Insulator Evaluation Method for DC Voltage Space Charge
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Solution Overview
Problem
There is a lack of effective methods for diagnosing the state of insulators under direct current (DC) voltage, particularly in power cables and electrical devices, due to the accumulation of space charge and oxidation, which affects insulation performance, and existing methods cannot accurately monitor changes in insulation performance over time.
Innovation Solution
An evaluation method involving the application of a DC voltage to insulators, measuring the integration value of current flowing through them over a prescribed time period, and comparing these values to assess differences in insulation performance, using a current integrator with a capacitor and voltmeter to quantify electric charge and distinguish between charge, space charge, leakage, and partial discharge currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If DC voltage is applied to insulators for power transmission, then power transmission capability is improved, but space charge accumulation and oxidation occur which deteriorate insulation performance
Solution Approach 1:
The patent applies preliminary diagnostic actions by measuring integration values of currents at regular intervals before significant deterioration occurs. This allows early detection of space charge accumulation and oxidation effects, enabling preventive maintenance before insulation performance critically degrades under DC voltage stress
Solution Approach 2:
The patent establishes a feedback mechanism by continuously monitoring integration values of leakage currents and comparing them against reference values from healthy insulators. This feedback system tracks temporal changes in insulation performance and provides real-time information about space charge accumulation and oxidation effects, allowing operators to adjust maintenance schedules and prevent failures
2Measurement precision
If conventional diagnostic methods are used for insulators, then some insulation properties can be assessed, but accurate monitoring of temporal changes in insulation performance under DC voltage is not achieved
Solution Approach 1:
The patent implements continuous monitoring by measuring integration values of currents flowing through insulators at multiple time points during DC voltage application and after voltage removal. This continuous measurement approach captures temporal changes in insulation performance, including space charge accumulation during voltage application and discharge behavior after voltage removal, providing comprehensive diagnostic information that conventional single-point measurements cannot provide
Solution Approach 2:
The patent utilizes changes in electrical parameters (integration values of currents at different time points) to assess insulation performance. By measuring and comparing integration values during voltage application, at steady state, and during discharge phases, the method detects subtle temporal changes in insulation properties caused by space charge accumulation and oxidation, enabling precise monitoring of insulation degradation over time
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 method allows for the comprehensive evaluation of insulation performance by quantifying temporal changes in relative dielectric constant, electric conductivity, and space charge accumulation, enabling the identification of suitable insulator materials and conditions for optimal performance under DC voltage.
Implementation Method 1
Each of integration values is obtained by a current integrator including: a capacitor connected in series to a corresponding one of the first insulator and the second insulator
Implementation Method 2
a voltmeter configured to measure a voltage applied to the capacitor, the current integrator being configured to measure each of the integration values based on a measurement result of the voltmeter
Data Source
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AI summary
An evaluation method for insulation performance includes: a step α of applying a DC voltage to a first insulator on a prescribed applying condition and measuring an integration value of a current flowing through the first insulator from a start of application of the DC voltage until an elapse of a prescribed time period after an end of application of the DC voltage; a step β of applying a DC voltage to the second insulator on an applying condition that is identical to the applying condition in the step α and measuring an integration value of a current flowing through the second insulator from a start of application of the DC voltage until an elapse of a prescribed time period after an end of application of the DC voltage; and a step γ of comparing (i) a first graph showing a relation between an elapsed time period and the integration value that are obtained in the step α and (ii) a second graph showing a relation between an elapsed time period and the integration value that are obtained in the step β, to evaluate a difference between insulation performance of the first insulator and insulation performance of the second insulator due to application of the DC voltage.