Vertical Zero Flux Current Transformer with SF6 Insulation
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Solution Overview
Problem
Existing zero-flux current transformers require significant space and are costly due to high energy demands and insulation needs when measuring high-voltage currents, with traditional insulation methods posing safety risks and inefficiencies.
Innovation Solution
A vertically aligned zero-flux current transformer design with a core housing connected to ground potential, using SF6 gas for insulation and a support insulator, along with both iron-core and iron-coreless detection windings to measure currents across various frequency ranges, reducing footprint and material costs while ensuring safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a horizontally oriented high-voltage wall bushing is used for electrical isolation, then the required voltage isolation is achieved, but the space requirement and material consumption increase significantly
Solution Approach 1:
The patent transitions from horizontal to vertical orientation of the support insulator, changing the spatial dimension of electrical isolation. The vertically oriented support insulator extends upward from the housing base rather than horizontally, reducing floor space occupation while maintaining the required electrical isolation distance between high-voltage and low-voltage sides.
Solution Approach 2:
The patent inverts the conventional horizontal bushing arrangement by using a vertically oriented support insulator. This inversion allows the zero-flux current transformer to be positioned closer to the conductor while maintaining adequate insulation, thereby reducing the overall footprint and space requirements.
2Reliability
If oil insulation is used for electrical isolation, then the insulation performance is improved, but the fire risk and safety hazards increase
Solution Approach 1:
The patent replaces flammable oil insulation with SF6 gas, creating an inert atmospheric environment within the housing. SF6 gas provides excellent electrical insulation properties while being non-flammable and chemically inert, thereby eliminating the fire risk associated with oil insulation while maintaining high insulation performance.
Solution Approach 2:
The patent eliminates the need for expensive fire protection measures and continuous monitoring systems that would be required for oil-insulated devices. By using SF6 gas, the system achieves comparable or superior insulation performance without the associated safety infrastructure costs and maintenance requirements.
3Reliability
If a horizontally oriented bushing arrangement is used, then the electrical isolation is achieved, but the device complexity and manufacturing cost increase
Solution Approach 1:
The vertically oriented support insulator serves multiple functions simultaneously: it provides electrical isolation between high-voltage and low-voltage sides, supports the mechanical weight of the housing and internal components, and defines the vertical positioning of the zero-flux current transformer. This multi-functionality reduces the need for separate structural elements, simplifying the overall device design.
4Measurement precision
If the zero-flux current transformer is positioned closer to the conductor, then the measurement precision is improved, but the electrical isolation requirements become more difficult to meet
Solution Approach 1:
The patent utilizes the vertical dimension for electrical isolation rather than requiring horizontal distance. By orienting the support insulator vertically, the system can position the housing closer to the conductor horizontally while maintaining adequate insulation distance vertically, thereby improving measurement precision without compromising electrical isolation.
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
The design allows for efficient, cost-effective, and safe measurement of high-voltage currents with reduced space requirements and no risk of oil-related fires, supporting a broader frequency range of current measurements.
Implementation Method 1
the support insulator (12) is surrounded by the housing (8), which is at a high-voltage potential (38). The core housing (20) is electrically insulated from the housing (8) by means of the support insulator (12)
Implementation Method 2
The arrangement is also designed such that the core housing is electrically insulated from the housing by means of SF6 gas. The electrical insulation between the core housing and the housing (and thus the electrical insulation between the high-voltage potential of the current being measured and the ground potential) is advantageously achieved using SF6 gas (sulfur hexafluoride)
Implementation Method 3
The transformer has an electrical detection winding that measures the magnetic flux surrounding the conductor, generated by the flowing current
Implementation Method 4
It also has an electrical compensation winding that reduces the magnetic flux to zero. A control circuit and an amplifier circuit adjust the current flowing through the compensation winding (compensation current) so that the magnetic flux of the conductor is always reduced to zero (the zero-flux condition)
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The invention relates to an arrangement comprising a zero flux current transformer (1) having a compensation winding (310) and a detection coil (316). The compensation winding (310) and said detection coil (316) are arranged in a housing (8) which is supported by a vertically oriented support insulator (12).