Round Wire Electrostatic Shield for Voltage Transformer Field Uniformity

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Solution Overview

Problem

Existing electrostatic shields for medium voltage resin-cast voltage transformers are complex, costly, and difficult to manufacture, often leading to non-uniform electrical field distribution and increased partial discharge, which reduces the transformer's reliability and impulse voltage strength.

Innovation Solution

A shield made from a substantially round copper wire with a diameter at least ten times that of the high voltage winding wire, wound in a concentric configuration to provide a uniform electrical field distribution, minimizing partial discharge and enhancing impulse voltage strength.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If traditional folded edge copper foils are used for electrostatic shields, then the shield can be manufactured with simple materials, but the electrical field distribution becomes non-uniform due to folding difficulties and edge problems

Engineering Contradiction:

Improveshield manufacturing simplicityVSAvoidelectrical field uniformity

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent replaces traditional flat folded copper foils with round copper wire having a substantially round cross-section. This curvature eliminates the edge problems inherent in flat foils and allows the shield to be formed into smooth, uniform concentric circles that distribute the electrical field evenly throughout the transformer insulation system.

Inventive Principle:

Principle #14Spheroidality (Curvature)

Solution Approach 2:

The patent changes the geometric parameters of the shield by specifying that the round copper wire shall have a diameter at least ten times that of the high voltage winding wire. This parameter change ensures that the shield's radius is sufficiently large to create a uniform electrical field while maintaining ease of manufacturing through simple concentric winding.

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If complex interleaved layers of insulating and conducting strips are used for shields, then the electrical field uniformity improves, but the manufacturing complexity and cost increase significantly

Engineering Contradiction:

Improveelectrical field uniformityVSAvoidshield structure complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent extracts and eliminates the complex interleaved layer structure from the shield design. Instead of using multiple alternating layers of insulating and conducting strips, the invention uses a single continuous layer of round copper wire wound in simple concentric circles, dramatically reducing manufacturing complexity while maintaining electrical field uniformity.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent achieves electrical field uniformity through a homogeneous structure of evenly spaced concentric circles formed by the round copper wire. This uniform circular pattern naturally distributes the electrical field evenly throughout the insulation system without requiring complex heterogeneous interleaved structures.

Inventive Principle:

Principle #33Homogeneity

3Ease of manufacture

If folded copper foils are used for shields, then the material cost is low, but the shield edges create field regulation problems and require precise folding that is difficult to achieve

Engineering Contradiction:

Improveshield fabrication easeVSAvoidfield regulation reliability

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent replaces flat folded copper foils with round copper wire having a substantially round cross-section. This curvature eliminates the edge problems inherent in flat foils and allows the shield to be formed into smooth, uniform concentric circles that distribute the electrical field evenly throughout the transformer insulation system.

Inventive Principle:

Principle #14Spheroidality (Curvature)

4Ease of manufacture

If the shield wire diameter is small (comparable to winding wire), then the shield uses less material and is easier to wind, but the electrical field uniformity deteriorates

Engineering Contradiction:

Improveshield winding easeVSAvoidelectrical field distribution uniformity

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

Inventive Principle:

Principle #35Parameter changes

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 a more reliable and cost-effective electrostatic shield that reduces partial discharge, improves electrical field uniformity, and increases the transformer's impulse voltage strength, while being easier to manufacture and less prone to damage.

Implementation Method 1

The shield and the high voltage coil are sized and dimensioned such that an induced voltage in the shield is less then thirty Volts

Methodology Applied

Scientific EffectElectrostatic induction: Electrostatic Induction

Data Source

PatentUS7737814B1Electrostatic shield and voltage transformer

Publication Date: 2010.06.15 DAMNJANOVIC ALEKSANDAR

AI summary

An electrostatic shield and a voltage transformer having a high voltage winding and a low voltage winding. The shield takes the form of a concentric winded coil, made from a round conductive wire having a layer of insulation around it and a radius of at least ten times the radius of the wire used for the high voltage winding. This shield is dimensioned to surround the high voltage winding of the transformer.