JPH08248065A - Voltage detector for switchgear - Google Patents

Abstract

PURPOSE: To obtain a voltage detector for switchgear in which the secondary circuit is reduced in size while stabilizing the output voltage by providing a guard electrode, while holding microgaps, on the outer circumferential part of an electrode and then grounding the guard electrode. CONSTITUTION: A disc electrode 12 is disposed oppositely to a main circuit conductor 11 and the electrode 12 is fixed with an insulated wire 14 connected with the secondary circuit. A doughnut-like guard electrode 17 is provided around the electrode 12 through a microgap and secured to a board wall 15 by means of upper and lower securing rods 18a, 18b and thereby it is set at the ground potential. The securing rod 18a is slightly thinner than the securing rod 18b and since it is slidable freely, the rate of electric line of force being interrupted is varied according to the position of the guard electrode 17. Consequently, output voltage can be controlled by regulating the height of the guard electrode 17 while fixing the capacitance of secondary circuit. Height of the guard electrode 17 can be regulated with low voltage because it depends on the static field.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-contact type voltage detecting device used for detecting an operating voltage of a switchgear, and more particularly to a secondary circuit having a fixed electrostatic capacitance. The present invention relates to a switchgear voltage detection device capable of downsizing and stabilizing an output voltage.

[0002]

2. Description of the Related Art FIG. 4 is a side view showing a structural example of a gas insulated switchgear which is an example of a switchgear. In FIG. 4, the inside of the box 1 whose outer periphery is airtightly surrounded by a mild steel plate is a partition wall 2 which is vertically provided near the front surface on the left side in the figure, and includes a front breaker chamber 1a and a rear busbar chamber 1b. The circuit breaker chamber 1a and the busbar chamber 1b are filled with a sulfur hexafluoride gas (hereinafter abbreviated as an insulating gas) at a gas pressure substantially equal to the atmospheric pressure.

Of these, a circuit breaker 3 equipped with a vacuum interrupter 3a is housed in the circuit breaker chamber 1a, and the circuit breaker 3 is connected to an insulating bushing 9 mounted in a through hole (not shown) of the partition wall 2. Has been done. The insulating bushing 9 has the same configuration on the upper and lower sides.

Further, a breaker 4 is provided at the ceiling of the bus room 1b.
A is attached, one terminal of which is connected to the upper insulating bushing 9 through the connecting conductor 8, and the other terminal is connected through the connecting conductor 8 to the bus bar 5 fixed to the rear insulator 6. . The bus bar 5 interconnects the adjacent boards.

On the other hand, a disconnector 4A is provided at the bottom of the bus room 1b.
A disconnecting switch 4B having the same shape as the above is attached, one terminal of which is connected to a lower insulating bushing 9 via a connecting conductor 8 and the other terminal is attached vertically behind the bottom plate via the connecting conductor 8. It is connected to the upper terminal of the cable head 7.

The cable 7a connected to the cable head 7 receives electric power. Also,
The voltage received by the cable 7a is detected via the capacitance between the connection conductor 8 and the electrode 10 which is insulated from the box body 1 and has the height h.

That is, it is a generalized voltage detecting device in which the voltage is detected by dividing the voltage on the high voltage side and the secondary circuit (not shown) by C-C. Figure 5
FIG. 4 is a diagram showing an equivalent circuit of this voltage detection device.

In FIG. 5, the electrostatic capacitance between the connecting conductor 8 and the electrode 10 is C ₁ , the electrostatic capacitance of the secondary circuit is C ₂ , and C _{1 with} respect to the operating voltage V ₀ of the switch gear. And C ₂
V ₁ is obtained by the partial voltage of 1 to detect the presence or absence of the voltage of the main circuit conductor 11.

Generally, the capacitance C ₁ between the connecting conductor 8 and the electrode 10 is several p because the insulation distance is several hundred mm.
F, and the capacitance C ₂ of the secondary circuit is several tens nF.
Is used.

