JPH0133014B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vacuum degree monitoring device for a vacuum shearing device.

In general, the capacity of a vacuum chamber or disconnector is greatly affected by the quality of the internal vacuum, so it is necessary to monitor the vacuum. For this reason, various vacuum degree monitoring devices have been proposed in the past, but all of them have problems with insulation, size, cost, etc., and are not practical.

The present invention eliminates the above-mentioned conventional drawbacks, has a simple configuration, is small, inexpensive, has no insulation problems, can constantly monitor the degree of vacuum with high sensitivity and high reliability, and is easy to install. The purpose of this invention is to provide a vacuum level monitoring device.

First, the basic idea of the present invention is shown in Figure 1A.
This will be explained with reference to FIG. 2 and FIGS. 3A and 3B. 1A and 1B respectively show a vacuum shield breaker and its equivalent circuit in the energized state, where 1 is a fixed electrode, 2 is a movable electrode, 3 is a fixed lead, 4 is a movable lead, 5 is an insulating cylinder, 6, Reference numeral 7 denotes an end plate sealed to both ends of the insulating cylinder 5, the fixed lead 3 is attached to the end plate 6, and the movable lead 4 is attached to the end plate 7 via a bellows 8.
is sealed. 9 is a shield attached to the middle of the insulating cylinder 5. Further, 10 and 11 are the power supply and load of the circuit in which the vacuum shield and circuit breaker are installed, respectively, 12,
13 is the resistance and capacitance between the fixed electrode 1 and the shield 9, 14 and 15 are the resistance and capacitance between the movable electrode 2 and the shield 9, respectively, 16a and 16b
is the resistance of the insulating tube 5, and 17 is the capacitance between the shield 9 and the ground potential.

In the vacuum chamber disconnector described above, the inside of the vacuum container formed by the insulating cylinder 5 and the end plates 6 and 7 is maintained at a high vacuum, and when this degree of vacuum deteriorates, the capacitance 13 , 15 does not change because the dielectric constant in the atmosphere is almost equal to the vacuum dielectric constant, but the resistance 1
2 and 14 suddenly become smaller. For this reason, the voltage between the electrodes 1, 2 and the shield 9 becomes small, and the voltages shared at each part of the vacuum shield and disconnector change. For example, when the degree of vacuum is good, the voltage of the power supply 10 is V, the voltage between the fixed electrode 1 and the shield 9 is V ₁ , the voltage between the movable electrode 2 and the shield 9 is V ₂ , and the voltage between the shield 9 and the earth potential Let V ₃ be V ₁ = V ₂ =
V/2, V ₃ = V-V ₁ = V/2, but if the degree of vacuum deteriorates, V ₁ = V ₂ = V/4, V ₃ = V-V/4 = 3/4 V. (Please note that these values are shown as just an example, and the structure of the shingle breaker changes depending on the degree of vacuum.) Therefore, as shown in FIG. 2, the voltage V ₃ of the shield 9 changes greatly depending on the degree of vacuum, and the electric field E on the outer peripheral side of the shield 9 also changes greatly.

Moreover, FIGS. 3A and 3B show the vacuum shield disconnector and its equivalent circuit in the disconnected state, respectively, and 18 and 1
9 indicates the resistance and capacitance between electrodes 1 and 2, respectively. In this case as well, the capacitances 13, 15, 19 do not change depending on the degree of vacuum, but the resistances 12, 14, 18
varies depending on the degree of vacuum. Therefore, when the degree of vacuum deteriorates, the voltage across the shield 9 increases and the electric field on the outer circumferential side of the shield 9 also increases.

As described above, in the vacuum shield breaker, the potential of the shield 9 changes greatly depending on the degree of vacuum, whether in the energized state or the energized state, and the electric field on the outer circumferential side of the shield 9 also changes greatly. Additionally, along with this, the electric field on the outer circumferential side of the vacuum chamber and disconnector also changes overall. Therefore, by monitoring the electric field on the outer circumferential side of the vacuum shield or disconnector, the degree of vacuum of the vacuum shield or disconnector can be constantly monitored.

Embodiments of the present invention will be described below with reference to the drawings. 4A, B, and C show a first embodiment of the present invention,
A tank 21 is supported horizontally on the support legs 20, and a vacuum shield breaker 26 is supported horizontally within the tank 21 via insulating materials 22, 23 and conductive members 24, 25. Further, a pair of mounting seats 21a are provided in the upper part of the tank 21 in the length direction, and a pair of bushings 27 are attached to each mounting seat 21a. A large diameter portion 27a is provided at the bottom of each bushing 27.
are formed, and a current transformer 28 is built in each of the large diameter portions 27a. Further, a terminal 29 is provided at the upper end of each bushing 27, and in order to maintain an insulation distance L between the terminals 29, each bushing 27 is provided inclined in opposite directions. Further, the conductors 30 connecting between the conductive members 24 and 25 and the terminals 29 are connected to the bushings 27.
The tank 21 and the bushing 27
The inside is filled with an insulating fluid 31 such as SF ₆ gas, Freon gas, or insulating oil.

