicle 3.
Note that 10 is an insulating frame, and 11 is an insulator.

According to the above configuration, an overvoltage is applied between the terminals of series capacitors C ₁ and C ₂ due to a short-circuit current at the time of a power transmission/distribution line fault, and the voltage between the terminals of series capacitor C ₂ reaches the discharge starting voltage of auxiliary gap PG. When the voltage reaches the main gap G, the overvoltage is discharged and the overvoltage is applied to the main gap G side via the coupling resistor _R1 . In this main gap G, since the length of the first gap _G1 is short _, the current is first fired here, and the current flows from
It flows with Y. Therefore, the arc _a1 generated in the first gap _G1 is blown upward by the electromagnetic force of the first loop circuit I, rises between the arc runners 1a and 1b, and reaches the second gap _G2 . When this rising arc a ₂ further rises and reaches the third electrode Gb ₃ ,
The current is X - Cubicle 3 - Conductor 7 - Third electrode
Gb ₃ - Second electrode Ga ₂ - Arc runner 1a - First
Flows from electrode Ga ₁ to bushing 4 and Y.

As the main gap G discharges, the full voltage is applied to the current limiting resistor _R2 , so the other main gap G' is also discharged in the same manner as above, and the series capacitor _C1 ,
Turn off C ₂ . Subsequently, the bypass switch BPS closes,
When the discharges in both main gaps G and G' are extinguished, the ionized gas in the cubicle 3 is quickly exhausted through the exhaust hole 2, and insulation recovery is accelerated. Even if the accident is recovered and the series capacitors C ₁ and C ₂ are reinserted into the line, the gaps G and G' will not be discharged again due to the voltage between the terminals of the series capacitors C ₁ and C ₂ during normal operation.

By the way, according to the inventor's experiments, when the discharge current becomes large, even if the arc _a3 is extinguished, the first electrode
Between Gb ₁ and Ga ₁ , or between arc runners 1b and 1
Re-discharge was observed near the first electrodes Gb ₁ and Ga ₁ of a.

It is an object of the present invention to solve the above-mentioned difficulties and to increase the capacity of the gap device.

As a result of considering the above-mentioned causes, the inventor found that arc a ₃
A major factor is that the ionized gas IG is blown to the right in Figure 2 by the loop force, and a portion of the ionized gas IG is pushed by the air on the side wall of the box 3 and returned to the first gap _G1 as shown by the arrow. discovered. Based on this, the following invention was made and by implementing it, it was possible to prevent re-discharge in the vicinity of the first electrodes Ga ₁ and Gb ₁ .

An embodiment of the present invention will be described below with reference to FIGS. 3 and 4. As can be easily understood from the figure, most of the side of the first electrode Ga ₁ and the arc runner 1a opposite to the opposing electrode, that is, the side facing the box 3, is covered with an insulating barrier 12. The insulating barrier 12 has a semicircular arc cross section, and its radius of curvature is selected to be larger than that of the arc runner 1a and the first electrode _Ga1 .
A gap is interposed between the insulating barrier 12, the first electrode Ga ₁ and the arc runner 1a.
The insulating barrier 12 is fixed to the arc runner 1a with screws 14 via spacers 13, for example.

As described above, according to the present invention, by providing an insulating barrier, gas ionized by the arc can be prevented from returning between the first electrodes even during a large current discharge, and the dielectric strength between the first electrodes can be improved. Since re-discharge can be eliminated, the capacity of this type of gap device can be increased.

[Brief explanation of drawings]

Fig. 1 is an electrical connection diagram showing an example of series capacitor equipment, Fig. 2 is a side view schematically showing a discharge gap device, Fig. 3 is a perspective view of essential parts showing an embodiment of the present invention, and Fig. 4 is FIG. 4 is a sectional view taken along the line A-A' in FIG. 3; Gb ₁ , Ga ₁ ... first electrode, 1b, 1a ... arc runner, Gb ₂ , Ga ₂ ... second electrode, Gb ₃ ...
Third electrode, 3... Cubicle, 12... Insulating barrier, 13... Spacer, 14... Screw.

Claims (1)

[Claims] 1. A first gap G 1 consisting of first electrodes Ga ₁ and Gb ₁ each connected in parallel to a series capacitor inserted in a power transmission/distribution line, and said first electrodes Ga ₁ and _{Gb 1}
a second gap G 2 comprising second electrodes Ga ₂ and Gb ₂ supported by arc runners 1a and 1b, respectively, with _a gap length greater than the first gap G _{1 ;} Said second electrode Ga ₂
a third gap G _{3 consisting of a third electrode Gb 3 disposed} between the widths of and Gb 2 and the one second electrode Ga _{2 ;}
and are housed in a box body 3 having an ionized gas discharge hole 2, and an insulating barrier 12 having a semicircular arc cross section with a radius of curvature larger than that of the arc runner _1a and the first electrode Ga1 is used to connect the arc runner 1a and the first electrode Ga1. The opposite side of the electrode Ga ₁ to the opposite electrode is covered with a gap therebetween, and the third
A discharge gap device for protecting a series capacitor, which prevents hot gas from going around to the first gap _G1 due to the expansion caused by the loop force of the arc _a3 of the gap _G3 .