Resonant Test Set Inductance Adjustment
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Solution Overview
Problem
Conventional resonant test sets for diagnostic testing of power cables are heavy, bulky, and expensive to transport, with unstable test voltages due to engine variations, and struggle to achieve resonance with cables of varying lengths and capacitances, especially at power frequencies of 50 or 60 Hz.
Innovation Solution
A hybrid resonant test system with adjustable inductance and output frequency, using an inverter, exciter, and reactor, controlled by a processing device to achieve resonance with electrical cables, allowing for diagnostic testing over a wide range of lengths and capacitances while reducing size and weight, and enabling operation within the power frequency range of 50 to 60 Hz.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional resonant test sets are used for diagnostic testing of power cables, then the testing capability is achieved, but the equipment becomes heavy and bulky requiring large trucks for transportation
Solution Approach 1:
The patent applies dynamics by making the inductance adjustable through a variable inductor that can change its inductance value dynamically. This allows the test set to adapt to different cable capacitances without requiring multiple fixed inductance values, thereby reducing the overall equipment weight while maintaining full testing capability across different cable types and lengths.
Solution Approach 2:
The patent changes the parameter of inductance from fixed to variable, allowing continuous adjustment of the inductance value. This parameter change enables a single lightweight test set to replace multiple heavy fixed-inductance test sets, as the variable inductor can be tuned to match the resonant frequency requirements for cables of varying capacitance and length.
2Device complexity
If conventional resonant test sets with fixed inductance are used, then the equipment structure is simplified, but resonance cannot be achieved with cables of varying lengths and capacitances
Solution Approach 1:
The variable inductor provides dynamic adjustability of inductance, allowing the test set to adapt to different cable capacitances. This dynamic parameter adjustment maintains relatively simple equipment structure while significantly improving adaptability, as the same physical device can be tuned to resonate with cables of any length or capacitance value.
Solution Approach 2:
The variable inductor enables a single test set to perform multiple functions by adjusting its inductance to match different cable characteristics. This universal design replaces the need for multiple specialized test sets with fixed inductances, achieving versatility without proportionally increasing device complexity.
3Ease of operation
If conventional resonant test sets are used, then the equipment can be transported to field locations, but the transportation costs and fuel consumption increase due to requiring large heavy-duty trucks
Solution Approach 1:
The variable inductor reduces equipment weight while maintaining field deployment capability. By allowing dynamic adjustment of inductance, the system eliminates the need for multiple heavy fixed-inductance units, resulting in a single lightweight portable test set that can be transported in smaller vehicles with lower fuel consumption.
Solution Approach 2:
The invention segments the functionality of multiple fixed-inductance test sets into a single variable inductance unit. This segmentation consolidates what would otherwise require multiple heavy pieces of equipment into one lightweight portable system, reducing transportation energy loss while maintaining complete field testing capability.
4Device complexity
If conventional test sets with constant frequency and variable inductance are used, then the design is simplified, but resonance cannot be achieved with cables having large capacitances requiring large air gaps
Solution Approach 1:
The patent changes the operating approach by allowing frequency to vary dynamically rather than remaining constant. This parameter change enables resonance with large-capacitance cables using small air gaps, as the frequency can be adjusted to match the resonant condition without requiring physically large reactor structures. The variable frequency compensates for the limited inductance range of compact reactors.
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
The system achieves stable and efficient diagnostic testing of power cables with reduced size and weight, allowing for transportation in smaller vehicles and lower operating costs, while maintaining resonance across a wide range of cable lengths and capacitances.
Implementation Method 1
If L is the inductance of the reactor, C the capacitance of the cable, and f the frequency of the voltage source, resonance is said to be achieved when 2πfL = 1/(2πfC). Under resonance conditions, the voltage across the test cable becomes a large multiple, Q, of that of the alternating voltage source.
Data Source
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AI summary
Exemplary embodiments of the present disclosure are directed to diagnostic testing of electrical power cables using a resonant test system. The resonant test system can be configured to adjust an inductance to set the inductance of the resonant test system to a test inductance value and to adjust an output frequency of the resonant test system to set the output frequency to a test output frequency. The inductance of the resonant test system can be adjusted by controlling a reactor of the resonant test system and the output frequency of the resonant test system can be controlled by an inverter of the resonant test system. The test inductance value and the test output frequency the test inductance value and the test output frequency can be automatically and dynamically set by a controller of the resonant test system to achieve resonance in series with an electrical power cable under test. One or more diagnostic tests can be performed on the electrical power cable.