JP2012156117A - Vacuum insulated switch and vacuum insulated switchgear - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vacuum insulated switch including a function diagnosing soundness of vacuum pressure during a continuous operation without causing power interruption in inspection.SOLUTION: A vacuum insulated switch according to the present invention includes: a vacuum valve 1 closing and interrupting current while an inside of the vacuum valve is vacuum; an intermediate shield 5 arranged within the vacuum valve 1; and a vacuum measuring terminal 12 having at least a part of a face where a closest opposing distance relative to the intermediate shield 5 is approximately constant.

Description

  The present invention relates to a vacuum insulation switch and a vacuum insulation switchgear, and more particularly to a vacuum switch and a vacuum insulation switchgear suitable for a device equipped with a measuring device for measuring the vacuum pressure in a vacuum vessel.

  A vacuum insulated switch is a device that energizes and interrupts current, and is a device that is mainly disposed in a power distribution system. The vacuum insulation switchgear refers to a composite of a switch including a ground switch and the like in addition to a vacuum insulation switch. When performing vacuum insulation, since the dielectric strength depends on the vacuum pressure, it is desirable to monitor the vacuum pressure in the vacuum insulation switch.

  Here, as a technique for monitoring the vacuum pressure, for example, there is one described in Patent Document 1. In Patent Document 1, a conductive terminal is placed around a metal vacuum vessel via an insulator, and the potential generated at the conductive terminal is measured to determine whether the vacuum pressure in the vacuum vessel is healthy. Deciding.

JP 2007-080594 A

  However, in the method described in Patent Document 1, the terminals are point-shaped, and in order to measure the potential by forming a capacitor, the area for forming the capacitor is small, and the measured value may fluctuate. There was room for improvement in terms of improvement.

  Therefore, an object of the present invention is to provide a vacuum insulated switch or vacuum insulated switchgear that improves the accuracy of vacuum pressure diagnosis.

  In order to achieve the above object, in the vacuum insulated switch according to the present invention, the inside is a vacuum, a vacuum valve for supplying and shutting off current, a shield disposed in the vacuum valve, and a shield closest to the shield. A vacuum measurement terminal having at least a part of a surface having a substantially constant facing distance is provided.

  The vacuum insulated switchgear according to the present invention includes the vacuum switch and an air-insulated ground disconnecting part having a circuit grounding / disconnecting function.

  According to the present invention, it is possible to improve the accuracy of vacuum pressure diagnosis.

(A) It is an upper cross-sectional view of the mold part of the vacuum switchgear according to the first embodiment. (B) It is a cross-sectional view of the mold part of the vacuum switchgear of Example 1. (A) It is the schematic of the vacuum valve and vacuum sensor terminal of Example 1, and is the figure seen from the upper surface. (B) It is the schematic of the vacuum valve and vacuum sensor terminal of Example 1, and is the figure seen from the front. 1 is a wiring diagram of a pressure diagnostic apparatus according to Embodiment 1. FIG. It is a characteristic view (Paschen curve) showing the relationship between a pressure and a discharge start voltage. It is a wiring diagram of the pressure diagnostic apparatus of Example 2. It is a cross-sectional view of the mold part of the vacuum switchgear of Example 3.

  In the following, preferred embodiments of the present invention will be described with reference to the drawings. In addition, it is needless to say that the following examples are merely examples of implementation and the present invention is not intended to be limited to the specific modes of the examples.

  A first embodiment will be described with reference to FIGS. As shown in FIG. 1 (a), the vacuum insulated switchgear according to this embodiment includes a vacuum valve 1 (corresponding to a vacuum insulated switch), an air-insulated ground disconnecting portion 25, and a plurality of these switches. It is roughly composed of an insulating material 13 such as an epoxy which is insulation molded. A conductive coating 14 having a ground potential is applied to the surface of the insulator 13 so that no electric shock is caused even if it is contacted.

