JPS62170118A - Gas insulated disconnector - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention 3] The present invention relates to a gas insulated disconnect switch, and particularly to a gas insulated disconnect switch that suppresses restriking surges when charging current is cut off.

[Technical background of the invention and its problems] Normally, a disconnector is given the responsibility of opening and closing a loop current with a recovery voltage of 0 to several hundred volts and a current value of 0 to several thousand.
Further, at the rated voltage, the charging current must be switched between several 11 A and several times.

By the way, the electrode part of the conventional SF6 gas insulated disconnector is
It is configured as shown in the figure. A fixed electrode 2 and a movable electrode 3 are housed in a metal tank 1 filled with SFs gas G. Both the fixed electrode 2 and the movable electrode 3 are cylindrical. The tip portion 3a of the movable electrode 3 forms a contact portion in cooperation with the fixed electrode side energizing contact 5 fixed to the inner peripheral surface of the shield 4 provided at the tip of the fixed electrode 2. Further, a movable electrode-side energizing contact 7 attached to a shield 6 is slidably attached to the movable electrode 3. Roughly, at the center of the end face of the fixed electrode 2, a rod-shaped fixed electrode side arc electrode 8 with an enlarged ball-shaped tip is provided, and an end plate 9 provided by retracting in the axial direction from the tip of the movable electrode 3 is provided. A cylindrical movable electrode-side arc electrode 10 concentric with the movable electrode 3 is provided. The fixed electrode side arc electrode 8 is made of an elastic material, and has a slit 11 extending from its tip in the axial direction.
is provided so that contact charge is generated on the contact surface with the arc electrode 10 on the movable electrode side.

In the electrode section shown in FIG. 3, electrode opening is performed as follows. That is, when the movable electrode 3 is driven, the fixed electrode side current-carrying contact 5 and the movable electrode tip 3a are first separated. Then, the fixed electrode side arc electrode 8 and the movable electrode side arc electrode 10 are separated. During this opening, an arc is generated between both arc electrodes, and when the opening distance becomes large, this arc disappears and the interruption is completed.

Generally, in the case of loop current, the breaking current is large, so
The arc occurs repeatedly until the interruption is completed, and the charge is N1! In the case of current, the breaking current is small, so arcing occurs intermittently until the breaking is completed.

The fixed electrode side arc electrode 8 is made of an elastic material as described above, and is provided with the slit 11, so that it is in contact with the movable electrode side arc electrode 10 with contact pressure. Therefore, even after the fixed electrode side energizing contact 5 and the movable electrode tip 3a are separated, the tip of the fixed electrode side arc electrode 8 and the movable electrode side arc electrode 10 are separated and until they face each other. No arc occurs. This serves to prevent arc damage to both arc electrodes 8.10.

However, since the fixed electrode side arc electrode 8 is provided with the slit 11 as described above, an acute angle portion 12 is formed at the opening end of the slit, and this acute angle portion 12 poses a problem in terms of the characteristics of the disconnector.

This will be explained below. Generally, a disconnector is opened and closed with an adjacent circuit breaker open, and the disconnector switches a minute charging current on a short line leading to the circuit breaker.

Figure 4 shows an example of the configuration of a substation. In this diagram,
Busl, BUS2 are bus bars, A, B, C.

D, E, F, G, H, I, J, L, M, N.

O is a disconnector, a, b, c, d, e, f are circuit breakers, TR1
, TR2 is a transformer, and PLI, PL2, and PL3 are power transmission lines.

In the substation having the above configuration, disconnectors A to 0. Circuit breaker a~
r, a substation in which all busbars BUS1 and BUS2 are housed in an SF6 gas-filled container is called a fully gas-insulated substation, and a substation in which only busbars BUS1 and BUS2 are overhead lines is called a composite gas-insulated substation. There is.

In any type of substation, for example, disconnector A opens and closes a short line m to circuit breaker a, and disconnector E
When the circuit breaker is open, the line section n is opened or closed. Further, the disconnector I opens and closes the bus bar BUS1 with the disconnector C1E, N, and the circuit breaker f open.

Now, the above-mentioned disconnector interrupts the charging current of the short line leading to the adjacent circuit breaker, but when it is interrupted, many restrikes occur, and the load side ground voltage waveform is shown in Figure 5. It is known to fluctuate as shown. That is, the minute charging current is cut off almost simultaneously with the contact opening point ○C, and at that time, the instantaneous value ■1 of the power supply voltage at the time of cutoff remains in the line on the load side. 'IJX! Since the voltage changes with alternating current, a voltage equal to the difference between the residual voltage of the line and the power supply voltage is applied between the poles of the disconnector. At this time, the new circuit is still in the middle of the same polarity, and the inter-electrode insulation has not recovered sufficiently, so it is re-ignited at the inter-electrode voltage e1.