In the tank-type vacuum shearing device configured as described above, a hole 21b is provided in the lower part of the tank 21 in a portion of the vacuum shearing cutter 26 facing the shield 9, and the edge of the hole 21b is made to protrude outward. A flange portion 21c is formed, and the first case 33 is sealed and fastened to the flange portion 21c with bolts 34 via an O-ring 32. The first case 33 is made of an insulating material such as epoxy resin, and the tank 2
The shape is concave to the inside of 1. Second case 3
5 is also formed of an insulating material such as epoxy resin and has a shape concave toward the inside of the tank 21.
The case 35 is housed within the first case 33 with a gap 36 therebetween, and is hermetically fastened to the outside of the first case 33 with a bolt 37 via an O-ring 32'. The detection unit housing 38 is also made of an insulating material such as plastic, and inside thereof is an electro-optical effect element 39 (consisting of a Pockels element, a Kerr element, a field effect type (DAP) or a torsional effect type (TN) liquid crystal, etc., hereinafter referred to as the element). A detection unit consisting of a polarizer 40 and an analyzer 41 is hermetically housed, and each of the polarizer 40 and the analyzer 41 is equipped with an optical fiber 4.
Connect one end of 2,43. Detector housing 3
8 is arranged at the innermost part inside the second case 35, and the second
An insulating molding material 44 such as liquid cast-cured rubber (silicon, polybutadiene, epoxy, etc.) is injected into the case 35 and solidified to form the sensor housing 3.
Fix 8. A recess 44 a is formed in the center of the insulating mold material 44 . metal cover 45
covers the outside of each case 33, 35 and has a recess 45a that fits into the recess 44a;
and flange portion 33 of second case 33, 35
a, 35a and the bolt 3 inserted through the cover 45
7 to the flange portion 21c of the tank 21, the cover 45 is fixed to the second case 35 and the outer surface of the insulating mold material 44 by pressure. Further, since the cover 45 is connected to the tank 21 which is at ground potential via the bolt 37, the cover 45 is also at ground potential. The second case 35 is provided with an insulating fluid injection pipe 46 that closely penetrates the injection pipe 4.
6 also penetrates the cover 45, and after the space 36 is evacuated through this injection pipe 46, an insulating fluid such as SF ₆ gas or insulating oil is injected, and the injection pipe 46 is sealed with a cap 47. The optical fibers 42 and 43 are inserted through the cover 45 and led out to the outside, and the optical fiber 42 has a light emitting section 4 at its tip.
8, and a light receiving section 4 is provided at the tip of the optical fiber 43.
9 will be provided. Further, a vacuum degree determination section 50 for determining whether the degree of vacuum is good or bad is electrically connected to the light receiving section 49.

The operation of the vacuum level monitoring device described above will be explained using FIG. 5. Light emitted from the light emitting section 48 is sent to the polarizer 40 via the optical fiber 42, and is linearly polarized in the horizontal or vertical direction. . Element 3
Reference numeral 9 applies an electric field E to the outer circumferential side of the vacuum shield breaker 26, particularly the outer circumferential side of the shield 9, in the horizontal or vertical direction, and rotates the polarization plane of the light from the polarizer 40 by an angle θ according to the electric field E. . Next, the light that has passed through the element 39 is applied to an analyzer 41 having a polarization plane that has a predetermined relationship with the polarization plane of the polarizer 40, and the light that has passed through the analyzer 41 is applied to the analyzer 41 via an optical fiber 43 according to the amount of light. It is added to a light receiving section 49 that outputs an electrical signal. As shown in FIG. 6, when the degree of vacuum in the vacuum chamber and disconnector 26 is good, the electric field E applied to the element 39 is small, and when the degree of vacuum becomes poor, the electric field E increases.
Therefore, the rotation angle θ of the plane of polarization of the light in the element 39
is small when the degree of vacuum is good, and becomes large when the degree of vacuum is poor. Therefore, when the polarization planes of the polarizer 40 and the analyzer 41 are at right angles, if the degree of vacuum becomes poor, the amount of light passing through the analyzer 41 will increase, and the output A of the light receiving section 49 will be as shown by the solid line in FIG. becomes larger. Moreover, a polarizer 40 and an analyzer 4
When the polarization planes 1 and 1 are parallel, if the degree of vacuum is poor, the amount of light passing through the analyzer 41 decreases, and the light receiving section 49
The output A becomes smaller as shown by the dotted line in FIG. For this reason, the degree of vacuum quality determination section 50 detects deterioration of the degree of vacuum due to a sudden change in the output A, and outputs an output for an alarm or display.

