JPS61227325A - Gas insulated circuit breaker - 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] The present invention relates to gas insulated equipment, and relates to a gas insulated disconnect switch that is capable of suppressing high frequency surges that occur when the gas insulated disconnect switch is operated. .

[Technical background of the invention and its problems]

Gas-insulated switchgears have been widely used in recent years as switchgears for high-voltage circuits used in substations. This gas insulated switchgear is used for busbars, interrupters, disconnectors, etc.
Other accessory equipment is housed in a grounded metal container, which is highly stable, inert, nonflammable, odorless, and harmless, and has a dielectric strength 2 to 3 times that of air. The SF6 having an insulating property such as S is insulated and maintained by S, and is used as a switching device for a high voltage circuit.

Such devices generally have a coaxial structure, and surges generated within the device propagate with almost no attenuation. It is a well-known fact that high frequency surges are generated in gas-insulated switchgear due to the operation of disconnectors and interrupters. Especially when operating a disconnector, the rising part of the wave crest is 2 to 3 ns.
The maximum peak value of the high frequency vibration of several MHz that follows is °'
A surge voltage that is twice or more (2.0 pu or more) the peak value of the constant operating voltage may occur. The steep wave crest of this surge has caused dielectric breakdown in oil bushings, and the peak value of the surge has caused ground faults from arcs between the poles of disconnectors to grounded metal containers. Examples have been reported. In addition, these surges are caused by the grounding system VC of the gas insulated switchgear! ! This can lead to various types of radio interference and damage to low-voltage control circuits.

Therefore, it is necessary to suppress the high frequency surge generated within the gas insulated switchgear by some means.

A method shown in FIG. 5 has been considered as one method for suppressing high frequency surges that occur when operating a disconnector.

That is, the figure is a cross-sectional view of a disconnector of a gas-insulated switchgear. In the figure, 1 is a grounded metal container, 2 is an insulating spacer attached to this grounded metal container 1, and the inside of the grounded metal container J is sealed and insulated. Gas 3 is sealed. Inside the grounded metal container 1, a pair of fixed electrodes 4* and 4b are disposed close to each other with their axes aligned and facing each other.
Supported by SA2VC. Each fixed electrode 4ae4b is hollow, and contacts 5m and 5b are provided on the inner peripheral surface. Inside one of the fixed electrodes 4b, the outer peripheral surface is connected to the contact 5b) I
A movable electrode 6 is provided which is in c-contact and is slidable in the axial direction of the fixed electrode 4b, and an arc contact 8 is provided at the tip of the movable electrode 6. Further, an operating mechanism 10 is provided outside the grounded metal container, and this operating mechanism 1
The operating force of 0 is transmitted to the movable electrode 6 via the operating rod 9, and the movable electrode 6 can be moved forward and backward in the direction of the fixed electrode 4a, thereby allowing it to move toward and away from the fixed electrode 4&. ing. 7 is a resistor provided at the tip of the fixed electrode 4a. Also, 1λ is 4m for each fixed electrode, 4bV
12 is a connecting electrode.

In such a configuration, high frequency surges are suppressed by the resistor 7.

This is the same method as the so-called resistor closing of the disconnector, in which the resistor 2 is connected to the tip of the fixed electrode 4a of the disconnector. If restriking occurs between the disconnector and the movable electrode 6, this current will necessarily pass through the resistor 7. Therefore, the surge is quickly absorbed by this resistance and does not propagate.

At this time, the interelectrode voltage immediately before restriking is applied to the resistor 7, so a considerable insulation distance is required to prevent dielectric breakdown of the resistor 2 due to this voltage. Therefore, the stroke of the movable electrode is more than twice that of the case where the resistor 7 is not connected, and the length of the disconnector itself increases at the same time.
.

The operating mechanism 10 also needs to be strong enough to handle long strokes. In addition, connecting the resistor 7 to the high voltage side complicates its structure, which may cause failure and reduce the reliability of the gas-insulated switchgear.
In particular, high current flows through the high-voltage side conductor, so consideration must be given to heat, and at the same time, countermeasures against vibrations when operating the disconnector are also required. It is not a good idea to install a mechanism with a complicated structure in such a bad environment.

Unlike interrupters, disconnectors are usually installed in large numbers in a substation, so the cost and reliability of this part are very important to the cost and reliability of the entire substation.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a gas-insulated disconnect switch that can effectively suppress disconnector surges, has a highly reliable, compact, and inexpensive structure.