Since the capacitance of the load side line is on the order of several hundred to several thousand picofarads, as soon as the transient current caused by the above-mentioned restriking attenuates, interruption is established, and the load side line receives the instantaneous value of the power supply voltage v2. A voltage equal to remains. Since the power supply voltage changes further, restriking occurs again at the electrode-to-electrode voltage e2. Similarly, the electrode voltages e3, e4, e5, e6,
Re-ignition occurs repeatedly at e7, e8, etc.

Naturally, a surge voltage is generated during each of the above-mentioned restrikes.

For example, assume that restriking occurs at point a in FIG. FIG. 6 conceptually shows this expanded in time. What is shown in this figure is a case where the load-side line to be opened and closed is short, and the frequency of the surge voltage is high, and its fundamental frequency reaches several hundred K1-12 to several MH2.

At the time of restriking, a high frequency current flows between the poles of the disconnector. If the disconnector shuts off when the current value shown at point . However, the above is a theoretical matter, and such a phenomenon does not occur in an actual system. In an actual system, the interruption is established when the transient current at the time of restriking has sufficiently attenuated, and the interruption occurs when the voltage of the load side line matches the power supply voltage. Therefore, the residual voltage on the load side line will never exceed the power supply voltage.

The higher the voltage on the load side line at the time of restriking, and the higher the power supply voltage at this time, the greater the surge voltage will occur. Since this surge voltage may deteriorate the insulation of the equipment, it is desirable that it be as small as possible.

On the other hand, the occurrence of restriking is governed by the electric field strength between the disconnector poles. In the conventional disconnector shown in FIG. 3, when the circuit is re-ignited in the middle of opening, the situation is as shown in FIG. 7. As described above, there is an acute angle portion 12 formed by the opening of the slit 11 at the tip of the fixed electrode side arc electrode 8 . The electric field strength increases at this acute angle portion 12, and a restriking arc 13 is generated from this portion toward the arc electrode on the movable electrode side.

When re-igniting between the poles of a disconnector, as can be seen from Figure 5, there are two cases in which the fixed electrode is re-ignited with a voltage between the poles of positive polarity with respect to the movable electrode, and conversely when the voltage between the poles is negative with respect to the movable electrode. There are times when it will be re-ignited. Therefore, there is a polarity effect in the voltage between poles at the time of restriking, and if the voltage between poles at which restriking occurs is different between restriking with positive polarity and restriking with negative polarity, The residual voltage in the load-side line upon completion of interruption is smaller than in the case where this is not the case, and the surge current is also smaller. FIG. 8 shows this state.

Figure 9 shows the discharge initiation voltage due to positive and negative slow wave front voltages of a polar equal electric field gap such as a needle electrode versus a flat electrode and a quasi-equal electric field gap such as a spherical electrode versus a flat plate electrode in SF6 gas. ing.

From this figure, in the polar equality electric field gap, the discharge starting voltage is lower for the positive polarity voltage than the negative polarity voltage, and conversely, for the quasi-equal electric field gap, the negative polarity voltage is lower than the positive polarity voltage. It can be seen that the discharge starting voltage is low. Furthermore, when the gap state is gradually changed from a state where the poles are equal to a state where the poles are almost equal, the discharge starting voltage of the positive polarity and the discharge starting voltage of the negative polarity become almost equal, as shown at point A in Figure 9. There is a state in which

As is clear from the above, the acute angle portion 12 at the slit opening end of the tip of the fixed electrode side arc electrode 8
If there exists an unequal electric field between the poles during opening, a restriking arc occurs at the acute angle portion 12 as shown in FIG.

Therefore, when the charging current is switched on and off many times, the sharp-angled portion 12 is exposed to the arc and gradually becomes rounded. Then, the electric field between the poles gradually approaches the quasi-equal electric field from the pole-equal electric field, and as shown at point A in FIG. 9, the discharge starting voltage of the positive polarity and that of the negative polarity become almost equal. Then, as described above, the residual voltage upon completion of charging current interruption becomes large, and the surge voltage also becomes large.

[Object of the Invention] The present invention has been made based on the above-mentioned circumstances, and provides a gas-insulated disconnector for a gas-insulated substation that reduces the restriking surge voltage that occurs when switching charging current.

[Summary of the Invention] The gas insulated disconnector of the present invention includes a cylindrical movable electrode, a fixed electrode facing the movable electrode, and a fixed electrode that is provided on the fixed electrode and contacts the outer periphery of the tip of the movable electrode to supply electricity. a current-carrying contactor on the electric bridge side, a hollow cylindrical arc electrode on the movable electrode side provided at the center of the tip surface of the movable electrode, and an arc electrode on the movable electrode side provided on the end surface of the fixed electrode facing the vJ electrode. A fixed electrode-side arc electrode for performing arc discharge is provided between the arc electrode and the arc electrode, and both of the arc electrodes are characterized in that the entire surface of the opposing tip portions thereof is formed into a smooth surface.

