Partial Discharge Measurement Device with Bipolar Electrodes
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Solution Overview
Problem
Conventional partial discharge measurement devices are bulky due to the required insulating distance in air and high voltages, making them cumbersome and inefficient for compact applications.
Innovation Solution
A measuring device with first and second voltage sources applying alternating voltages of the same amplitude but 180° out of phase, allowing for compact design and using broadband sensors to detect current pulses via electromagnetic fields or voltage drops across measurement impedances, with protective resistors to prevent damage during measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional measuring devices use single-electrode configuration with high voltage (1 kV to several 100 kV) and air insulation, then measurement reliability is ensured, but device dimensions become large (meter range) and device complexity increases
Solution Approach 1:
The single high-voltage electrode is segmented into two electrodes with opposite polarity. Each electrode operates at half the required potential difference with respect to ground, allowing the use of smaller insulation distances and reducing the overall dimensions of the Faraday cage while maintaining the necessary electric field strength for reliable partial discharge measurement.
Solution Approach 2:
Both electrodes are maintained at equal but opposite potentials relative to ground (equipotential symmetry). This symmetric voltage distribution allows for compact insulation design since neither electrode requires the full potential difference distance from ground, enabling a more compact Faraday cage structure.
2Device complexity
If single electrode configuration is used, then device complexity is reduced, but measurement precision decreases due to inability to perform phase-sensitive detection
Solution Approach 1:
The measurement function is segmented between two electrodes, each equipped with its own broadband sensor. This allows independent detection of partial discharge signals from both electrodes, enabling phase-sensitive analysis where the 180° phase difference between electrodes can be exploited to distinguish true partial discharge signals from background noise, thereby improving measurement precision.
Solution Approach 2:
The signals from both electrodes are processed in a correlated manner, using the known 180° phase relationship as a reference. By comparing the phase and amplitude of signals from both electrodes, the system can selectively enhance genuine partial discharge signals while suppressing interference, improving measurement precision through phase-sensitive detection.
3Reliability
If high voltage is applied to single electrode, then partial discharge measurement capability is achieved, but harmful interference increases
Solution Approach 1:
The system uses asymmetric signal processing despite symmetric electrode configuration. By applying different reference phases to signals from the two electrodes (0° for one, 180° for the other) during correlation processing, genuine partial discharge signals constructively interfere while random electromagnetic interference destructively interferes, reducing harmful interference through phase-sensitive detection.
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 configuration enables accurate and compact measurement of partial discharges in insulating liquids, reducing interference and improving measurement accuracy by allowing simultaneous phase-sensitive detection at both electrodes, while maintaining safety through protective resistors.
Implementation Method 1
first and second voltage sources with which an alternating voltage relative to ground potential can be applied to the first and to the second electrode
Implementation Method 2
These current pulses can advantageously be detected contactlessly by the (respective) broadband sensor, for example by means of a Rogowski coil or by means of a Hall sensor or by means of an antenna which receives an electromagnetic field caused by the current pulses
Implementation Method 3
It is known to arrange measuring devices for measuring partial discharges in Faraday cages in order to shield against interference
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
The device has two electrodes (13, 14) arranged in a container that contains isolation fluids to be measured, where voltage is supplied between the electrodes. Wideband sensors (26, 27) output a measured value for partial discharge in the isolation fluid. The container with the electrodes is arranged within a Faraday cage (34). Two voltage sources (15, 16) supply alternating current (AC) voltages to the electrodes with respect to an earth potential (19), where the supplied AC voltages have same amplitudes and are phase-delayed about 180 degrees against each other. An independent claim is also included for a method for measuring partial discharge in isolation fluids.