Transformer Winding Shield for Capacitance Distribution
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Solution Overview
Problem
Existing transformer windings with cooling channels experience non-uniform capacitance distribution during surge voltage loading, leading to uneven voltage loading of conductors, particularly in dry-type transformers where cooling channels are thicker, affecting the distribution of stray capacitance.
Innovation Solution
Incorporating a flat electrical shield within the cooling channel along the radial circumference, extending over the entire axial length, to influence and homogenize the electrical capacitance distribution in series-connected transformer windings, while maintaining or enhancing the cooling effect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If cooling channels are introduced to improve heat dissipation, then cooling effect is improved, but capacitance distribution becomes non-uniform
Solution Approach 1:
A flat electrical shield is introduced as an intermediary element within the cooling channel. This shield has a specific electrical potential that differs from both the inner and outer winding modules, acting as a mediator to redistribute the electric field and capacitance values. The shield's potential is typically between the potentials of the two winding modules, creating a gradient that promotes more uniform voltage distribution across all turns during surge conditions.
Solution Approach 2:
The electrical shield changes the electrical parameters (capacitance and voltage distribution) within the cooling channel region. By introducing this intermediate electrical structure, the capacitance values of turns adjacent to the cooling channel are increased, and the voltage distribution during surge loading is modified to be more uniform across the winding modules.
2Temperature
If cooling channel thickness is increased to improve cooling in dry-type transformers, then cooling effect is improved, but capacitance distribution non-uniformity worsens
Solution Approach 1:
The flat electrical shield serves as a mediator that becomes increasingly important as the cooling channel thickness increases. In dry-type transformers with thicker cooling channels (few centimeters), the shield's presence ensures that even turns far from the winding modules experience more uniform voltage distribution during surges, compensating for the larger void space that would otherwise create significant capacitance non-uniformity.
3Loss of energy
If cooling channels are introduced to dissipate heat, then heat dissipation is improved, but voltage distribution during surge loading becomes non-uniform
Solution Approach 1:
The flat electrical shield mediates the electric field distribution in the cooling channel region. During surge voltage loading, the shield's intermediate potential creates a more gradual voltage gradient across the winding modules, preventing the concentration of voltage stress that would occur in the absence of the shield, thus protecting the insulation system.
Solution Approach 2:
The shield modifies the electrical parameters (capacitance and voltage distribution) in the cooling channel region, changing the way surge voltages are distributed across the winding. This parameter change ensures that the high-frequency fundamental component of surge pulses distributes voltage more uniformly, reducing peak stress on individual turns and their insulation.
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 electrical shield replicates the capacitive properties of turns without cooling channels, ensuring more uniform voltage distribution during surge voltage loading and steady-state operation, and improves the cooling effect by maintaining airflow and heat exchange.
Implementation Method 1
the electrical capacitance distribution in the transformer winding connected electrically in series is influenced
Implementation Method 2
improves the cooling effect by maintaining airflow and heat exchange
Data Source
AI summary
A transformer winding, having at least two multi-layered winding modules, which are connected electrically in series, extend about a common winding axis, and are nested one inside the other hollow-cylindrically, at least one cooling channel, which is arranged along the common winding axis hollow-cylindrically between the winding modules, and a flat electrical shield is provided within the at least one cooling channel at least sectionally along the radial circumference thereof, wherein the electrical shield extends over approximately the entire axial length and through which electrical shield the electrical capacitance distribution in the transformer winding connected electrically in series is influenced.