[Summary of the invention]

In order to achieve the above object, the present invention is characterized in that a substantially cylindrical structure made of a magnetic material is installed inside a grounded metal container surrounding the electrode while maintaining insulation.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a front cross-sectional view showing one embodiment of the present invention, and the same parts in the figure as in FIG. 5 are given the same reference numerals, and their explanation will be omitted.

As shown in the figure, this device eliminates the conventional surge absorbing resistor 7 provided on the fixed electrode 4a, shortens the distance between the fixed electrodes 4ge and 4b, and reduces the distance between the fixed electrodes 4ge and 4b. Since the mechanical strength of the electrode structure is relaxed and the electrode structure has no resistance 7,
For simplification, a cylindrical structure 16 is prepared and installed inside the grounded metal container 1 in such a way that the ribs are placed between the insulating spacers 2 to surround the entire area where the electrodes 4m and 4b are provided. At this time, it is preferable that the central axis of the grounded metal container and the central axis of the structure 16 coincide with each other in terms of insulation design.
Further, the grounded metal container 1 has a center part larger than the inner diameter of the seventh rung 1f, and a gap 3a is provided between the grounded metal container J and the structure J6 to provide electrical insulation.

Note that the structure 16 is made of a plurality of thin magnetic materials laminated.

By the way, magnetic materials generally have a large relative magnetic permeability. For example, iron has μ=sooo, and a magnetic flux 5000 times that in a vacuum is generated. Therefore, such a magnetic body f:
If it is installed inside a grounded metal container, the inductance of this part will be quite large. For example, the inductance of iron with an outer diameter of 503, a thickness of 1 clI, and a length of 1 m is μ.: Magnetic permeability in vacuum, μmi 5000.

do: outer diameter of the magnetic material 16, dI: inner diameter of the magnetic material 16, tn(): Natural logarithm.

This large inductance acts to blunt the wavefront of a step wave with a wavefront length of 2 ns to 3 ns that occurs when the disconnector is re-ignited. To explain this, 1
Consider the equivalent circuit shown in figure g2. 15 is the equivalent inductance of the magnetic material structure 16′ given by equation (1), 14
This is the characteristic impedance of gas insulated switchgear, and the current flowing through this isometric resistance represents the surge propagating within the gas insulated switchgear. 13 shows the step wave voltage due to restriking between the disconnector poles.If the step wave is generated at t=0 and the circuit Manpuku equation (2) is solved, the current l flowing through the resistor JIK can be found.

The solution to equation (2) that satisfies the initial conditions of 1=0 and i=0 is given by: Figure 3 shows the changes in the amount. LO value (1
), the characteristic impedance of a typical gas-insulated switchgear is about 700, so the rise time of the wavefront portion of 1 is +÷=0.3 (μ seconds), and the inductance This is 100 times more than without it.

If the cylindrical structure 16 made of magnetic material is electrically insulated from the grounded metal container 1, the surge current will flow inside the magnetic material structure 16 and lose its effect as an inductance. It is important to prevent this from happening.

Next, the surge suppressing effect of the structure 16 will be specifically explained.

For example, let us calculate the voltage increase rate at the wavefront portion of the surge waveform given by equation (3) in a 550 kV system. V
Assign a peak value of 450 kV and set the rise time to 0.
If the voltage change rate is 3 μ seconds, this value is smaller than the voltage change rate of 1800 kV/A seconds of the 550 kV system lightning in/out test waveform, which may cause dielectric breakdown of the oil bushing or the grounding system. This is an acceptable value for those who are busy.

The voltage change rate given by equation (3) is maximum when 1=0, but let's find the main frequency components at this point.

Differentiate 1 given by equation (3) with respect to t, t'=oI--
If we enter , we obtain the following equation as the current change rate at t=OVc.

In general, the peak value is 71 frequencies! The voltage ν is τ;
It is expressed as πft ・−(7), and t=
The voltage change rate at 0 is obtained by making the voltage change rate given by equation (6) equal to the voltage change rate given by equation (8). By substituting R=700, I, and -20 μH, the frequency f becomes 550 kHz. Therefore, the current waveform given in Fig. 3 only includes frequency components of 550 kHz or less, and even if this surge waveform propagates inside the gas-insulated switchgear, high frequencies of 550 kHz or more cannot be generated. All of the disconnector surges at various all-GLS type substations that have been experienced to date have been caused by I.
MH! That was it. Therefore, it can be seen that if the new circuit device according to the present invention is adopted in such a type of substation, high frequencies that cause insulation problems will not be generated, and a great effect will be obtained.

