Load Tap Changer Condition Analysis via Real-Time Monitoring

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Solution Overview

Problem

Existing methods for evaluating the condition of load tap changers in transformers are inaccurate due to reliance on worst-case scenario testing, leading to unnecessary maintenance or premature replacement, while real-world operating conditions are less stressful, thus requiring a more precise method for condition analysis.

Innovation Solution

A method and device for condition analysis of load tap changers that acquire real-time data considering tap changer-specific parameters, including load current, step voltage, switching direction, temperature, and other operational factors, using sensors and machine learning, to determine characteristic values such as contact erosion and insulation strength, enabling accurate maintenance optimization and early detection of critical conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If service life is determined through tests under worst-case conditions, then reliability is ensured, but maintenance or replacement must occur earlier than necessary

Engineering Contradiction:
ImprovereliabilityVSAvoidservice life
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent changes the parameter basis for service life determination from static worst-case test conditions to dynamic real-time operating parameters. By continuously monitoring actual operating conditions (load current, switching frequency, arc duration) and using these varying parameters to update service life predictions, the system adapts the assessment to reflect actual usage patterns rather than conservative test scenarios.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The load tap changer performs self-diagnosis by continuously monitoring its own operating parameters and calculating its own condition index and remaining service life. The system uses embedded sensors and processing to autonomously assess its health status without requiring external worst-case testing, enabling it to self-determine when maintenance is actually needed based on real accumulated stress.

Inventive Principle:
Principle #25Self-service

2Reliability

If safety margin is maintained based on worst-case test results, then reliable operation is ensured, but utilization is reduced

Engineering Contradiction:
Improvereliable operationVSAvoidutilization
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent transitions from a static safety margin approach (fixed based on worst-case tests) to a dynamic safety margin that continuously adapts to actual operating conditions. The condition index and remaining service life are recalculated in real-time based on monitored parameters, allowing the system to operate closer to actual limits when conditions are favorable while maintaining appropriate margins when stress is high, thereby optimizing utilization without compromising reliability.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system implements continuous feedback by monitoring operating parameters and using this information to update the condition assessment and service life prediction. This closed-loop approach allows the safety margin to be dynamically adjusted based on actual accumulated stress rather than static worst-case assumptions, enabling higher utilization while maintaining reliable operation through real-time awareness of actual condition.

Inventive Principle:
Principle #23Feedback

3Measurement precision

If real-time monitoring of operating parameters is implemented, then accurate condition assessment is achieved, but system complexity increases

Engineering Contradiction:
Improvecondition assessment accuracyVSAvoidmonitoring system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent makes existing components perform multiple functions: the control unit that already manages tap switching also monitors operating parameters and calculates condition assessment. Sensors used for basic operation control are leveraged for condition monitoring as well. This multi-functionality approach achieves accurate real-time condition assessment without adding dedicated complex monitoring hardware for each parameter.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent combines the condition monitoring and assessment functionality with the existing control system rather than implementing it as a separate system. The control unit integrates multiple functions: tap switching control, parameter monitoring, condition index calculation, and service life prediction. This merging reduces overall system complexity by consolidating functions into existing components rather than adding separate dedicated systems.

Inventive Principle:
Principle #5Merging (Combining)

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

Enables optimized maintenance schedules and extended service life of load tap changers by accurately reflecting actual load conditions, preventing critical issues through early detection and improving operational reliability.

Implementation Method 1

When the vacuum interrupter is actuated, arcs regularly occur, which melt or vaporize small amounts of the contact material

Methodology Applied
Scientific EffectArc discharge: Electric Arc

Implementation Method 2

arcs regularly occur, which melt or vaporize small amounts of the contact material and can thus lead to contact erosion or irregularities in the contact surface. Furthermore, the vaporized material can cause the insulating gaps inside the vacuum interrupter to become coated with vapor

Methodology Applied
Scientific EffectArc evaporation: Arc Evaporation

Data Source

PatentEP4457846B1State analysis of an on-load tap changer
Publication Date: 2025.11.19 REINHAUSEN GMBH
  • EP4457846B1 patent drawingFigure 1~2

AI summary

The invention relates to a method for the state analysis of an on-load tap changer (2), wherein the on-load tap changer (2) has at least one vacuum switching tube (3) for switching between winding taps of a transformer (4), the method comprising the following steps: - detecting real-time data with respect to the on-load tap changer (2), - determining parameters specific to the tap changer, - determining at least one characteristic value for determining a state index of the on-load tap changer (2) on the basis of the real-time data and the parameters specific to the tap changer, wherein - the state index encompasses a period of time until a due maintenance and/or a remaining service life and/or a remaining number of switching operations of the on-load tap changer (2).