Transformer Insulation Moisture Correction via Oil Conductivity

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing methods for determining the moisture content in transformer insulation are inaccurate due to the influence of conductive aging products, leading to overestimation and unnecessary maintenance measures.

Innovation Solution

A method that measures dielectric properties, derives preliminary moisture content, and corrects it using conductivity to account for the effects of conductive aging products, employing a correction formula based on laboratory measurements with differently conductive liquids.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If dielectric properties are measured to determine moisture content, then moisture content can be determined, but the measurement is inaccurate due to interference from conductive aging products

Engineering Contradiction:

Improvemoisture content determination accuracyVSAvoidinterference from conductive aging products

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The measurement process is segmented into two distinct parts: first measuring the total conductivity (which includes both moisture and aging product contributions), then separately measuring the oil conductivity to quantify the aging product portion. By segmenting the conductivity measurement into these two components, the method can isolate and subtract the aging product interference from the total measurement, thereby accurately determining the moisture content contribution alone.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The oil conductivity measurement serves as an intermediary step that indirectly quantifies the aging product content in the solid insulation. By measuring the conductivity of the oil (which contains dissolved aging products), the method creates an intermediary metric that can be used to calculate and compensate for the aging product contribution to the solid insulation's dielectric properties, enabling accurate moisture determination despite the presence of aging products.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If conventional dielectric measurement methods are used, then moisture content can be obtained, but unnecessary maintenance measures are triggered due to overestimation

Engineering Contradiction:

Improvetransformer operational availabilityVSAvoidmoisture content accuracy

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The method implements a feedback mechanism where the measured oil conductivity is used to calculate the aging product contribution, which then feeds back into the moisture content calculation to correct the initial overestimation. This feedback loop allows the system to self-correct the measurement error caused by aging products, providing accurate moisture content values that prevent false alarms and unnecessary maintenance interventions.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The invention replaces the conventional direct moisture measurement approach (which mechanically assumes all conductivity comes from moisture) with an indirect calculation method that uses electrical conductivity measurements of both the total insulation and the oil separately. This substitution of measurement methodology allows for mathematical separation of the conductivity sources, replacing the flawed direct measurement with a corrected indirect calculation that accounts for aging product interference.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 approach provides a precise determination of moisture content, reducing unnecessary maintenance and downtime by accurately compensating for the effects of aging products.

Implementation Method 1

determining or measuring one or more dielectric properties of the insulation

Methodology Applied

Scientific EffectDielectric measurement: Dielectric Permittivity

Implementation Method 2

correcting the preliminary moisture content using conductivity to thereby determine the moisture content of the insulation

Methodology Applied

Scientific EffectElectrical conductivity: Conduction (electrical)

Data Source

PatentEP2026062B1Method and device for determining the humidity content in the insulator of a transformer

Publication Date: 2014.12.17 OMICRON ELECTRONICS GMBH

Figure 1
Figure 2
Figure 3

AI summary

A method and apparatus (20) for determining the moisture content of the insulation (12, 14) of a transformer (16) is described, wherein the insulation (12, 14) comprises a liquid (12). The method comprises the following steps: - measuring (1) at least one dielectric property (CTr(f)) of the insulation (12, 14), - deriving (8) an uncorrected moisture content of the insulation (12, 14) and a conductivity (σOil) of a liquid (12) contained in the insulation (12, 14) from a model (Cm(f)) of the insulation (12, 14), which is selected depending on the measured dielectric property of the insulation (12, 14), and - correcting (9) the moisture content of the insulation (12, 14) using the conductivity (σOil).