JPH0121573B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vacuum monitoring device for a vacuum switch such as a vacuum switch or disconnector.

In general, the performance of vacuum switches such as vacuum switches and disconnectors 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, and has a simple, small, and inexpensive configuration, no problems with insulation, the ability to constantly monitor the degree of vacuum with high reliability, and a vacuum switch that is easy to install. The purpose of this invention is to provide a device for monitoring the degree of vacuum in a vessel.

Embodiments of the present invention will be described below with reference to the drawings.
First, the basic idea of the present invention is shown in FIGS. 1A and B.
This will be explained with reference to FIG. 2 and FIGS. 3A and 3B. Figures 1A and 1B show a vacuum shield breaker and its equivalent circuit in a energized state, where 1 is a fixed electrode, 2 is a movable electrode, 3 is a fixed lead, 4 is a movable lead, and 5 is a movable lead.
is an insulating tube, 6 and 7 are end plates sealed to both ends of the insulating tube 5, the fixed lead 3 is attached to the end plate 6, and the movable lead 4 is sealed to the end plate 7 via a bellows 8. . 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, 12 and 13 are the resistance and capacitance between the fixed electrode 1 and the shield 9, respectively, and 14 and 15 are the movable electrode 2 and the load, respectively. shield 9
16a and 16b are the resistances of the insulating tube 5, and 17 is the capacitance between the shield 9 and the ground.

The interior of the above-mentioned vacuum shield and disconnector is maintained at a high vacuum, and when this degree of vacuum deteriorates, the capacitances 13 and 15 will change as follows: ε ₀ (vacuum dielectric constant) ≒ ε atmosphere (atmospheric dielectric constant ), so the resistance is constant, but the resistance 12, 14
decreases rapidly. 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 _V1 , the voltage between the movable electrode 2 and the shield 9 is _{V2, and the voltage between the shield 9 and the ground is V1.} As V ₃ , 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=3/4V (These values are shown as an example and will vary depending on the structure of the vacuum chamber or disconnector and the degree of vacuum.) Therefore, as shown in FIG. 2, the voltage V ₃ across the shield 9 varies greatly depending on the degree of vacuum, and the electric field E near the shield 9 also varies 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 near the shield 9 also increases. In this way, in a vacuum disconnector, the shield 9
The potential changes greatly depending on the degree of vacuum, and the electric field near the shield 9 also changes greatly. Therefore, by monitoring the electric field on the outside of the shield 9, it is possible to constantly monitor the degree of vacuum in the vacuum shield and the disconnector.
Additionally, the degree of vacuum can also be monitored by monitoring the electric field on the outside of the insulating cylinder 5.

Further, FIG. 4 shows the basic configuration of the vacuum level monitoring device according to the present invention, 20 is a polarizer, 21 is an electric field detection section, and as the electric field detection section 21, a Pockels element or a Kerr element is used. will be explained as a Pockels element. 22 is an analyzer, 23 is a light source,
24 is a light receiving section. To explain its operation, light emitted from the light source 23 is sent to the polarizer 20,
The polarizer 20 linearly polarizes the light in the horizontal or vertical direction. The electric field detection unit 21 is provided, for example, near the outer side of the shield 9 of a vacuum shield breaker, and is applied with an electric field E at that position (the direction of the electric field E is determined by the crystal axis of the Pockels element). Depending on the magnitude of E, the polarization plane angle of the light from the polarizer 20 is changed by θ. The light that has passed through the electric field detection section 21 is applied to an analyzer 22 whose polarization plane has a predetermined relationship with the polarization plane of the polarizer 20, and the light that has passed through the analyzer 22 is sent to a light receiving section that outputs an electric signal according to the amount of light. Added. As shown in FIG. 5, when the degree of vacuum in the vacuum chamber or disconnector is good, the electric field E near the outside of the shield 9 is small, and as the degree of vacuum deteriorates, the electric field E increases. Therefore, the change angle θ of the polarization plane of light in the electric field detection unit 21 is small when the degree of vacuum is good;
When the degree of vacuum becomes poor, θ increases. Therefore, if the polarization plane of the analyzer 22 and the polarization plane of the polarizer 20 are at right angles, if the degree of vacuum becomes poor, the analyzer 22
The amount of light passing through increases, and the output A of the light receiving section 24 increases.
increases as shown by the solid line in FIG. Furthermore, when the polarization planes of the analyzer 22 and the polarizer 20 are parallel, if the degree of vacuum becomes poor, the amount of light passing through the analyzer 22 will decrease, and the output A of the light receiving section 24 will be as shown by the dotted line in FIG. becomes smaller. Therefore, deterioration in the degree of vacuum can be detected when the output of the light receiving section 24 suddenly increases or decreases.

