Precision Shunt With Coaxial Sections For High Speed Current Measurement
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Solution Overview
Problem
Current current transformers distort high-frequency signals during short circuit events due to magnetic losses, and shunt sensors are susceptible to external magnetic fields, compromising precision in high-speed electrical current measurements.
Innovation Solution
A precision shunt with coaxial sections of varying resistances, where the internal and outer conductors are connected in series, forming a symmetric bridge configuration that self-compensates for magnetic noise and preserves high-frequency signal integrity, using materials like steel and copper for optimal resistance matching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a current transformer is used for measuring electrical current, then the measurement is adequate for frequencies below megahertz, but magnetic losses in the core significantly distort the signal and degrade precision when frequency components reach the megahertz range
Solution Approach 1:
The shunt is divided into multiple sections, each with outer and inner conductors of different resistance materials (steel and copper). This segmentation allows each section to contribute differently to the overall measurement, with the differential resistance configuration canceling out magnetic field effects while maintaining high-frequency response capability.
Solution Approach 2:
Different sections of the shunt have locally differentiated properties - specifically, alternating sections have outer conductors with higher resistance and inner conductors with lower resistance, and vice versa. This local quality variation creates a symmetric bridge configuration that self-compensates for magnetic field-induced voltage errors at each location.
2Speed
If a shunt sensor with conductor in series is used for measuring electrical current, then the frequency response is improved, but wiring to the sensor becomes sensitive to external magnetic fields which can be very strong during short circuit events
Solution Approach 1:
The shunt employs asymmetric material assignment in alternating sections - steel outer conductors with copper inner conductors in one section, and copper outer conductors with steel inner conductors in the next section. This controlled asymmetry creates differential resistance patterns that generate compensating voltages to cancel magnetic field interference, while the coaxial geometry maintains good frequency response.
Solution Approach 2:
The invention converts the harmful effect of strong magnetic fields during short circuits into a beneficial self-compensation mechanism. The magnetic fields that would normally induce erroneous voltages instead induce proportional voltages in the differential resistance sections that cancel each other out, transforming the interference into a nullifying effect.
3Ease of manufacture
If wiring is used to connect the shunt sensor, then the connection is simple, but the wiring becomes sensitive to external magnetic fields compromising measurement precision
Solution Approach 1:
The measurement function and magnetic field compensation function are merged into a single integrated shunt structure. The same conductor assembly that carries the current to be measured also performs the magnetic field cancellation through its differential resistance configuration, eliminating the need for separate compensation wiring or circuits.
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 solution provides accurate, high-speed measurements of electrical current by neutralizing magnetic field-induced noise and preserving high-frequency components, ensuring precise characterization of electrical faults and events.
Implementation Method 1
The outer conductor and the internal conductor of the first section can be coaxial relative to one another, and the outer conductor and the internal conductor of the second section can be coaxial relative to one another
Implementation Method 2
an internal conductor having a resistance that is lower than the resistance of the outer conductor; a second section abutting the first section and having an outer conductor surrounding an internal conductor having a resistance that is higher than the resistance of the outer conductor
Data Source
AI summary
A shunt for measuring current passing through a conductor. The shunt includes a first section and a second section connected in series with the conductor, and a coaxial cable connected between the first and second sections. An outer conductor of the first section surrounds an internal conductor having a resistance lower than that of the outer conductor of the first section. An outer conductor of the second section surrounds an internal conductor having a resistance higher than that of the internal conductor of the second section. The dimensions of the first and second sections are the same. An internal conductor of the cable is connected between the two sections, and an outer conductor of the cable is connected to the outer conductors of the two sections. The voltage across the outer and inner conductors of the cable is proportional to the current passing through the conductor.