Therefore, a voltage V _{1 of} several V is obtained for an operating voltage V _{0 of} several 10 kV. And this voltage V
₁ is input to a voltage detection device (not shown). By the way, in the voltage detection device having such a configuration, the electrostatic capacitance C ₁ between the connection conductor 8 and the electrode 10 greatly changes depending on the arrangement state in which the connection conductor 8 crosses the electrode 10 and the installation state of the electrode 10. .

In particular, in the installed state of the electrode 10, as shown in FIG. 6, the height h between the electrode 10 and the box body 1 is h = 0 mm.
To 300 mm, the electrostatic capacitance C ₁ between the connecting conductor 8 and the electrode 10 changes, and the output voltage V ₁
Changes about 3 times. Therefore, in order to adjust the output voltage V ₁ to several V, the electrostatic capacitance C ₂ of the secondary circuit must be adjusted.

However, in this case, when the electrostatic capacitance C ₂ of the secondary circuit is changed, the capacitors are connected in series and in parallel for adjustment, so that the entire secondary circuit becomes a plurality of capacitors and the secondary circuit is formed. Becomes larger, and fine adjustment becomes difficult.

Further, since this capacitor is connected to the electrostatic capacitance C ₁ between the connecting conductor 8 and the electrode 10 of the main circuit, a capacitor having a high withstand voltage is taken into consideration in consideration of surge voltage intrusion. Is used. Therefore, there is a problem that the capacitor itself is large-sized and it becomes difficult to connect a plurality of capacitors.

[0014]

As described above, in the conventional switchgear voltage detection device, not only is the secondary circuit increased in size, but it is difficult to finely adjust the output voltage. There was a problem.

An object of the present invention is to reduce the size of the secondary circuit and stabilize the output voltage by adjusting the electrostatic capacity on the high voltage side and fixing the electrostatic capacity of the secondary circuit. Another object of the present invention is to provide a switchgear voltage detection device capable of performing the above.

[0016]

In order to achieve the above object, first, in the invention corresponding to claim 1, an electrode is provided facing a main circuit conductor to form a capacitance, and a secondary circuit is formed. In the switchgear voltage detecting device that divides the voltage with the impedance of the guard electrode, a guard electrode is provided on the outer peripheral portion of the electrode while holding a minute gap, and the electrode is grounded.

Here, especially as the guard electrode, it is desirable to provide a guard electrode whose step difference from the electrode can be adjusted. Further, in the invention corresponding to claim 3, an electrode is provided so as to face the main circuit conductor, and a guard electrode is provided on the outer peripheral portion of the electrode to form an electrostatic capacitance, which is divided by the impedance of the secondary circuit. In a switchgear voltage detection device, a protrusion is provided on a guard electrode.

Further, in the invention according to claim 4, an electrode is provided so as to face the main circuit conductor, and a guard electrode is provided on an outer peripheral portion of the electrode to form a capacitance, and an impedance of the secondary circuit is provided. In the voltage detecting device for the switchgear that divides the voltage by means of an electrode, an insulating layer made of an insulating material is provided at a portion where the electrode faces the main circuit conductor.

Further, in the invention according to claim 5, an electrode is provided so as to face the main circuit conductor, and a guard electrode is provided on the outer peripheral portion of the electrode to form a capacitance, thereby making impedance of the secondary circuit. In a voltage detecting device for a switchgear that divides voltage with and, an electrode is provided with irregularities of a predetermined shape on the surface facing the main circuit conductor. Here, it is particularly preferable that the irregularities are circumferential irregularities or linear irregularities.

[0020]

Therefore, in the switchgear voltage detecting device of the invention according to claim 1, a guard electrode (a guard electrode capable of adjusting a step with the electrode) is provided on the outer peripheral portion of the electrode while maintaining a minute gap. If the height of the electrode and the guard electrode is changed by grounding the electrode, the line of electric force formed by the main circuit conductor and the electrode is blocked by the guard electrode, and the electrostatic capacitance between the main circuit conductor and the electrode is reduced. Since it changes, the capacitance of the secondary circuit can be fixed, and the output voltage can be adjusted by the height of the guard electrode.

