JPS6148856B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vacuum degree monitoring device for vacuum electrical equipment having a vacuum section to which a voltage is applied.

In general, the performance of vacuum electrical equipment such as vacuum chambers 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, has a simple, small, and inexpensive configuration, and has no problems with insulation, and can constantly monitor the vacuum level with high reliability for vacuum level monitoring of vacuum electrical equipment. The purpose is to provide equipment.

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 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.
will be sealed. 9 is a shield attached to the middle of the insulating cylinder 5. In addition, 10 and 11 are the power supply and load of the circuit in which the vacuum circuit breaker is installed, respectively, and 1
2 and 13 are the resistance and capacitance between the fixed electrode 1 and the shield 9, respectively; 14 and 15 are the resistance and capacitance between the movable electrode 2 and the shield 9, respectively; 16a and 1
6b is the resistance of the insulating tube 5, and 17 is the capacitance between the shield 9 and the ground.

In the vacuum chamber disconnector described above, the interior of the vacuum container formed by the insulating cylinder 5 and the end plates 6 and 7 is maintained at a high vacuum, and even if this degree of vacuum deteriorates, the capacitance will increase. The resistances 13 and 15 hardly change and remain constant, but the resistances 12 and 14 suddenly decrease.
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 ,
Assuming that the voltage between shield 9 and the ground is V ₃ , V ₁ = V ₂ =
V/2, V ₃ = V-V ₁ = V/2, but if the degree of vacuum decreases, V ₁ = V ₂ = V/4, V ₃ = V-
V/4 = 3/4・V (These values are shown as an example and may vary depending on the structure of the disconnector and the degree of vacuum.) Therefore, as shown in Figure 2. The voltage V ₃ of 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, as the degree of vacuum decreases, 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.
In addition, if there is a part other than the shield 9 where the electric field changes depending on the degree of vacuum, the degree of vacuum can be monitored by monitoring the electric field in that part.
The same applies to vacuum electrical equipment other than vacuum shields and disconnectors.

FIG. 4 shows an embodiment of the vacuum level monitoring device according to the present invention, in which 20, 21, 22 are a polarizer, a Kerr element, and an analyzer provided near the outside of the shield 9, and 23 is an optical fiber 24. 25 is a photoelectric conversion unit that receives light from the analyzer 22 via an optical fiber 26 and outputs an electrical signal according to the amount of this light; 27 is a photoelectric conversion unit The degree of vacuum determination section 27 receives the output from the section 25 and determines whether the degree of vacuum is good or bad, and the degree of vacuum judgment section 27 outputs an output for alarm or display depending on whether the degree of vacuum is good or bad.

The operation of the vacuum level monitoring device described above will be explained with reference to FIG. Linearly polarized. 21 is a Kerr element to which an electric field E near the outside of the shield 9 is applied horizontally or vertically (the direction of the electric field E is determined by the crystal axis of the Kerr element).
The Kerr element 21 changes the polarization plane angle of the light from the polarizer 20 by θ in accordance with the magnitude of the electric field E. Since the polarization plane angle change θ is θ∝E ² for the Kerr element compared to θ∝E for the Pockels element, the detection sensitivity for changes in the electric field is greatly improved. Next, the light from the Kerr element 21 is applied to an analyzer 22 whose polarization plane is perpendicular or parallel to the polarization plane of the polarizer 20, and the light that has passed through the analyzer 22 is an electrical signal corresponding to the amount of light. It is added to the photoelectric conversion section 25 which outputs. As shown in FIG. 6, when the degree of vacuum in the vacuum chamber or disconnector is good, the electric field E is small, and when the degree of vacuum is poor or deteriorated, the electric field E increases. Therefore, the change angle θ of the polarization plane of light in the Kerr element 21 is small when the degree of vacuum is good, and becomes large when the degree of vacuum is poor.
Therefore, when the polarization plane of the detector 22 and the polarization plane of the polarizer 20 are perpendicular to each other, if the degree of vacuum becomes poor, the amount of light passing through the analyzer 22 will increase, and the output A of the photoelectric converter 25 will be It becomes as shown by the solid line in FIG. Further, when the polarization plane of the analyzer 22 and the polarization plane of the polarizer 20 are parallel, when the degree of vacuum becomes poor, the amount of light passing through the analyzer 22 becomes small, and the output A of the photoelectric converter 25 becomes The result is as shown by the dotted line in Figure 6. Therefore, the output A is transmitted through the optical fiber 26.
The vacuum level determining unit 27 that receives the signal detects the deterioration of the vacuum level when the output A suddenly increases or decreases, and outputs an output for an alarm or display. In the above embodiment, deterioration in the degree of vacuum is detected by detecting changes in the electric field near the outer periphery of the shield 9 of the vacuum shield/breaker, but it is also possible to detect changes in the electric field in other parts of the vacuum shield/breaker. You can also do it. Furthermore, the vacuum level monitoring device of the present invention can be applied to vacuum level monitoring of other vacuum electrical equipment, such as disconnectors and switches using vacuum shields and disconnectors, vacuum tubes, vacuum gaps, and X-ray tubes. .

As described above, in the present invention, a polarizer, a Kerr element, and an analyzer are provided in a vacuum electrical device having a vacuum section to which a voltage is applied, in which the electric field changes depending on the degree of vacuum outside the vacuum section. The amount of light passing through the analyzer, which changes in proportion to the square of the electric field due to changes in the electric field, is detected by a photoelectric converter to detect deterioration of the vacuum level.The configuration of the vacuum level monitoring device is simple, small, and inexpensive. Become. In addition, the polarizers, Kerr elements, and analyzers in the high-pressure parts around vacuum electrical equipment are not all metal members, and the connection to the photoelectric converter can also be made through non-metallic materials such as optical fibers. There will be no problem with the insulation between the parts and the ground. Furthermore, the polarizer, Kerr element, and analyzer are all passive elements, so there is no fear of failure and high reliability. In addition, since the degree of vacuum is detected using light, it has excellent noise resistance, and the degree of vacuum can be monitored whether the vacuum electrical equipment is open or closed, so that constant monitoring can be performed.

[Brief explanation of the drawing]

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 A vertical sectional front view and an equivalent circuit diagram of the vacuum shield disconnector in the shielded state, and Figures 4 to 6 are a front view, an operation explanatory diagram, and a vacuum level, electric field, and photoelectric conversion of the vacuum level monitoring device according to the present invention, respectively. Relationship diagram with departmental output. 9 is a shield, 20 is a polarizer, 21 is a Kerr element, 22 is an analyzer, 23 is a light source, 24 and 26 are optical fibers, 25 is a photoelectric conversion section, and 27 is a degree of vacuum determination section.

Claims (1)

[Claims] 1 In vacuum electrical equipment that has a vacuum section to which a voltage is applied, a polarizer that linearly polarizes the light from the light source and a polarizer that linearly polarizes the light from the polarizer are installed in the part outside the vacuum section where the electric field changes depending on the degree of vacuum. A Kerr element that changes a polarization plane angle according to the magnitude of the electric field, and an analyzer that has a polarization plane that has a predetermined relationship with the polarization plane of the polarizer and receives light from the Kerr element, and the analyzer 1. A vacuum level monitoring device for vacuum electrical equipment, characterized in that it includes a photoelectric conversion section that outputs an electrical signal according to the amount of light emitted from the vacuum electrical equipment.