[Embodiment of the Invention] FIG. 1, in which the same parts as in FIG. 3 are denoted by the same reference numerals, shows an embodiment of the present invention. In this embodiment, the tip of the arc electrode 8 on the fixed electric bridge side is formed into a spherical surface 8a, and the fixed electrode side arc electrode tfi8 is configured to be inserted into and removed from the movable electric bridge side arc electrode 10 in a non-contact state. That is. Further, the inner peripheral edge of the tip opening of the arc electrode on the movable electrode side is chamfered.

In the disconnector of this embodiment having the above configuration, the arc electrode 8 on the fixed electrode side does not have an acute angle part due to the opening end of the slit.
Moreover, since the entire surface of the tip is formed into a spherical surface, a quasi-uniform electric field is created between it and the arc electrode 10 on the movable electrode side. Therefore, as shown in FIG. 9, the discharge starting voltage between the electrodes is lower for the positive polarity and for the negative polarity, so
It is possible to suppress the surge voltage at the time of restriking to a low level. Moreover, since the entire tip of the arc electrode 8 on the fixed electrode side is a spherical surface, the tip will not deform much even if it is exposed to the arc by switching on and off the charging current many times, and even if it is slightly rounded by the arc. Even so, since the electric field between the electrodes is quasi-equal from the beginning, the difference in discharge starting voltage between the positive polarity and the negative polarity between the electrodes can be kept almost constant. Therefore, even if the charging N current is switched on and off many times, the restriking surge voltage will not increase significantly.

In addition, it is possible! 71 When the electrode 3 is driven and the current-carrying contact 5 of the fixed electrode and the movable electrode tip 3a begin to separate, a part of the arc electrode 8 on the fixed electrode side is still connected to the arc electrode 1 on the movable electrode side.
0, but since they are not in contact with each other, an arc is generated between both arc electrodes. However, in the case of a disconnector which is not responsible for opening and closing the loop current, the charging current to be opened and closed is very small, so the damage to both arc electrodes 8.10 caused by the arc is slight and can be ignored.

FIG. 2, in which the same parts as in FIG. 1 are given the same reference numerals, shows another embodiment of the present invention. In this embodiment, the fixed electrode side arc electrode 8 is a disconnector in which a slit 11 is provided like the fixed electrode side arc electrode in FIG.
is chamfered at a certain curvature to form a curved surface 14, but the rest is the same as in FIG.

In the embodiment with the above configuration, the fixed N pole side arc electrode 8
Since the opening end of the slit 11 is chamfered to form a curved surface 14, the electric field between the arc electrode 8 on the fixed electrode side and the arc electrode on the movable electrode side can be made into a quasi-uniform electric field. Therefore, in this embodiment, as can be seen from FIG. 9, the discharge starting voltage between the electrodes is lower for the negative polarity than for the positive polarity, so it is possible to suppress the surge voltage at the time of restriking to a low level. .

In addition to the above, effects similar to those of the embodiment shown in FIG. 1 described above can be obtained.

[Effect of the Invention J As explained above, the gas insulated disconnector of the present invention can stably suppress the surge voltage at the time of restriking to a low level even if the charging current is switched on and off many times.

[Brief explanation of drawings]

Fig. 1 is a sectional view of the main parts of one embodiment of the present invention, Fig. 2 is a sectional view of the main parts of another embodiment, Fig. 2 is a sectional view of the main parts of a conventional disconnector, and Fig. 4 is a sectional view of the main parts of a conventional disconnector. A circuit diagram showing an example of the configuration of a substation, Figure 5 is a waveform diagram to explain the surge at the time of restriking, and Figure 6 is a waveform diagram to explain the surge at the time of restriking.
The figure is a waveform diagram to explain the high-frequency oscillating voltage and current at the time of restriking, Figure 7 is a cross-sectional view to explain the restriking arc between poles, and Figure 8 is the positive polarity and negative polarity between poles. A diagram for explaining the restriking situation when there is a difference in discharge starting voltage in polarity. Figure 9 is a diagram for explaining the firing voltage for an equal electric field under the tank and a quasi-equal electric field in SF6 gas. It is a diagram. 1...metal tank, 2...fixed electrode, 3...movable electrode, 4.6...shield, 5...fixed electrode Side energizing contact, 7...
...Movable electrode side energizing contact, 8...Fixed electrode side arc electrode, 9...End plate, 1o...
...Movable electrode side arc'R pole, 11...Slit, 12...Acute angle part, 14...
curved surface. Applicant's agent Patent attorney Takehiko Suzue Figure 7

Claims (1)

[Claims] A cylindrical movable electrode, a fixed electrode facing the fixed electrode, a current-carrying contact on the fixed electrode side that is provided on the fixed electrode and contacts the outer periphery of the distal end of the movable electrode to conduct electricity, and a distal end surface of the movable electrode. A fixed electrode side arc electrode that performs arc discharge between a hollow cylindrical movable electrode side arc electrode provided at the center and the movable electrode side arc electrode provided on an end surface of the fixed electrode opposite to the movable electrode. A gas insulated disconnector, characterized in that both arc electrodes have a smooth surface on the entire surface of their opposing tips.