Current Transformer High-Frequency Bypass Reduces Core Heating
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current transformers for self-powering circuit breakers face issues with high-frequency signal-induced heating and increased energy consumption due to power loss, especially when handling high-frequency signals, which can lead to component breakdown and inefficient energy use.
Innovation Solution
A current transformer design featuring a high-frequency bypass connected in parallel with the first winding, which acts as a low-impedance path for high-frequency signals, reducing the magnetic flux and heating by allowing high-frequency signals to be conducted to the secondary side, and incorporating a short circuit winding to offset magnetic flux, thereby minimizing power loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bypass core is added to limit secondary current, then current limiting effect is achieved, but heating occurs in main core and bypass core due to high-frequency signals
Solution Approach 1:
A high-frequency bypass capacitor is introduced as an intermediary element connected in parallel with the secondary winding. This capacitor provides a low-impedance path for high-frequency signals, allowing them to bypass the bypass core and its associated winding losses, thereby reducing heating while maintaining the current limiting function for fundamental frequencies.
Solution Approach 2:
The solution changes the electrical parameters of the secondary circuit by adding a capacitor that selectively affects different frequency components. The capacitor's reactance decreases with increasing frequency, automatically providing lower impedance for high-frequency signals while maintaining higher impedance for fundamental frequency currents, thus reducing core heating without compromising current limiting.
2Reliability
If bypass core with second winding is used to limit secondary current, then current limiting is achieved, but power loss increases due to field current between windings
Solution Approach 1:
The high-frequency bypass capacitor acts as an intermediary that diverts high-frequency energy away from the lossy magnetic path through the bypass core. By providing an alternative low-impedance route for high-frequency currents, the capacitor reduces the field current circulating between the first and second windings, thereby minimizing power losses while preserving the bypass core's current limiting function.
Solution Approach 2:
The high-frequency signal component is extracted from the main magnetic circuit by the bypass capacitor. This separation removes the harmful high-frequency energy from the core losses, allowing the bypass core to focus on its primary function of limiting secondary current for fundamental frequencies without the additional burden of high-frequency power losses.
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 effectively reduces heating and power loss in the current transformer, maintaining low energy consumption even at high primary current frequencies, protecting components and improving the efficiency of the circuit breaker.
Implementation Method 1
a high-frequency bypass, which is connected in parallel with the first winding, and used to filter a high-frequency signal. The high-frequency bypass provides a low-impedance path for a high-frequency signal in a primary conductor under measurement, such that the bypass core with the second winding presents less obstruction to the main core.
Implementation Method 2
the provision of the high-frequency bypass helps the high-frequency signal to be conducted to the secondary side (i.e. the current transformer) relative to the primary conductor, thereby reducing the field current between the first winding and second winding, and in turn reducing heating.
Data Source
AI summary
A current transformer and a direct current source based on a current transformer are disclosed. In an embodiment, the current transformer includes two output ends; a first winding and a second winding connected in series between the two output ends; a main core; a bypass core, arranged to be magnetically coupled with the main core. The first winding is wound on a part of the main core and a part of the bypass core, and the second winding is wound on apart of the bypass core. In an embodiment, the current transformer also includes a high-frequency bypass, connected in parallel with the first winding, and used to filter a high-frequency signal. The high-frequency bypass provides a low-impedance path for a high-frequency signal in a primary conductor under measurement, such that the bypass core with the second winding presents less obstruction to the main core, thereby reducing heating.