  As shown in FIG. 1 (b), the vacuum valve 1 penetrates the fixed side ceramic tube 2, the fixed side terminal plate 3 that covers and covers the end of the fixed side ceramic tube 2, and the fixed side terminal plate 3. A stationary conductor 4 passing inside and outside the vacuum vessel, an intermediate shield 5 disposed around the stationary electrode 11 and the movable electrode 15 in the vacuum valve 1, and a movable ceramic tube 6 joined to the stationary ceramic tube 2; , A movable side terminal plate 7 that covers and covers the end of the movable side ceramic cylinder 6; a movable conductor 8 that passes through the movable side terminal plate 7 and passes inside and outside the vacuum vessel; The bellows for operating the movable conductor 8 by the operating force from the operating device, the fixed electrode 11 provided at the tip of the fixed conductor 4, the fixed electrode 11 and the movable conductor 8 Movable electrode 1 provided at the tip It is composed of a. The movable electrode 15 is operable by the bellows while maintaining a vacuum hermeticity, and opens and closes the current by contacting and leaving the fixed electrode 11. The fixed conductor 4 is connected to a load connection conductor 9, and the load connection conductor 9 is connected to the load side via a cable or the like. The insulator 13 also covers the periphery of the load connection conductor 9, and the load connection bushing 17 is formed by the load connection conductor 17 and the insulator 13 covering the periphery thereof.

  The air-insulated ground disconnection portion 25 includes a bushing-side fixed electrode 31 formed integrally with the bus-bar connecting conductor 10 connected to the bus-side, and an intermediate air that can slide and contact the bushing-side fixed electrode 31. A contact 30 and an intermediate air contact 30 are provided. The air movable conductor 33 is driven in the vertical direction in FIG. On the same axis as the ground air contact 29 provided, the intermediate fixed electrode 34 electrically connected to the movable side of the vacuum valve 1 via the flexible conductor 22, the bushing side fixed electrode 31 and the intermediate fixed electrode 34 The ground-side fixed electrode 32 fixed to the metal housing 28 that is positioned and covers the opening of the insulator 13 is connected to the operating unit side of the air movable conductor 33, and is operated by the air movable conductor 33. Operating force from the vessel Composed of earthing and disconnecting switch for the insulating rod 24 that reach. The intermediate air contact 30 is formed to be able to slide and contact the bushing side fixed electrode 31 and the intermediate fixed electrode 34 and the ground air contact 29 to the ground side fixed electrode 32 and the intermediate fixed electrode 34, respectively. ing. The insulator 13 also covers the periphery of the busbar connection conductor 10, and the busbar connection bushing 16 is formed by the busbar connection conductor 16 and the insulator 13 covering the periphery thereof.

  The vacuum valve 1 is opened and closed by a vacuum valve insulating rod 23, and the air-insulated ground disconnecting portion 25 is opened and closed by a ground disconnecting portion insulating rod 24. The air-insulated ground disconnection portion 25 has a structure that can be switched to three positions: closed, disconnection, and ground.

  In this embodiment, as shown in FIGS. 1A and 1B and FIGS. 2A and 2B, a vacuum measuring terminal 12 for vacuum pressure diagnosis is disposed around the vacuum valve 1, and the vacuum is measured. The measurement terminal 12 is provided with a measurement terminal voltage detector 18 connected to the pressure diagnostic device 19 side shown in FIG. In the present embodiment, the vacuum measurement terminal 12 and the measurement terminal voltage detector 18 are covered with an insulator 13 as shown in FIG. The vacuum measuring terminal 12 and the conductive coating 14 are not in direct contact with each other, and both are electrically insulated.