By the way, since the tank 21 is filled with an insulating fluid 31 having a small dielectric constant (ε _S ) and high dielectric strength (ε _S ≒1 for SE ₆ and Freon, and ε _S ≒2 for insulating oil), a vacuum is generated. The distance between the shield breaker 26 and the tank 21 has become smaller. Therefore, the capacitance 17 between the shield 9 and the tank 21 at ground potential becomes large due to the small distance therebetween and the large opposing area, and the potential of the shield 9 becomes small especially when the degree of vacuum is good. Therefore, the potential change of the shield 9 increases when the degree of vacuum deteriorates, and the electric field change between the shield 9 and the tank 21 also increases. Therefore, the detection sensitivity of the electric field change of the element 39 is improved. FIG. 7 is an explanatory diagram of the above. When the distance between the shield 9 and the ground potential is large, the voltage characteristics are shown by the solid line A when the degree of vacuum is good, and by the dotted line B when the degree of vacuum is poor. 9 and the tank 21 at ground potential is small, the voltage characteristics are a solid line C when the degree of vacuum is good and a dotted line D when the degree of vacuum is poor, and the voltage change in this example is larger when the degree of vacuum deteriorates. It turns out that. Further, since the distance between the vacuum shield disconnector 26 and the tank 21 is small, the distance between the equipotential lines therebetween becomes close, and the electric field increases especially when the degree of vacuum deteriorates and the potential of the shield 9 increases. Since the electric field and electric field change become larger in this way, the electric field detection sensitivity of the element 37 is improved.

Further, in the above embodiment, the detection section such as the element 39 is installed inside the second case 35, and
is the second case 33 recessed inward of the tank 21
Since the optical fibers 42, 4 are installed inside the
3 does not need to be penetrated tightly into the tank 21, and when replacing the element 39, the second case 35 and cover 45 need only be removed, and there is no need to remove the first case 33, so the airtightness of the tank 21 can be maintained. dripping Furthermore, since the sensing portion such as the element 39 is supported on the tank 21 side via the insulating mold material 44, etc., it is not easily affected by shocks when the vacuum chamber or disconnector 26 is opened and closed, and malfunctions do not occur. Furthermore, since the detection section is sealed by the insulating mold material 44, moisture, dust, etc. do not enter, the life of the element 39 is long, and malfunctions do not occur. Furthermore, since the detection section and the optical fibers 42 and 43 are insulative, the insulating properties of the vacuum shearing device as a whole are not impaired.

Furthermore, the first case 33 and the second case 35
Since there is a gap 36 between them, there is no need for strict dimensional accuracy between the two, and by filling the gap 36 with insulating fluid, corona discharge can be prevented during this time, improving the sensitivity of the detection part. can.
Furthermore, by providing the cover 45 at ground potential, safety for the human body can be maintained, and since the recess 45a of the cover presses the insulating mold material 44, there is no space between the second case 35 and the insulating mold material 44. Peeling is difficult to occur and no corona discharge occurs during this time. Further, since the electric field is concentrated at the tip of the recess 45a, the electric field detection sensitivity of the element 39 is improved.

In addition, when a rubber material is used as the insulating mold material 44, the elasticity is large, so that the detection part and the optical fibers 42, 43 will not be destroyed when cured and shrunk.
Epoxy resin is suitable as the material for each case 33, 35, but if arcing is likely to occur, alumina may be used as the filler, and if arcing is difficult to occur, silica may be used as the filler.

FIG. 8 shows a second embodiment of the present invention, in which a hole 21e is provided in a side plate 21d of a tank 21, and the peripheral part of the hole 21e is made to protrude outward to form a flange portion 21f. It has the same configuration as the one above, but is equipped with a vacuum level monitoring device. However, in this example, the first case 33' and the second case 3
5' and the concave part (corresponding to 45a) of the cover 45' are made longer to shield the sensing part such as the element 39.
It is positioned near the outer periphery of the

In each of the above embodiments, the polarizer 40 and the analyzer 41 are provided in the insulating mold material 44, but the polarizer 40 and the analyzer 41 may be provided on the outside of the cover 45 via an optical fiber. .