FIG. 6 shows a first embodiment of the present invention, in which numeral 25 denotes a solid insulating member molded around a vacuum shield breaker 26 installed horizontally;
A hole 25 is formed in the part corresponding to the lower outer periphery of the shield 9.
a is provided in the radial direction (vertical direction), and this hole 25a
A roof-shaped electro-optic effect element (Pockels element or Kerr element) 27 with sloped sides is supported as the electric field detection part 21 so that the vacuum shield breaker 26 side is the tapered side, and below it is an electro-optic effect element. Element 2
a polarizer 20 that sends light to the element 7; an analyzer 22 that receives light from the element 27; a light source 2 that sends light to the polarizer 20;
3 and a light receiving section 24 that receives light from the analyzer 22.
are provided as appropriate, and a degree of vacuum quality determination section 28 is electrically connected to the light receiving section 24. In this example, the light source 23
The light is applied to the element 27 via the polarizer 20, and in the element 27, the light is reflected by two inclined surfaces, so the input light and output light become parallel, and the output light passes through the analyzer 22 to the light receiving section. Added to 24. Therefore, when the degree of vacuum of the vacuum chamber breaker 26 deteriorates, the electric field applied to the element 27 changes greatly, and the output of the light receiving section 24 changes greatly, and based on this change, the degree of vacuum quality judgment section 28 detects the deterioration of the degree of vacuum. and output for alarms and displays.

FIG. 7 shows a second embodiment of the present invention. In this example, a laser 29 with small beam spread and good linearity is used as a light source, and the light can be used efficiently and the laser 29 is already in a straight line. If the light is polarized, the polarizer 20 can be omitted.

FIG. 8 shows a third embodiment of the present invention, in which the electric field detection section 21 is formed by a rectangular parallelepiped electro-optic effect element 30 and right-angled prisms 31 and 3 closely attached to both sides thereof.
2, and the light is refracted by right angle prisms 31 and 32 so that the input light and output light to the electric field detection section 21 are parallel.

FIG. 9 shows a fourth embodiment of the present invention, in which the electric field detection section 21 is formed from a rectangular parallelepiped electro-optic effect element 33 and a dielectric reflective film 34 that is in close contact with the vacuum shield and the breaker 26 side. The dielectric reflective film 34 reflects input light.

FIGS. 10 and 11 show fifth and sixth embodiments of the invention, respectively, in which the holes 25a
A polarizer 20 and an analyzer 22 are placed in close contact with the light input and output sides of the elements 27 and 33 installed in the interior to eliminate distortion of the plane of polarization in the optical transmission system between them, and also to between and analyzer 22
The optical fiber 3 transmits light between the
5 and 36, it is possible to reduce optical loss and use a light emitting diode, which has low optical power but is inexpensive and highly reliable, as a light source. Note that since the optical fibers 35 and 36 are used only for transmitting optical power, they may be multi-mode optical fibers.

In addition, the electro-optic effect elements 27, 30, and 33 are made of quartz crystal (relative permittivity: 4,
3) is better, but from the viewpoint of sensitivity, it is better to use a material with a high dielectric constant, such as ADP or KDP (relative dielectric constant 40 to 50), which equivalently improves sensitivity due to the electric field concentration effect. However, if a material with an extremely high dielectric constant is used, dielectric breakdown will occur.