As shown in FIG. 3, the pressure diagnostic device 19 includes a capacitor 26 having one end connected to the measurement terminal voltage detection unit 18 and the other end set to the ground potential, and a capacitance C ₀ , and the capacitor 26 The voltmeter 20 that measures the voltage V _out at both ends of the voltmeter and a determination unit 21 that is connected to the voltmeter 20 and determines whether the vacuum pressure in the vacuum valve 1 is in a normal range. The vacuum measurement terminal 12 is connected to the other end of the capacitor 26 whose one end is grounded, and the voltmeter 20 measures the voltage _Vout generated at both ends of the capacitor 26. The determination unit 21 compares a predetermined reference value with a measurement value measured by the voltmeter 20. When the reference value exceeds the reference value, the determination unit 21 determines that the pressure is equal to or higher than the vacuum pressure, and when the reference value is below the reference value. Determines that the vacuum pressure is normal.

Here, the vacuum measurement terminal 12 and the intermediate shield 5 are arranged via an insulator to form a capacitor (the capacitance of the capacitor is C ₁ ), but the vacuum measurement terminal In order to obtain an area sufficient to ensure a sufficient capacitance C ₁ between the intermediate shield 5 and the intermediate shield 5, as shown in FIG. 2 (a), the vacuum measurement terminal 12 has the intermediate shield 5 and the center O substantially equal, The intermediate shield 5 has a shape that covers at least a part of the outer peripheral side in a substantially concentric manner. The vacuum measurement terminal 12 has a substantially equal center with the intermediate shield 5 and covers at least a part of the outer peripheral side in a substantially concentric manner, so that the distance between the intermediate shield 5 and the vacuum measurement terminal 12 is equal. 5 and the vacuum measuring terminal 12 can be formed in a planar shape, so that an electric field can be evenly distributed between the intermediate shield 5 and the vacuum measuring terminal 12. “Substantially constant” means that there is a constant relationship between the measurement terminal and the shield so that the measurement accuracy of the potential is improved.

  Here, when the vacuum measurement terminal 12 and the measurement terminal voltage detection unit 18 are molded with an insulator as in the present embodiment, it is desirable that the vacuum measurement terminal 12 and the measurement terminal voltage detection unit 18 be formed from a metal with good workability, such as brass or aluminum.

  Here, the vacuum measurement terminal 12 is molded with the insulator 13, but the measurement terminal voltage detection unit 18 is exposed and connected to an external pressure diagnostic device 19. When the vacuum measuring terminal 12 is molded with the insulator 13, it is attached in advance to a mold filled with the insulator 13, and is removed from the mold together with the insulator 13 after molding so that the vacuum measurement terminal 12 can be accurately positioned. Embedding can be realized. In this embodiment, the measurement terminal voltage detector 18 is exposed. However, the exposure is not an indispensable condition for achieving the effect of the invention, and the voltage of the pressure diagnostic device 19 in this embodiment is measured. A part or the whole may be molded as long as it can be electrically connected to the device. Conversely, the vacuum measurement terminal 12 is not necessarily embedded in the mold for vacuum measurement.

Next, an operation for determining whether the vacuum pressure is normal or abnormal will be described. The vacuum measuring terminal 12 and the intermediate shield 5 form a capacitor having a capacitance C ₁ , and the capacitor is connected in series with a capacitor 26 in the pressure diagnostic device 19. Thus, the voltage V _out across the capacitor 26 will depend on the voltage applied to the capacitor of the capacitance C _1. As shown in FIG. 4, the discharge characteristic in vacuum is a Paschen curve indicating the relationship between the pressure and the discharge start voltage. Therefore, the main circuit (in the vacuum bulb 1, the fixed conductor 4, the fixed electrode 11, the movable conductor). 8, the same applies to the movable electrode 15. The same applies hereinafter) and the intermediate shield 5, and when the pressure rises above a certain value, a discharge occurs between the main circuit and the intermediate shield 5, and the intermediate The potential V _{1 of the} shield 5 rises. Therefore, if the capacitances C ₀ and C ₁ are grasped in advance, the potential V ₁ of the intermediate shield 5 can be calculated from the voltage V _out across the capacitor 26, and the potential (or a variable that varies depending on the potential) can be calculated. From, for example, V _out ), it can be determined whether the vacuum pressure is normal.