As described above, in the present invention, a vacuum breaker is housed in a tank, and a gap in the tank is filled with an insulating fluid. The first case is made of an insulating material that is recessed toward the inside of the tank, and the insulating material is recessed toward the inside of the tank. A second case provided and attached, a light emitting part, a polarizer, and an electro-optic effect element disposed at the outer periphery of the vacuum shield and disconnector in the second case and fixed by molding with an insulating molding material. A vacuum level monitoring device consisting of an analyzer is installed, and the amount of light passing through the analyzer is detected by the element, which detects the electric field on the outer circumferential side of the vacuum shield and disconnector, which changes depending on the vacuum level of the vacuum shield and disconnector. The deterioration of the vacuum level is detected from the change in the vacuum level, and a vacuum level monitoring device that is simple in construction, small in size, and inexpensive can be obtained. Furthermore, since the tank is filled with an insulating fluid having a high dielectric strength, the distance between the vacuum breaker and the tank can be reduced, and the electric field therebetween can be increased.
Further, by making the above-mentioned interval small, the capacitance between them increases, and the change in the electric field around the vacuum chamber and the periphery of the disconnector increases when the degree of vacuum deteriorates. Due to such a large electric field and electric field change, the electric field detection sensitivity of the element is improved, and the vacuum degree monitoring function is also improved. Further, the element has a second part recessed inwardly of the tank.
The second case is sealed and installed in a hole in the tank, and the second case is stored in a first case recessed toward the inside of the tank and is installed on the outside of the first case. Therefore, there is no need to closely penetrate the tank wall to draw out the optical information from the element, and there is no need to remove the first case when replacing the element, so the insulating fluid inside the tank does not leak out.
It becomes easy to install a vacuum level monitoring device. Furthermore, since the element is supported on the tank side rather than on the vacuum shield or disconnector, damage or malfunction due to impact when opening and closing the vacuum shield or disconnector will not occur. Furthermore, since the element is molded and fixed using an insulating molding material, there is no intrusion of moisture or dust, the life is long, and malfunctions are less likely to occur. Further, since the element is made of an insulating material, the provision of the element does not cause problems in terms of insulation, and since the element, polarizer, and analyzer are passive elements, there are few failures, and the reliability of the device is high. Further, the second case is installed in a sealed manner in the hole of the tank and is housed with a gap 36 in the first case which is recessed inward of the tank. It is not necessary to strictly match the dimensions of the space 36, and since the insulating fluid is filled in this space 36, corona discharge is prevented during this time, and the sensitivity of the detection section is improved.

Furthermore, the degree of vacuum can be monitored whether the vacuum chamber or disconnector is open or closed, and the degree of vacuum can be constantly monitored.

[Brief explanation of drawings]

Figures 1A and B and Figure 2 are respectively a longitudinal sectional front view of the vacuum shield breaker in the energized state, an equivalent circuit diagram, and a diagram of the relationship between the degree of vacuum and the voltage and electric field of each part, and Figures 3A and B are respectively Vertical front view and equivalent circuit diagram of the vacuum shield breaker in the shielded state, Figure 4 A, B, C
5 to 7 are respectively a longitudinal sectional front view of a vacuum shear cutting device having a vacuum monitoring device according to a first embodiment of the present invention, a longitudinal sectional front view of the vacuum monitoring device, a bottom view of the vacuum monitoring device, and a bottom view of the vacuum monitoring device. 8 is an explanatory diagram of the operation of the vacuum degree monitoring device according to the first embodiment of the present invention, a voltage distribution diagram between the vacuum shield breaker and the tank, and FIG.
FIG. 2 is a longitudinal sectional front view of a vacuum shear cutting device having a vacuum level monitoring device according to an embodiment of the present invention. 9...Shield, 21...Tank, 21b, 2
1e...hole, 26...vacuum shield, 31...insulating fluid, 33, 33'...first case, 35,
35'... second case, 39... electro-optic effect element, 40... polarizer, 41... analyzer, 42,
43... Optical fiber, 44... Insulating mold material, 48... Light emitting section, 49... Light receiving section.

Claims (1)

[Claims] 1 A vacuum shield is provided with a conductor in which a voltage is applied and current flows in the vacuum section, and a vacuum shield and disconnector having a metal member that is insulated from the conductor and faces across the vacuum space is housed in the tank, and the Sky =
In a vacuum insulation device filled with insulating fluid,
A first case made of an insulating material that is sealed and attached to a hole provided in the tank and is recessed toward the inside of the tank; a second case housed with a gap therebetween and hermetically attached to the outside of the first case; an insulating fluid sealed within the gap between the first case and the second case; and a light emitting section. and a polarizer that linearly polarizes the light from the light emitting part, and a polarizer that linearly polarizes the light from the polarizer, which is placed on the outer periphery of the metal member of the vacuum shield in the second case and fixed to the metal member with an insulating molding material. 1. A vacuum degree monitoring device for a vacuum shearing device, comprising an electro-optic effect element that rotates the plane of polarization of the plane according to the magnitude of an applied electric field, and an analyzer that receives light from the electro-optic effect element.