Thus, the capacitance formed between the main circuit conductor and the electrode can be controlled, the impedance of the secondary circuit can be fixed, the voltage division ratio can be determined, and the voltage can be detected.
In the switchgear voltage detecting device according to the third aspect of the present invention, by providing the protrusion on the guard electrode, the electric field strength is increased, and when an excessive surge voltage enters, discharge is induced on the protrusion. Thus, it is possible to prevent the surge voltage from entering the secondary circuit.

As a result, the secondary circuit is protected from the surge voltage, and the structure having a high withstand voltage is unnecessary. Further, in the switchgear voltage detecting device of the invention according to claim 4, by providing an insulating layer made of an insulating material at a portion where the electrode faces the main circuit conductor, the electric field strength increases and an excessive surge occurs. When a voltage intrudes, it is possible to prevent discharge to the electrodes and prevent surge voltage from invading the secondary circuit.

As a result, the secondary circuit is protected from the surge voltage, and the structure having a high withstand voltage is unnecessary. Furthermore, in the voltage detector for a switchgear of the invention according to claim 5, the electrode is provided with irregularities of a predetermined shape (circumferential irregularities or linear irregularities) on the surface facing the main circuit conductor. This increases the apparent electrode area and increases the electrostatic capacitance between the main circuit conductor and the electrode, so that the outer diameter of the electrode for obtaining the same electrostatic capacitance can be small. As a result, the size of the secondary circuit can be reduced.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention controls the capacitance formed between a main circuit conductor and an electrode by providing a guard electrode around the electrode and adjusting the height of these electrodes. The guard electrode is insulated from the electrode and is connected to a box or the like.

In addition, a minute protrusion is provided on the guard electrode,
At the time of excessive surge voltage intrusion, discharge should be induced in the protrusion. Further, an insulating layer made of an insulating material such as epoxy resin is provided on the electrodes of the secondary circuit to prevent discharge to the electrodes when an excessive surge voltage enters.

Furthermore, since the electrostatic capacitance between the main circuit conductor and the electrodes is as small as several pF, the surface of the electrodes should be provided with irregularities of a predetermined shape to increase the apparent electrode area. To

Embodiments of the present invention based on the above concept will be described below in detail with reference to the drawings. (First Embodiment) FIG. 1 is a block diagram showing a switchgear voltage detection device according to a first embodiment of the present invention.

That is, in FIG. 1, the main circuit conductor 11
The disk-shaped electrode 12 is installed so as to be opposed to the electrode 12 with a constant insulation distance, and the electrode 12 is attached with an insulating wire 14 fixed by a bolt 13.
It is connected to a secondary circuit (not shown).

Here, the electrode 12 is fixed by an insulating rod 16 fixed to the board wall 15. In addition, the guard electrode 17
Is provided around the electrode 12 in a donut shape, and is fixed to the board wall 15 by the upper fixing rod 18a and the hollow lower fixing rod 18b, and is at the ground potential.

Here, the upper fixing rod 18a has a slightly smaller diameter than the inner diameter of the lower fixing rod 18b and is slidable so that the guard electrode 17 can be moved. The upper fixing rod 18a and the lower fixing rod 18b are attached to the bolt 1
It is fixed by 9.

Further, the guard electrode 17 is provided with a minute projection 20. In the switchgear voltage detection device of the present embodiment configured as described above, a copy of the electric force line is shown by a dotted line in the figure, but the ratio of the electric force line being interrupted depending on the position of the guard electrode 17 Will change.

That is, if the height of the guard electrode 17 is increased, many lines of electric force are blocked, and conversely, if the height of the guard electrode 17 is reduced, the number of lines of electric force is reduced. As a result, the capacitance between the main circuit conductor 11 and the electrode 12 changes, and if the height of the guard electrode 17 is lowered, the capacitance is increased, and conversely, the height of the guard electrode 17 is increased. If so, the capacitance will decrease. Since this electrostatic capacitance changes intricately depending on the electrode arrangement, it is difficult to obtain a value by calculation.

Therefore, the above-mentioned FIG. 6 shows that the present inventors experimentally determined this relationship as the output voltage V ₁ . Figure 6
In the above, h is the distance of the step between the electrode 12 and the guard electrode 17. The secondary circuit is fixed at several 10 nF. Further, the main circuit conductor 11 having a diameter of 60 mm was used, and the insulation distance was set to 200 mm.