Here, the capacitance C ₁ between the vacuum measurement terminal 12 and the intermediate shield 5 is set to a specified value by determining the shape of the vacuum measurement terminal 12 and the distance between the vacuum measurement terminal 12 and the intermediate shield 5 in advance. be able to. Thus, the capacitance C ₁ value between the vacuum measurement terminal 12 and the intermediate shield 5 is important in determining whether the vacuum pressure is normal, and it is necessary that it does not vary from the specified value.

Here, the output voltage V _out as described above, will be determined by the ratio of the capacitance C ₁ between the electrostatic capacitance C ₀ and vacuum measurement terminal 12 intermediate the shield 5 of the capacitor 26, the potential of the intermediate shield 5 Since the potential of V ₁ and the other end side of the capacitor 26 connected to the measurement terminal voltage detector 18 is the ground potential (0 V), it can be calculated as follows.

V _out = V ₁ × C ₁ / (C ₁ + C ₀ )
At this time, as described above, C ₀ and C ₁ are set in advance so that the voltage V _out falls within the detection range of the pressure diagnostic device 19.

That is, since C ₀ and C ₁ are known constants, it is possible to calculate the potential V ₁ of the intermediate shield 5 by measuring the voltage V _out . As described above, the voltage V ₁ changes depending on the pressure in the vacuum valve 1 and rises when the vacuum pressure is abnormal and discharge occurs. From the voltage V ₁ or the voltage V _out value, etc. It becomes possible to diagnose the soundness of the vacuum pressure of the vacuum switchgear.

In the present embodiment, the vacuum measurement terminal 12 has a shape that is substantially equal to the center of the intermediate shield 5 and covers at least a part of the outer peripheral side of the intermediate shield 5 in a substantially concentric shape, so that the intermediate shield 5 and the vacuum measurement terminal 12 are covered. Can be formed in a planar shape, the capacitance C ₁ is less likely to fluctuate, and the size of the capacitance can be freely changed by changing the area facing the intermediate shield 5. It becomes possible (because it can be set to a value that increases the S / N ratio), and the accuracy of the vacuum pressure diagnosis is improved. As a result, the capacitance value can be freely designed so that the voltage _Vout falls within the detection range of the pressure diagnostic device 19.

Further, in the present embodiment, the intermediate shield 5 is formed in a cylindrical shape in accordance with the cylindrical vacuum valve 1, so that the vacuum measurement terminal 12 is also covered in a substantially concentric shape. If a part of the surface where the closest facing distance between the vacuum measuring terminal and the vacuum measuring terminal is substantially constant is provided, a capacitor can be formed between the facing surfaces, and the capacitance C ₁ is less likely to fluctuate. A certain effect can be obtained in that the size of the capacitance can be freely changed by changing the facing area.

  As a case having such a feature, it is conceivable that at least a part of the intermediate shield and the vacuum measurement terminal have a similar shape so that the facing distance between the two is substantially constant. In this case, the capacitance of the capacitors formed between the opposing surfaces can be made more stable, and the closest opposing distance between the intermediate shield and the vacuum measurement terminal is substantially constant with respect to the intermediate shield. This is useful compared to the case where some aspects of

  Further, among the cases where the intermediate shield and the vacuum measurement terminal (at least a part of them) have a similar shape and the opposing distance between them is substantially constant, the intermediate shield 5 is a cylinder as in this embodiment. The shape of the vacuum measuring terminal 12 is substantially equal to the center of the intermediate shield 5 and the outer periphery of the intermediate shield 5 is covered in a substantially concentric shape so that corners can be eliminated. It is possible to alleviate the electric field concentration, which is more useful.