In the first to sixth embodiments described above, the vacuum shield breaker 2
Since the hole 25a is provided in the solid insulating member 25 molded with 6 and the electric field detection section 21 is installed in the hole 25a, there is no need to provide any special support means for the electric field detection section 21. Moreover, the electric field detection part 2 is inserted into the hole 25a in this way.
1 was made possible because the electric field detection section 21 reflected the light toward the input direction, and because of this reflective structure, the installation of element 2 was made possible.
The optical path lengths at 7, 30, and 33 become longer, and the angle of change θ of the plane of polarization due to the electric field becomes larger (the angle of change θ changes in accordance with the electric field E and the optical path length L), and the sensitivity of electric field detection is improved. Become.

As described above, the vacuum level monitoring device according to the present invention includes a light source, a polarizer that linearly polarizes the light from the light source, and an electric field sensor that changes the polarization plane angle of the light from the polarizer according to the magnitude of the applied electric field. and an analyzer which has a polarization plane in a predetermined relationship with the polarization plane of the polarizer and which receives light from the electric field detection section. The vacuum switch is supported in a hole formed from the outside at a position on the outer periphery of the vacuum switch in a solid insulating member molded around the vacuum switch at a position where the pressure changes. For this reason,
When the degree of vacuum in a vacuum switch deteriorates, the electric field outside the switch changes, so the polarization plane angle of light in the electric field detection section changes, and the amount of light passing through the analyzer changes. Therefore, deterioration in the degree of vacuum can be detected from changes in the amount of passing light regardless of whether the vacuum switch is opened or closed, and the degree of vacuum can be constantly monitored. In addition, the vacuum level monitoring device has the above-mentioned configuration, so the configuration is simple, and the light source, polarizer, analyzer, and electric field detection unit are all small and inexpensive, so the vacuum level monitoring device is also small. It will be cheap. Furthermore, since the polarizer, analyzer, and electric field detection section are all made of insulating materials, there is no problem in terms of insulation even if these members are provided around the vacuum switch. Furthermore, since at least the electric field detection section is supported within the hole of the solid insulating member molded around the vacuum switch, no special supporting means is required, and the electric field detection sensitivity is improved because it is close to the vacuum switch. Furthermore, since a light reflecting surface is provided on the vacuum switch side of the electric field detection section, the light from the polarizer travels back and forth within the electric field detection section, increasing the optical path length and improving electric field detection sensitivity.

[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 Figures 4 and 5 are a longitudinal sectional front view and an equivalent circuit diagram of the vacuum shield and breaker in the shielded state, respectively, and a basic configuration diagram of the vacuum degree monitoring device according to the present invention, and the relationship between the degree of vacuum, the electric field, and the output of the light receiving section. Relationship diagram, 6th ~
FIG. 11 is a configuration diagram of a vacuum degree monitoring device according to the first to sixth embodiments of the present invention. 20...Polarizer, 21...Electric field detection section, 22...
...Analyzer, 23...Light source, 24...Light receiving section, 25
. . . Solid insulating member, 25a . . . Hole, 26 . . . Vacuum shield breaker, 27, 30, 33 .

Claims (1)

[Claims] 1 In a vacuum switch whose periphery is molded with a solid insulating material, a light source, a polarizer that linearly polarizes the light from the light source, and an electric field detection unit that changes the polarization plane angle of the light from the polarizer according to the magnitude of the applied electric field. and an analyzer that has a polarization plane in a predetermined relationship with the polarization plane of the polarizer and receives light from the electric field detection section, and at least the electric field detection section is connected to the solid insulating member on the outer periphery of the vacuum switch. 1. A degree of vacuum monitoring device for a vacuum switch, characterized in that the electric field detection section has a light reflecting surface on the side of the vacuum switch.