From FIG. 6, the output voltage V ₁ is measured by the guard electrode 1
It can be seen that when 7 is lowered below the electrode 12 and h is increased, there is a tendency for saturation, but a significant increase. This is because the electrostatic capacitance between the main circuit conductor 11 and the electrode 12 becomes large, and the voltage division ratio with the electrostatic capacitance of the secondary circuit becomes large.

Therefore, the output voltage V ₁ can be controlled by fixing the capacitance of the secondary circuit and adjusting the height of the guard electrode 17. Since the height of the guard electrode 17 is determined by the electrostatic field, it can be adjusted at a low voltage and can be easily adjusted at the factory.

As a result, the electrostatic capacity of the secondary circuit, that is, the capacitor can be fixed, and the size can be reduced with a simple structure. When an excessive surge voltage enters the main circuit, the protrusion 20 is provided on the guard electrode 17, so that discharge can be induced to the guard electrode 17. This is because the electric field strength of the protrusion 20 is increased by the electrode 12.

As a result, the surge voltage is applied to the guard electrode 1
It is possible to prevent the damage of the secondary circuit due to the surge voltage by supplying electricity from 7 to the ground. As described above, in the present embodiment, in the voltage detection device in which the disk-shaped electrode 12 is provided so as to face the main circuit conductor 11 in the switch gear to form the electrostatic capacitance and the voltage is divided by the impedance of the secondary circuit. , A guard electrode 17 is provided around the electrode 12 to be grounded,
By changing the height of the electrode 12 and the guard electrode 17,
The lines of electric force formed by the main circuit conductor 11 and the electrode 12 are blocked by the guard electrode 17, and the capacitance between the main circuit conductor 11 and the electrode 12 changes, so that the capacitance of the secondary circuit is fixed. Then, the output voltage can be adjusted by the height of the guard electrode 17 for stabilization.

This makes it possible to control the electrostatic capacitance formed between the main circuit conductor 11 and the electrode 12, fix the impedance of the secondary circuit, determine the voltage division ratio, and perform voltage detection. .

Further, by providing the protrusions 20 on the guard electrode 17, when the electric field strength increases and an excessive surge voltage intrudes, discharge is induced in the protrusions 20 and the surge voltage intrudes into the secondary circuit. Can be prevented.

As a result, the secondary circuit is protected from the surge voltage, and the structure having a high withstand voltage is unnecessary. (Second Embodiment) FIG. 2 is a partially enlarged sectional view showing a voltage detecting device for a switchgear according to a second embodiment of the present invention.

That is, in this embodiment, as shown in FIG. 2, an insulating layer 22 made of an insulating material is provided on the surface of the portion where the disk-shaped electrode 21 faces the main circuit conductor 11. In addition, 23 is an insulating rod for fixing the electrode 21, and 2
Reference numeral 4 is a bolt for connecting an insulating wire connected to a secondary circuit (not shown).

In the switchgear voltage detecting device of the present embodiment having the above-described structure, by forming the insulating layer 22 on the surface of the electrode 21, when the electric field strength rises and an excessive surge voltage intrudes. The discharge of the electrode 21 can be prevented, and the surge voltage can be prevented from entering the secondary circuit.

That is, the surge voltage does not enter the electrode 21 unless the insulating layer 22 is broken through. For this reason, as the insulating material of the insulating layer 22, for example, an excellent insulating material having a dielectric strength of impulse of about 50 kV / mm, such as epoxy resin, is used and has an insulating thickness of several mm.

As a result, the secondary circuit is protected from the surge voltage, and the structure having a high withstand voltage is unnecessary. As described above, in this embodiment, the electrode 21 is provided so as to face the main circuit conductor 11.
And the guard electrode 1 is provided on the outer periphery of the electrode 21.
In the voltage detection device of the switchgear, in which 7 is provided to form an electrostatic capacitance and the voltage is divided by the impedance of the secondary circuit,
By providing an insulating layer 22 made of an insulating material such as an epoxy resin at a portion where the electrode 21 faces the main circuit conductor 11, when the electric field strength increases and an excessive surge voltage enters,
It is possible to prevent discharge to the electrode 21 and prevent surge voltage from entering the secondary circuit.

