Hinged Split-Core Current Transformer for Branch Circuit Monitoring
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Solution Overview
Problem
Existing smart meter systems for energy monitoring and distribution face limitations in accurately measuring individual branch circuit energy consumption, as they often require disconnecting power or using bulky and unreliable current transformers that can cause safety hazards and signal interference.
Innovation Solution
A current transformer design with a hinged, split-core configuration and a latch mechanism that allows for safe, one-handed operation and secure closure, featuring a sensing gap for non-contact current extraction and a Hall-effect sensor for precise measurement, enabling flexible and accurate monitoring of branch circuit currents without disconnecting power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a traditional current transformer is used to measure branch circuit current, then current measurement is achieved, but the device becomes bulky and heavy causing mounting difficulties and potential loosening
Solution Approach 1:
The current transformer core is divided into two separate halves that can be independently positioned and secured. This segmentation allows the transformer to be installed without removing the circuit breaker, eliminating the need for heavy single-piece transformers while maintaining measurement accuracy through proper magnetic circuit configuration.
Solution Approach 2:
The current transformer is designed to fit within the existing circuit breaker enclosure space. The toroidal core with its two halves nests around the bus bar, and the entire assembly fits within the circuit breaker box, eliminating the need for external mounting of bulky transformers.
2Ease of operation
If a hinged split core sensing transformer is used to easily affix to power cable, then installation ease is improved, but calibration is lost over time resulting in measurement inaccuracy
Solution Approach 1:
The position of the two core halves is predetermined and designed to automatically align with the bus bar when installed. The circuit board is pre-positioned to ensure correct spacing and alignment, eliminating the need for field calibration while maintaining ease of installation.
Solution Approach 2:
The transformer design includes self-aligning features where the core halves naturally position themselves relative to the bus bar during installation. The mechanical structure and circuit board mounting ensure automatic calibration without requiring external adjustment or calibration procedures.
3Object-affected harmful factors
If power is disconnected to install current sensor at circuit breaker box, then safe sensor installation is achieved, but work time is lost due to power disruption
Solution Approach 1:
The circuit breaker is divided into removable components (the breaker itself can be pulled out while the transformer remains installed on the bus bar). This allows the transformer to be installed once and retained, while individual breakers can be safely removed for installation without disrupting power to the entire panel.
Solution Approach 2:
The current transformer is pre-installed on the bus bar before any circuit breakers are removed. This preliminary installation ensures the sensor is in place and calibrated before any electrical work begins, eliminating the need to disconnect power for the installation process itself.
4Measurement precision
If multiple signal leads are used in current transformer, then electrical connection is achieved, but interference and crosstalk occur resulting in poor signal quality
Solution Approach 1:
The electrical connection between the transformer windings and the circuit board is achieved through direct mechanical contact via spring-loaded contacts or conductive plates, eliminating the need for separate signal leads. This substitution reduces interference and crosstalk while maintaining electrical connectivity.
Solution Approach 2:
The signal leads are integrated directly into the circuit board traces rather than being separate external connections. The electrical pathways are merged with the board's existing conductive structures, reducing the number of discrete leads and minimizing interference while maintaining signal integrity.
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 safe, accurate, and flexible monitoring of branch circuit currents, reducing the risk of safety hazards and signal interference, while allowing for easy installation and operation, enhancing the reliability of energy monitoring systems.
Implementation Method 1
A related art sensing transformer that produces an output representative of the electrical current carried by the conductor
Data Source
AI summary
A current transformer having a body having an upper half and a lower half hingedly connected to the upper half, a pair of ferrite cores located within one of the upper half and the lower half of the body, the pair of ferrite cores defining a gap formed between each ferrite core of the pair of ferrite cores, and a sensor located within the gap formed between each ferrite core of the pair of ferrite cores.