Instrument Transformer Correction Unit for Measurement Accuracy

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Solution Overview

Problem

Existing electronic instrument transformers suffer from low accuracy in measuring electrical parameters like voltage and current due to temperature fluctuations, cross-talk effects, and external/internal magnetic and electric fields, leading to significant measurement errors.

Innovation Solution

An apparatus and method that utilize an electronic unit with a correction unit, which applies pre-stored corrective coefficients to calculated electrical parameter values based on detected disturbing factors such as temperature, cross-talk, and external/internal fields, to improve measurement accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If electronic instrument transformers are used to measure electrical parameters, then the device complexity is reduced and response time is improved, but measurement precision deteriorates due to interference signals having a bigger impact on the lower output signals

Engineering Contradiction:
Improvedevice complexityVSAvoidmeasurement precision
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent introduces an intermediary correction unit that processes the output signal of the electronic instrument transformer. This correction unit applies correction coefficients to compensate for measurement errors caused by interference signals, temperature variations, and other disturbing factors. The intermediary acts as a mediator between the electronic transformer and the final measurement reading, improving precision without increasing the complexity of the transformer itself.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent implements a feedback mechanism where the correction unit receives the output signal from the electronic instrument transformer, applies correction based on stored coefficients and detected disturbing factors, and produces a corrected output. This feedback loop continuously compensates for measurement errors, maintaining high precision while keeping the overall system structure relatively simple.

Inventive Principle:
Principle #23Feedback

2Measurement precision

If temperature compensation is applied to correct measurement errors, then measurement precision is improved, but device complexity increases due to additional temperature sensors and correction circuits

Engineering Contradiction:
Improvemeasurement precisionVSAvoiddevice complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The correction unit is designed to perform multiple functions: it compensates for temperature effects, interference signals, and other disturbing factors using a single integrated component. By storing multiple sets of correction coefficients for different disturbing factors and selecting the appropriate coefficients based on detected conditions, the system achieves comprehensive compensation without proportionally increasing device complexity.

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

3Measurement precision

If correction coefficients are pre-stored for various disturbing factors, then measurement precision is enhanced under different conditions, but manufacturing complexity increases due to additional calibration and storage requirements

Engineering Contradiction:
Improvemeasurement precisionVSAvoidease of manufacture
Core Design Contradiction:
Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent applies preliminary action by pre-storing correction coefficients during the manufacturing and calibration phase. These coefficients are determined in advance for various disturbing factors and stored in the correction unit's memory. This preliminary preparation allows the device to operate with high precision under different conditions without requiring complex real-time calibration, thereby improving ease of manufacture and deployment.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP1936391B1Apparatus and method for improving the accuracy of instrument transformers
Publication Date: 2011.02.09 ABB TECHNOLOGY AG
  • EP1936391B1 patent drawingFigure 1~4
  • EP1936391B1 patent drawingFigure 5~7
  • EP1936391B1 patent drawingFigure 8~10

AI summary

Apparatus and method for improving the accuracy of instrument transformers, wherein one or more electrical parameters related to a phase of an electrical conductor are calculated. Signals related to one or more disturbing factors influencing the measurement of the electrical parameters - such as temperature, cross-talk effects- are also calculated. A corrective unit stores a plurality of corrective coefficients corresponding to different values of the calculated disturbing factors. Such coefficients are applied to the calculated values of the electrical parameters so as to improve the accuracy of measurement.