CVT Voltage Divider Dissipation Factor Measurement Without Disassembly

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Solution Overview

Problem

There is a need to measure the dissipation factor of capacitor voltage dividers in capacitor voltage transformers without disassembling them, as they operate in high voltage substations that are not equipped with cleanrooms, which could introduce contamination and humidity.

Innovation Solution

A method involving grounded and ungrounded specimen tests to measure currents through the capacitors, coupled with a current sensor, and calculate the dissipation factor using phasor values and capacitance ratios, without disassembling the transformer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the CVT is disassembled to measure CVD dissipation factor, then the measurement can be performed, but contamination and humidity enter the IVT tank

Engineering Contradiction:

Improvedissipation factor measurementVSAvoidcontamination and humidity

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

A test device is introduced as an intermediary between the measurement system and the CVD. This device connects to external terminals of the CVT and performs measurements without requiring disassembly, thereby preventing contamination and humidity from entering the IVT tank while still enabling dissipation factor measurement

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The measurement process is segmented into two distinct modes: GST mode where the low voltage terminal is grounded, and UST mode where the low voltage terminal is ungrounded. By segmenting the measurement into these separate modes with different grounding configurations, the system can calculate the CVD dissipation factor without disassembling the CVT

Inventive Principle:

Principle #1Segmentation

2Ease of manufacture

If the CVD dissipation factor is measured during manufacturing, then the measurement is easy to perform, but it cannot evaluate insulation condition under operation

Engineering Contradiction:

Improvemeasurement easeVSAvoidinsulation condition evaluation

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The measurement system is designed to be dynamically adaptable to both manufacturing and operational environments. By using switchable grounding configurations (GST and UST modes) that can be implemented through external connections, the system maintains measurement capability whether the CVT is newly manufactured or in service, enabling ongoing reliability assessment

Inventive Principle:

Principle #15Dynamics

3Duration of action of stationary object

If a faulty CVT is calibrated with extra error compensation, then it can operate further, but the dissipation factor must be small enough

Engineering Contradiction:

Improveoperational lifeVSAvoiddissipation factor threshold

Core Design Contradiction:

Duration of action of stationary objectVSMeasurement precision

Solution Approach 1:

The system provides feedback on the CVD dissipation factor through separate GST and UST mode measurements. This feedback mechanism allows operators to assess whether the dissipation factor is below the threshold required for calibration and extended operation, or if replacement is necessary, thereby informing decisions about continuing operational life

Inventive Principle:

Principle #23Feedback

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 accurate measurement of the dissipation factor of capacitor voltage dividers in situ, allowing for evaluation of insulation condition and fault detection without disrupting the transformer operation.

Implementation Method 1

measuring a grounded specimen test (GST) mode current that may pass through a first capacitor of the CVD by coupling the current sensor in series with the first capacitor

Methodology Applied

Scientific EffectElectrical Conduction: Conduction (electrical)

Implementation Method 2

CVTs utilize a capacitor voltage dividers (CVDs) connected between phase and ground nodes to decrease voltage level

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 3

CVTs exploit compensating reactors (CRs) to reduce CVT ratio errors, and particularly CVT phase displacement

Methodology Applied

Scientific EffectElectromagnetic Induction: Electromagnetic Induction

Data Source

PatentUS12535506B2Measuring dissipation factor of voltage divider of capacitor voltage transformers

Publication Date: 2026.01.27 ELECTRONIC SAZAN FAN ARIA CO

AI summary

A method for measuring a dissipation factor of a voltage divider of a capacitor voltage transformer (CVT). The CVT includes a capacitor voltage divider (CVD), an intermediate voltage transformer (IVT), and a compensating reactor (CR). The CR is connected between the CVD and the IVT. The method includes measuring a grounded specimen test (GST) mode current that passes through a first capacitor of the CVD by coupling the current sensor in series with the first capacitor, measuring an ungrounded specimen test (UST) mode current that passes through a second capacitor of the CVD by coupling the current sensor in series with the second capacitor, and obtaining a dissipation factor of the CVD based on the GST mode current and the UST mode current.