When the cylindrical structure 16 made of magnetic material is installed at a location away from the poles of the disconnector, the steep waves generated between the poles of the disconnector are considered to be the open end of the part where the cylindrical structure 16 is installed. , it will be reflected.

Therefore, although it is effective in preventing steep waves from propagating, it is not effective in removing steep waves.

In comparison, if the cylindrical structure 16 is installed near the poles of the disconnect switch, which is the source of steep waves, the steep waves will be transmitted to other locations in the gas-insulated switchgear unless they pass through this part. Therefore, steep waves can be effectively removed.

It goes without saying that the present invention can be carried out by appropriately modifying the embodiment k described above and shown in the drawings without changing the gist of the invention. For example, in the previous embodiment, the structure 16 Although it was assumed that a conductive magnetic material such as iron is used as the material, if a high resistance magnetic material such as ferrite is used, there is no need to maintain insulation from the grounded metal container J, which is advantageous in terms of design. Also, other magnetic materials with large μ, such as f-malloy μ = 100,000 pure iron fi = 2
00,000 sp4-my ap = 1,000,
If 000 or the like is used, a similar effect can be obtained with an even smaller cylindrical structure.

In addition, in FIG. 1, the cylindrical structure 16 made of magnetic material is installed to cover the poles of the disconnector, but as shown in FIG. A similar effect can be obtained by installing cylindrical structures 16m and 16b in the cylindrical structure, and since the space between the poles can be widened, the insulation design between the poles of the disconnector, which has a complicated structure, can be easily designed. You can reduce the diameter of the vessel.

In addition, although the first embodiment has been described here for a single-phase disconnector, the same effect can be obtained when applied to a three-phase bulk disconnector. Particularly when applied to a three-phase collective disconnector, the total sum of alternating current flowing inside the magnetic material becomes zero, which is advantageous since there is no need to consider heat generation of the magnetic material.

〔Effect of the invention〕

As stated above, in the present invention, a cylindrical structure made of a magnetic material is installed in a grounded metal container surrounding an electrode.
Since the structure may be installed in a grounded metal container, it is not affected by heat generated by the high voltage conductor, and the structure can be simplified and manufactured at low cost. In addition, since it can be installed at ground potential, the high voltage conductor side does not have a complicated structure and does not particularly reduce reliability. Therefore, the present invention can be used without reducing the reliability of gas insulated switchgear. Furthermore, the present invention provides an inexpensive and highly reliable gas insulated disconnector that can attenuate the disconnector surge by an inexpensive method without significantly changing the size and size of the gas insulated disconnector from conventional ones. be able to.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a disconnector according to an embodiment of the present invention, and FIG.
The figure is an equivalent circuit showing the action of the present invention, Figure 3 is a step wave response waveform showing the effect of the present invention, Figure 4 is a sectional view of a disconnector showing another embodiment of the present invention, and Figure 5 is a sectional view showing a conventional example. DESCRIPTION OF SYMBOLS 1... Grounded metal container, 2... Spacer, 3... Insulating gas, 4... Fixed electrode, 5... Contact, 6...
Movable electrode, 7... Resistor, 8... Arc contact,
9... Operating rod, 10-... Operating mechanism, 11... High voltage center conductor, 12... Connection electrode, 13... Step wave generation source, 14... Characteristic impedance of gas insulated switchgear (70Ω), 15--magnetic material structure 160 equivalent inductance, 16--magnetic material structure. Applicant's agent Patent attorney Takehiko Suzue Figure 2 Figure 3

Claims (3)

[Claims] (1) In a gas-insulated disconnect switch in which a pair of switching electrodes on a fixed side and a movable side are insulated and held together with an insulating gas in a grounded metal container, the switching electrodes are surrounded in a grounded metal container and are made of magnetic material. A gas insulated disconnector characterized in that a cylindrical structure is provided and the structure is insulated. (2) The gas insulated disconnector according to claim 1, wherein the structure has a size that surrounds the switching electrode over almost the entire area. (3) The gas insulated disconnect switch according to claim 1, characterized in that at least one structure is installed separately for each of the movable and fixed electrodes with respect to the gap between the poles of the disconnect switch.