Vacuum Loss Detection via Shielded Capacitance Measurement
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Solution Overview
Problem
Existing vacuum breaking devices lack a reliable method to detect loss of vacuum in bulbs without a floating screen, limiting their application to asymmetric bulbs.
Innovation Solution
A device with a casing comprising insulating and conductive materials, featuring capacitors and measurement means to detect changes in vacuum state through current and voltage differential, applicable to both floating and asymmetric bulbs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a capacitor is placed between the floating screen and one of the electrodes to measure vacuum state, then the vacuum detection works for floating screen bulbs, but the device cannot be applied to asymmetric bulbs without a floating screen
Solution Approach 1:
The patent introduces a shield as an intermediary element between the electrode and the external environment. This shield, equipped with measurement strips, serves as a mediator that enables vacuum detection without requiring a floating screen. The shield captures the effect of vacuum changes on capacitance while being electrically isolated, thus making the device applicable to asymmetric bulbs.
Solution Approach 2:
The patent creates a simplified version of the vacuum detection mechanism by replacing the floating screen with a shield that has measurement strips. This 'copy' of the detection function is achieved through capacitance measurement between the shield and electrode, eliminating the need for the complex floating screen structure while maintaining detection capability.
2Measurement precision
If current measurement is used to detect vacuum loss, then the detection is simple, but the signal-to-noise ratio is insufficient for reliable detection
Solution Approach 1:
The patent segments the measurement function into two separate measurement strips (first and second strips) on the shield. By measuring the differential signal between these two strips, the system enhances the signal-to-noise ratio. The segmentation allows for differential measurement that cancels out common-mode noise while preserving the vacuum loss signal.
Solution Approach 2:
The patent changes the measurement parameter from simple current measurement to differential voltage measurement between two strips. This parameter change improves the signal-to-noise ratio by measuring the difference in capacitance effects on two symmetrically positioned strips, thereby enhancing detection reliability.
3Reliability
If a shield with conductive material is added to the casing, then vacuum detection capability is improved, but the device complexity increases
Solution Approach 1:
The shield serves multiple functions simultaneously: it acts as an electromagnetic shield, a support for measurement strips, and a reference element for capacitance measurement. This multi-functionality improves vacuum detection reliability while minimizing the increase in device complexity, as the same structural element performs multiple roles.
Solution Approach 2:
The shield is made of conductive material that can be integrated with the existing casing structure. This composite approach allows the shield to function as both a protective electromagnetic shield and a measurement platform, thereby improving detection reliability without significantly increasing overall device complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables accurate detection of vacuum loss in various bulb types, differentiating between vacuum issues and network faults, with improved signal-to-noise ratios and selective measurement sensitivity.
Implementation Method 1
this so-called first strip forming a capacitor composed of two capacitors in series, respectively a so-called vacuum capacitor, located between the mobile or fixed electrode and the inner face of the first insulating part
Implementation Method 2
If the vacuum state is correct, the dielectric withstand in the bulb is such that almost all of the voltage is between the electrode and the screen
Data Source
Figure 1
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AI summary
The present invention relates to a vacuum loss detection device in a vacuum cutting device comprising a casing (1) having a first part made at least partially of an insulating material such as ceramic, closed at its two opposite ends by two ends (2, 3), said casing (1) housing a fixed electrode (4) and a movable electrode (5). Said casing (1) comprises a second part (26) made of an insulating material and positioned at least partially around the aforementioned first part, this second part constituting an overmolding of the casing and having, on at least a portion of its outer surface, a layer of a conductive material (15) electrically connected to earth, forming a shield.A band (16) called the first of this layer is isolated from the rest of said layer (15), this band called the first being located opposite, on the one hand, the first insulating part (8) and on the other hand, either the fixed electrode (4) or the mobile electrode (5), this band called the first (16) forming a capacitance composed of two capacitances in series, respectively a capacitance called the vacuum (17), located between the mobile electrode (5) or fixed electrode (4) and the inner face of the first insulating part (8), and a capacitance called the solids (18), interposed between the inner face of the aforementioned first insulating part (8) and the band called the first (16), and means for measuring the current flowing in the band called the first (16), a certain value of change in the value of the current reflecting a loss of vacuum inside the vacuum cutting device.