As a result, the secondary circuit is protected from the surge voltage, and the structure for increasing the withstand voltage becomes unnecessary. (Third Embodiment) FIG. 3 is a partially enlarged sectional view showing a voltage detecting device for a switchgear according to a second embodiment of the present invention. The same parts as those in FIG. There is.

That is, in the present embodiment, as shown in FIG. 3, the disc-shaped electrode 25 is provided on the surface facing the main circuit conductor 11 with gentle wavy irregularities in a circular shape or a wavy shape. Circumferential or linear irregularities are provided.

Reference numeral 23 is an insulating rod for fixing the electrode 25, and 24 is a bolt for connecting an insulating wire connected to a secondary circuit (not shown). In the switchgear voltage detection device of the present embodiment configured as described above, the electrodes 25 are provided with circumferential irregularities or linear irregularities on the surface facing the main circuit conductor 11, so that it is apparent. The area of the electrode 25 is increased, and the capacitance between the main circuit conductor 11 and the electrode 25 is increased.

Therefore, with the electrode 25 having a smaller outer diameter, a capacitance equivalent to that of a smooth disk electrode can be obtained. As a result, the electrode 25 can be downsized, that is, the secondary circuit can be downsized, and the electric field strength distribution with the main circuit conductor 11 is not disturbed, and the insulation performance can be improved.

As described above, in this embodiment, the electrode 25 is provided so as to face the main circuit conductor 11, and the electrode 2
5, a guard electrode 17 is provided on the outer periphery of the switch gear 5 to form a capacitance, and the voltage is divided by the impedance of the secondary circuit.
By providing circumferential irregularities or linear irregularities on the surface opposite to, the apparent area of the electrode 25 is increased, and the electrostatic capacitance between the main circuit conductor 11 and the electrode 25 is increased. The outer diameter of the electrode 25 for obtaining the same capacitance can be small.

As a result, the size of the secondary circuit can be reduced. The present invention is not limited to the above embodiments, but can be implemented in the same manner as described below.

(A) In each of the above embodiments, even if the insulating gas is changed from SF ₆ gas to air, the dielectric constant is about 1
Since it is almost the same as the above, the same effects as those in the case described above can be obtained with respect to protection from the guard electrode 17 and surge voltage, increase in electrostatic capacity, and the like. However, in this case, since the dielectric strength is different, the insulation distance is changed and the capacitance with the main circuit conductor 11 is changed.

Further, even in oil-insulated equipment, although the dielectric constant increases and the capacitance of the unit electrode area changes,
The same effect as the above case can be obtained. (B) In the third embodiment, the electrode 25 is the main circuit conductor 1
The case where the circumferentially-shaped unevenness or the linearly-shaped unevenness is provided on the surface facing 1 has been described, but the invention is not limited to this.
Even if irregularities having other predetermined shapes are provided, the same effect as the above case can be obtained.

[0053]

As described above, according to the inventions corresponding to the first and second aspects, the electrode is provided so as to face the main circuit conductor to form the capacitance, and the impedance of the secondary circuit is formed. In a switchgear voltage detection device that divides voltage with and, a guard electrode (guard electrode whose step with the electrode can be adjusted) is provided on the outer peripheral portion of the electrode so that it is set to the ground potential. It is possible to provide a switchgear voltage detection device capable of adjusting the capacitance on the high voltage side to fix the capacitance of the secondary circuit and adjusting the output voltage for stabilization.

According to the invention corresponding to claim 3,
In addition to providing an electrode facing the main circuit conductor, a guard electrode is provided on the outer periphery of the electrode to form an electrostatic capacitance, and the guard electrode is used as a guard electrode in the voltage detection device of the switchgear that divides voltage by the impedance of the secondary circuit. Since the protrusion is provided, it is possible to provide a switchgear voltage detection device capable of preventing the surge voltage from entering the secondary circuit and protecting the secondary circuit.

