Phasing Voltmeter Stray Capacitive Current Analysis
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High voltage line measurements are hazardous due to the need for frequent contact and the inaccuracies caused by stray capacitive charging currents in existing phasing voltmeters, which fail to analyze and provide valuable information from these currents.
Innovation Solution
A phasing voltmeter with dual input AC voltage measuring devices and a configuration of high and low impedance resistors to create three current paths, allowing for the measurement and analysis of stray capacitive charging currents, thereby determining the source of voltage, leading and lagging phases, phase sequence, and rotation with a single contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a corded phasing voltmeter is used to measure voltage on high voltage lines, then the worker can maintain distance from the line reducing safety risk, but stray capacitive charging currents cause measurement inaccuracies
Solution Approach 1:
The patent measures the stray capacitive charging current that flows through the shield and uses this previously harmful current as a source of information to determine phase sequence, leading/lagging phases, and voltage magnitude relationships. The harmful capacitive current becomes a useful measurement signal that provides additional voltage-related information without requiring additional contact with the high voltage line.
2Adaptability or versatility
If multiple instruments and equipment are used to determine phase sequence and rotation, then comprehensive voltage parameters can be measured, but equipment cost and complexity increase significantly
Solution Approach 1:
The patent enables a single phasing voltmeter to perform multiple measurement functions: voltage magnitude measurement, phase sequence determination, leading/lagging phase identification, and rotation detection. By measuring the stray capacitive charging current and analyzing its characteristics, the device provides comprehensive voltage parameter information that previously required separate specialized instruments, thereby reducing equipment needs and complexity.
3Loss of information
If frequent contact with high voltage lines is made for measurements, then comprehensive voltage parameters can be obtained, but worker safety risk increases
Solution Approach 1:
The patent allows the phasing voltmeter to obtain comprehensive voltage parameter information by measuring the stray capacitive charging current that naturally flows through the shield during normal operation. This self-service approach extracts valuable information from the existing capacitive current without requiring additional worker contact with the high voltage line, thereby reducing safety risks while maintaining measurement capability.
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 solution enables accurate high voltage line measurements with reduced risk to workers by analyzing stray capacitive charging currents, providing additional voltage-related information, and eliminating the need for additional equipment, thus enhancing safety and reducing costs.
Implementation Method 1
The capacitive current is related to the capacitive reactance, Xc, which can range from several thousand ohms up to millions of ohms, depending on the location of the meter and its cable with respect to ground or grounded objects.
Data Source
AI summary
A phasing voltmeter having a dual input AC voltage measuring device in parallel with a series configuration of two high impedance high voltage resistors and two metering resistors. Shielding surrounds and isolates the voltmeter and is connected to the series configuration at a junction between the two metering resistors. The AC voltage measuring device measures the voltage across two voltage lines as well as the exact values of the stray AC capacitive charging currents associated with all high voltage sources. From these previously undesirable stray capacitive charging currents, a math processor in the voltmeter and in contact with two dual input measuring device receives input from between each resistor in the series, determines and displays the actual voltage across the conductors, its origin, the leading phase, lagging phase, phase sequence and phase rotation of the voltages on the AC conductors undergoing testing.