VLF Test Generator Parallel Discharge Resistor
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Solution Overview
Problem
Existing VLF test generators for high voltage insulation testing of capacitive loads, such as power cables, are complex, costly, and prone to high power loss and cooling requirements, making them unsuitable for mobile and on-site use.
Innovation Solution
A VLF test generator design that incorporates a discharging resistor connected in parallel to the demodulator, eliminating the need for a separate switch and utilizing the interference between two oscillators to generate low-frequency modulation, resulting in reduced component count, power loss, and cooling needs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a permanent load-parallel discharging resistor is used, then the capacitive load can be discharged, but power loss increases
Solution Approach 1:
The patent applies the dynamics principle by making the discharging resistor switchable rather than permanent. The resistor is connected in parallel to the demodulator and can be dynamically activated or deactivated based on operational requirements. This allows the system to have discharge capability when needed while minimizing power loss during normal operation, resolving the contradiction between reliability and energy loss.
2Loss of energy
If a switchable load-parallel discharging resistor is used, then power loss is reduced, but additional switching electronics are required
Solution Approach 1:
The patent merges the discharging resistor functionality with the existing demodulator circuit by connecting the resistor in parallel to the demodulator. This integration allows the system to share common circuit elements and control mechanisms, reducing the need for separate switching electronics while still achieving dynamic discharge capability. The merging principle resolves the contradiction between reducing power loss and avoiding increased device complexity.
3Power
If conventional VLF test generator circuits are used, then high voltage can be generated, but the device becomes complex and costly
Solution Approach 1:
The patent applies universality by designing a circuit where the discharging resistor serves multiple functions: it provides discharge capability for the capacitive load, integrates with the demodulator circuit, and can be dynamically controlled. This multi-functional design reduces the need for separate dedicated components, thereby reducing overall device complexity while maintaining high voltage generation 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
The solution achieves significant cost, weight, and cooling savings while generating high amplitude, low-frequency voltages with minimal components, making it suitable for mobile on-site testing with reduced power loss and enhanced robustness.
Implementation Method 1
generating an interference product in a resonant circuit
Implementation Method 2
resonant circuit which is tuned to the oscillator frequencies
Implementation Method 3
amplitude-modulate a mains frequency high voltage
Implementation Method 4
a discharging resistor for the capacitive load which leads back to the stated output is connected in parallel to the demodulator
Data Source
AI summary
Disclosed is a very low frequency test generator for generating a high voltage having a low frequency in order to test the insulation of capacitive loads, in particular power cables. Said VLF test generator comprises an oscillator part which generates a high voltage that has a high frequency and is modulated with a lower frequency at an output, and a demodulator which is connected to the oscillator part, demodulates the high voltage, and recovers the low frequency therefrom. A discharge resistor for the capacitive load is connected in parallel to the demodulator, said discharge resistor conducting back to the aforementioned output.