Further, according to the invention corresponding to claim 4, an electrode is provided so as to face the main circuit conductor, and a guard electrode is provided on an outer peripheral portion of the electrode to form an electrostatic capacitance, thereby forming a secondary circuit. In the voltage detection device of the switchgear that divides the voltage with the impedance, the electrode is provided with an insulating layer made of an insulating material at the portion facing the main circuit conductor.
A voltage detector for a switchgear capable of protecting the secondary circuit by preventing the surge voltage from entering the secondary circuit.

Further, according to the inventions corresponding to claims 5 to 7, an electrode is provided so as to face the main circuit conductor, and a guard electrode is provided on an outer peripheral portion of the electrode to form a capacitance. In a switchgear voltage detection device that divides voltage with the impedance of the secondary circuit, the electrode should have irregularities (circular irregularities or linear irregularities) on the surface facing the main circuit conductor. As a result, it is possible to provide a switchgear voltage detection device capable of reducing the size of the secondary circuit.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a first embodiment of a switchgear voltage detection device according to the present invention.

FIG. 2 is a partially enlarged sectional view showing a second embodiment of the switchgear voltage detection device according to the present invention.

FIG. 3 is a partially enlarged cross-sectional view showing a third embodiment of the switchgear voltage detection device according to the present invention.

FIG. 4 is a side view showing a configuration example of a switchgear.

FIG. 5 is a diagram showing an equivalent circuit of a switchgear voltage detection device.

FIG. 6 is a characteristic diagram showing a relationship between an output voltage obtained by an experiment and a height of a guard electrode in a switchgear voltage detection device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Box body, 2 ... Partition wall, 3 ... Circuit breaker, 4 ... Disconnector, 5 ... Busbar, 6 ... Insulator, 7 ... Cable head, 8 ... Connection conductor, 9 ... Insulating spacer, 10 ... Electrode, 11 ... Main circuit Conductor, 12 ... Electrode, 13 ... Bolt, 14 ... Insulation wire, 15 ... Board wall, 16 ... Insulation rod, 17 ... Guard electrode, 18a, 18b ... Fixing rod, 19 ... Bolt, 20 ... Projection, 21 ... Electrode, 22 ... Insulating layer, 23 ... Insulating rod, 24 ... Bolt, 25 ... Electrode.

Claims (7)

[Claims] 1. A switchgear voltage detection device in which an electrode is provided so as to face a main circuit conductor to form a capacitance, and a voltage is divided by the impedance of a secondary circuit. A switchgear voltage detection device, characterized in that it is provided with a guard electrode and is provided with a ground potential. 2. The switch gear voltage detection device according to claim 1, wherein the guard electrode is provided with a guard electrode whose step difference from the electrode can be adjusted. 3. A switchgear voltage detecting device for providing an electrode facing a main circuit conductor, and providing a guard electrode on an outer peripheral portion of the electrode to form an electrostatic capacitance, and performing voltage division with impedance of a secondary circuit. 3. The switchgear voltage detection device according to claim 1, wherein the guard electrode is provided with a protrusion. 4. A voltage detecting device for a switchgear, wherein an electrode is provided so as to face a main circuit conductor, and a guard electrode is provided on an outer peripheral portion of the electrode to form an electrostatic capacitance, which is divided by impedance of a secondary circuit. The switchgear voltage detection device according to claim 1, wherein an insulating layer made of an insulating material is provided in a portion where the electrode faces the main circuit conductor. 5. A voltage detecting device for a switchgear, wherein an electrode is provided so as to face a main circuit conductor, and a guard electrode is provided on an outer peripheral portion of the electrode to form an electrostatic capacitance, and a voltage is divided by impedance of a secondary circuit. 3. The switchgear voltage detection device according to claim 1, wherein the electrode is provided with irregularities of a predetermined shape on the surface facing the main circuit conductor. 6. The voltage detecting device for a switch gear according to claim 5, wherein the irregularities are circumferential irregularities. 7. The voltage detection device for a switch gear according to claim 5, wherein the irregularities are linear irregularities.