Transformer Frame Compensation Structure for Window Circulating Current
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Solution Overview
Problem
Transformers experience circulating currents within their iron core windows, leading to additional losses, hot spots, and quality issues, which existing solutions like copper compensation rings, bypass cables, full insulation structures, and special lead designs either incur high costs, are not universally applicable, or pose risks with induced voltages.
Innovation Solution
A compensation structure using silicon steel sheet compensators is placed on the borders of the transformer frame to separate high-voltage and low-voltage iron structures, increasing impedance between the window circuit and external leads, thereby reducing induced currents and preventing circulating current transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a copper compensation ring is provided on the surface of a metal frame to create a shielding effect, then circulating current is reduced, but large losses occur on the copper ring and space is occupied in the iron core
Solution Approach 1:
The patent introduces an intermediary component (insulating structure or compensating winding) between the metal frame and the leads to block the circulating current path. This intermediary prevents the harmful current from flowing through the frame while avoiding the energy losses associated with copper compensation rings.
Solution Approach 2:
The patent replaces the electrical shielding approach (copper ring) with a structural solution (insulating materials or winding arrangement). This substitution eliminates the need for high-conductivity materials and their associated losses, using instead physical separation or magnetic circuit modification.
2Reliability
If bypass cables or short-circuit copper bars are added to short-circuit connection points, then reliability is improved, but the solution cannot be applied to all circulating current nodes
Solution Approach 1:
The patent provides a universal solution that can be applied to all circulating current nodes simultaneously. The insulating structure or compensating winding design creates a comprehensive shielding effect throughout the entire frame structure, rather than requiring individual bypass cables at each connection point.
Solution Approach 2:
The patent segments the circulating current path by introducing insulating structures at strategic locations along the frame borders. This segmentation approach divides the continuous current path into isolated sections, preventing current circulation without requiring complete coverage at every node.
3Object-affected harmful factors
If a full insulation structure is designed to prevent circulating current, then circulating current is reduced, but the solution is only applicable to low induced voltage cases
Solution Approach 1:
The patent modifies the insulation parameters and configuration to handle different voltage levels. By adjusting the insulation material properties, thickness, or the design of compensating windings, the solution remains effective across a range of induced voltages, not just low voltage cases.
Solution Approach 2:
The patent employs composite structures combining different materials with complementary properties. This includes using insulating materials with specific dielectric strength combined with magnetic shielding materials, creating a multi-functional structure that addresses both insulation requirements and magnetic field management across various voltage levels.
4Object-affected harmful factors
If a large-current lead winding with even-numbered layers is designed to avoid equivalent current circuits, then circulating current is reduced, but material costs increase greatly
Solution Approach 1:
The patent extracts the circulating current problem from the winding design itself and addresses it separately through frame border modifications. By placing insulating structures or compensating windings on the frame borders rather than redesigning the entire lead winding structure, the solution avoids the material cost increases associated with even-numbered layer configurations.
Solution Approach 2:
Instead of modifying the winding structure to prevent circulating current (which increases material costs), the patent inverts the approach by modifying the frame structure to block the current path. This reversal transfers the solution from the electrical component to the mechanical structure, reducing material costs.
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 solution effectively reduces circulating currents without additional losses, maintains low costs, and is applicable across various transformer configurations, ensuring safety and efficiency by minimizing induced currents within the transformer frame.
Implementation Method 1
An axial component of the current of a winding and a lead current thereof can be equivalent to a current circuit parallel to an iron core window. A magnetic field of the current circuit will induce a circulating current on a metal structural member of the iron core window.
Implementation Method 2
the at least one compensator made of silicon steel sheets of a magnetic material can separate iron structures between a high-voltage side and a low-voltage side, thereby increasing the impedance between the window circuit of the frame and the current circuit of external leads
Data Source
AI summary
A compensation structure for reducing circulating current in a window of a transformer, the transformer having a winding, a metal frame and leads located at one side of the frame and spaced apart from the frame. The frame has borders and an iron core located inside a window enclosed by the borders. The winding is provided around the iron core, wherein the compensation structure includes at least one compensator on the borders of the frame. The compensator is made of silicon steel sheets of a magnetic material, and the compensator separates at least a part of the borders of the frame from a part of the leads. The compensation structure separates iron structures between a high-voltage side and a low-voltage side, increases the impedance between the window circuit of the frame and the current circuit of external leads, thereby reducing the induced current within the frame and avoiding harmful effects.