  In this embodiment, the intermediate shield 5 is mainly described as an arc shield for preventing the arc from adhering to the insulating cylinder. However, the arc shield is used when a discharge occurs due to vacuum deterioration. Regardless of whether or not it is discharged and conducted everywhere in the vacuum bulb, any shield can be used as long as it exists in the vacuum bulb 1, and it can be applied to all conductive members.

  Example 2 will be described with reference to FIG. In the present embodiment, the case where the vacuum insulated switchgear described in the first embodiment is arranged in three phases will be described. However, the individual vacuum insulated switchgear is the same as that of the first embodiment, and redundant description is omitted.

In this embodiment, as shown in FIG. 5, the measurement terminal voltage detector 18 to which the voltage of the vacuum measurement terminal 12 for three phases is applied is synthesized at the connection point 27, and the synthesized voltage is applied to the ground side of the capacitor 26. One end to be connected is applied to the other end side. Therefore, the detected output voltage _Vout is a value proportional to the combined value of the voltages generated at the measurement terminals for three phases.

  According to the contents described in the first embodiment, it is possible to diagnose the soundness of the vacuum pressure of the vacuum insulated switchgear, but the potential induced in the intermediate shield is about 40% of the main circuit, which is higher than the conventional value. Furthermore, since the potential fluctuates depending on the contact state (on / off), the S / N ratio tends to decrease. Therefore, in this embodiment, by combining and inputting signals for three phases as shown in FIG. 5 to the detector for judging the vacuum pressure abnormality, random noise is canceled and the S / N ratio is set. It is further improved. For example, the vacuum leak of the vacuum vessel is monitored by setting the signal to zero when the degree of vacuum is normal and generating a signal when an abnormality occurs in any phase and the three-phase imbalance occurs. Can do. It is only necessary to adjust each electrostatic capacity for the normal voltage and the abnormal voltage, and the electric potential does not have to be changed from zero during normal operation to zero during normal operation.

  In the present embodiment, the case where the measurement terminal voltage detectors 18 for three phases are combined at one connection point 27 is described. However, a plurality of connection points are provided to synthesize voltages step by step. May be. Even if only two phases are synthesized without synthesizing all three phases, there is a certain effect in improving the S / N ratio.

  In order to check whether the vacuum measurement terminal 12 operates normally, an AC withstand voltage test, which is a routine test before product shipment, is used. Since the vacuum measurement terminal 12 generates a signal when the combined voltage of the three phases becomes unbalanced, it is confirmed that the vacuum measurement terminal 12 is operating normally by performing an AC voltage application test on each phase. be able to. Conventionally, the inspection of the vacuum measurement terminal 12 and the AC withstand voltage test have been performed separately. However, in this method, the inspection of the vacuum measurement terminal 12 and the AC withstand voltage test can be performed simultaneously. Items and time can be shortened.

  A third embodiment of the present invention will be described with reference to FIG. In FIG. 6, the disconnection state of the vacuum switchgear described in each of the above embodiments will be described. Other than that, it is the same as described above, and redundant explanation is omitted here.

  In this embodiment, the disconnection state is such that the distance between the intermediate air contact 30 of the air insulated ground disconnection portion 25 and the bushing side fixed electrode 31 is the ground air contact 29 of the air insulated ground disconnection portion 25 and the ground side fixed electrode. The distance is made larger than the distance to 32. Further, the contact on the vacuum valve 1 side in the disconnected state is also set to the cutoff position, thereby improving the reliability of the disconnected state. The ground-side fixed electrode 32 is connected to the metal housing 28 having the ground potential as described in the first embodiment.

  With such a configuration, even when an abnormality such as a lightning strike occurs on the load side, since the vacuum valve 1 side is in the shut-off position, the abnormality does not spill over to the bus side, and the reliability can be improved. .

