Rotating Ring Core Current Transformer for Precision Measurement
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Solution Overview
Problem
Current current transformers (CTs) with removable magnetic cores suffer from low precision due to air gaps, mechanical stress, and limited magnetic conductivity, leading to increased resistance and phase displacement in measuring alternating current, especially at low current values.
Innovation Solution
The design features two ring cores with radial gaps that rotate to minimize air gaps and increase the connecting surface area, allowing for precise alignment and reducing magnetic resistance, while using high relative magnetic inductivity materials and a live electric circuit with negative resistance to compensate for load resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If removable magnetic cores are used to allow circuit continuity, then ease of operation is improved, but measurement precision deteriorates due to air gaps
Solution Approach 1:
The patent transitions from linear connection of core terminals to radial arrangement with rotational movement. The core terminals are arranged radially around a central axis, allowing them to rotate into alignment and form a continuous magnetic path in the radial dimension, eliminating air gaps while maintaining removable functionality.
Solution Approach 2:
The patent introduces rotational movement to dynamically align the core terminals. The cores can rotate around the central axis to bring their terminals into precise alignment, transforming the magnetic circuit from a static disconnected state to a dynamic connected state, eliminating air gaps through motion.
2Reliability
If mechanical stress is applied to connect core terminals, then reliability is improved, but initial magnetic conductivity deteriorates
Solution Approach 1:
The patent employs a radial and rotational geometry where core terminals curve around a central axis. This curved, radial arrangement allows terminals to approach each other along a circular path, enabling connection through rotation rather than linear compression, thereby avoiding mechanical stress that would damage fragile magnetic materials.
Solution Approach 2:
The patent replaces linear mechanical compression with rotational movement to achieve terminal connection. Instead of pushing terminals together along a straight line (which applies compressive stress), the cores rotate to bring terminals into alignment, using tangential forces that preserve the structural integrity and magnetic properties of the materials.
3Measurement precision
If core terminal connection area is increased, then magnetic conductivity is improved, but device complexity increases
Solution Approach 1:
The radial arrangement of core terminals serves multiple functions simultaneously: it increases the effective connection area, enables rotational alignment, and maintains a compact structure. The same radial geometry that expands connection surface also facilitates the rotational mechanism, achieving multiple benefits without proportional increase in 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
This approach significantly increases the secondary coil inductivity, reduces phase displacement, and enhances measurement precision to match that of CTs without air gaps, achieving a phase displacement of 10^-3 degrees, suitable for monitoring electric power and energy.
Implementation Method 1
two ring cores with radial gaps that rotate to minimize air gaps and increase the connecting surface area, allowing for precise alignment and reducing magnetic resistance
Implementation Method 2
secondary coil inductivity, which is due to the active load parameter, first of all, impacts the CT phase displacement
Implementation Method 3
using high relative magnetic inductivity materials and a live electric circuit with negative resistance to compensate for load resistance
Data Source
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AI summary
The invention is intended for measuring an alternating current without interrupting a current-conducting conductor of an electric circuit. The current transformer comprises a primary winding formed by a current-conducting conductor of a circuit, a magnetic circuit comprising at least two concentrically coincident annular cores, and a secondary winding, which surrounds the magnetic circuit over part of the perimeter thereof. In accordance with a first variant, the magnetic circuit cores are arranged in an annular framework, which is designed with the possibility of rotation of at least one of the cores about the common geometrical axis of said cores. The secondary winding is arranged on the annular framework. The magnetic circuit cores and the annular framework are formed with radial gaps which provide for the passage of the current-conducting conductor of the circuit. In the current transformer in accordance with a second variant, one of the annular cores in the form of a hollow ring with the possibility of rotation of at least one of the annular cores arranged in said hollow ring about the common geometrical axis of said annular cores acts as the framework. In order to bring the current transformer into a working position, at least one of the cores is rotated through part of a full revolution about the common geometrical axis of said cores.