Partial Discharge Detection Using Dual UHF Sensors
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Solution Overview
Problem
Existing methods for detecting partial discharges in live electrical apparatuses are unreliable due to external noise interference and inability to differentiate between internal and external discharges, especially during on-site testing, and are often costly and limited in detection capabilities.
Innovation Solution
A dual UHF measurement system with sensors placed both inside and outside the electrical equipment tank, combined with an acquisition and computation system to determine the signal-to-noise ratios and compare them to differentiate between internal and external discharges based on amplitude and timing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single UHF sensor is placed inside the electrical equipment tank, then internal partial discharges can be detected, but external discharges of very high intensity can also be detected causing false positives
Solution Approach 1:
The detection system is segmented into two separate measurement systems: one sensor placed inside the electrical equipment tank for detecting internal discharges, and another sensor placed outside the tank for detecting external discharges. This segmentation allows the system to distinguish between internal and external discharge sources by comparing signals from both sensors, thereby eliminating false positives caused by high-intensity external discharges.
2Loss of information
If ultrasound detectors are used to identify external partial discharges, then external discharge location can be determined, but the detectors are also sensitive to external noise other than partial discharge noise reducing reliability
Solution Approach 1:
The system changes the detection parameter from broadband acoustic detection to UHF electromagnetic signal detection. UHF sensors are specifically tuned to detect the electromagnetic radiation emitted by partial discharges in the 300 MHz to 3 GHz frequency range, which allows selective detection of discharge-related electromagnetic signals while filtering out other external noise sources that ultrasound detectors cannot distinguish.
3Loss of information
If ultraviolet cameras are used to detect partial discharges, then corona-type external discharges can be located, but other types of partial discharges cannot be detected and the equipment is very expensive
Solution Approach 1:
The UHF measurement system provides universal detection capability for all types of partial discharges regardless of their origin or mechanism. Unlike ultraviolet cameras that are limited to corona-type discharges, UHF sensors can detect electromagnetic radiation from any partial discharge source including internal discharges, external discharges, corona discharges, and switching discharges, making the system multi-functional and adaptable to various discharge types.
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 approach allows for reliable and accurate differentiation between internal and external partial discharges, reducing false positives and improving detection reliability and cost-effectiveness.
Implementation Method 1
a first UHF measurement system that includes a first UHF sensor inserted completely or partly into the tank and that delivers a UHF signal whenever a partial discharge occurs
Data Source
AI summary
The invention relates to detection apparatus for detecting a partial discharge from live electrical apparatus, the detection apparatus comprising detection means (Pc) mounted on the live electrical apparatus (T) for the purpose of detecting the occurrence of at least one partial discharge, wherein said detection apparatus further comprises additional means (D1, D2, S) suitable for determining whether a detected partial discharge is internal or external relative to the live apparatus.