  Also, if a vacuum leak occurs, the interrupted state in the vacuum valve 1 is broken, the contacts are connected, and an abnormal potential on the load side is applied to the air movable conductor 33. Even so, the distance between the intermediate air contact 30 of the air insulated ground disconnecting portion 25 and the bushing side fixed electrode 31 is the distance between the air contact 29 for grounding of the air insulating ground disconnecting portion 25 and the grounded fixed electrode 32. Since it is larger in comparison, the intermediate air contact 30 of the air movable conductor 33 and the bushing side fixed electrode 31 are not electrically connected, and the air contact for grounding of the air movable conductor 33 having a low dielectric strength is provided. 29 and the ground side fixed electrode 32 are electrically connected. Therefore, a ground fault priority structure can be obtained without causing an abnormality to propagate to the busbar side. If the abnormality spreads to the bus side, the abnormality spreads to other circuits, so that the abnormality of one circuit on the load side is diffused. Therefore, it is possible to improve the reliability of the power system itself by adopting the ground fault priority structure without causing abnormality on the bus side as described above.

  It should be noted that the points according to the present embodiment are not necessarily used together with the vacuum pressure diagnosis in each of the above embodiments, and can be applied to switches and switch gears that do not perform the vacuum pressure diagnosis.

DESCRIPTION OF SYMBOLS 1 Vacuum valve 2 Fixed side ceramic cylinder 3 Fixed side terminal board 4 Fixed conductor 5 Intermediate shield 6 Movable side ceramic cylinder 7 Movable side terminal board 8 Movable conductor 9 Load connection conductor 10 Busbar connection conductor 11 Fixed electrode 12 Vacuum measurement terminal 13 Insulator 14 Conductive coating 15 Movable electrode 16 Busbar connection bushing 17 Load connection bushing 18 Measuring terminal voltage detection unit 19 Pressure diagnostic device 20 Voltmeter 21 Determination unit 22 Flexible conductor 23 Insulation rod for vacuum valve 24 Insulation rod for ground disconnection 25 Air-insulated ground disconnection part 26 Capacitor 27 Connection point 28 Metal housing 29 Air contact for grounding 30 Intermediate air contact 31 Bushing side fixed electrode 32 Ground side fixed electrode 33 Air movable conductor 34 Intermediate fixed electrode

Claims (7)

  A vacuum valve for supplying and shutting off current when the inside is vacuum, a shield disposed in the vacuum valve, and a vacuum measurement terminal having at least a part of a surface where the distance between the shield and the closest point is substantially constant A vacuum insulation switch characterized by   2. The vacuum insulated switch according to claim 1, wherein the shield and the vacuum measurement terminal have at least a part of a similar shape, and a distance between the shield and the vacuum measurement terminal in the similar shape part. Is a vacuum insulated switch characterized by being substantially constant.   3. The vacuum insulated switch according to claim 2, wherein the shield has a cylindrical shape, the vacuum measurement terminal has a center substantially equal to the shield, and at least a part of an outer peripheral side of the shield is substantially concentric. A vacuum-insulated switch characterized by having a shape covering the shape.   The vacuum insulated switch according to any one of claims 1 to 3, wherein the voltage applied to the vacuum measurement terminal is synthesized between different phases.   5. The vacuum insulated switch according to claim 4, wherein the voltage applied to the vacuum measuring terminal is synthesized in a three-phase manner.   A vacuum insulated switchgear comprising the vacuum insulated switch according to any one of claims 1 to 5 and an air insulated ground disconnecting part having a circuit grounding / disconnecting function. 7. The switchgear according to claim 6, wherein the air-insulated ground disconnecting portion is connected to a movable conductor, an intermediate air contact and a ground air contact provided on the movable conductor, and a bus-side bushing. A bushing-side fixed electrode, and a ground-side fixed electrode that is at the ground potential and is in contact with and away from the ground air contact,
A vacuum insulated switchgear characterized in that, in a disconnected state, a distance between the intermediate air contact and the bushing side fixed electrode is larger than a distance between the ground air contact and the ground side fixed electrode.

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