2007 IEEE International Conference on Solid Dielectrics, 2007
Using an integrated measurement system, partial discharge activity has been recorded simultaneous... more Using an integrated measurement system, partial discharge activity has been recorded simultaneously on a pulse-by-pulse basis in terms of radiated radio-frequency (RF) pulse energy and the apparent charge measured according to IEC60270. Plotting the energy of the RF pulses against the corresponding apparent charge produces a correlation that will be sensitive to the shape of the underlying current pulse, which would be expected to vary depending on the type and severity of the defect. This paper presents combined measurements for several resin insulation samples containing a number of voids of known dimensions. Results indicate that using a combined measurement strategy, it may be possible to discriminate between discharge activity occurring in each void based on the correlation between apparent charge and RF energy.
Partial discharges may occur in defective insulation systems of high voltage equipment, such as g... more Partial discharges may occur in defective insulation systems of high voltage equipment, such as gas insulated substations and power transformers. These discharges generate electromagnetic waves that can be detected using ultrahigh frequency (UHF) sensors. UHF sensors must meet certain sensitivity criteria over a wide frequency range so as to be capable of detecting small discharges. Sensor frequency response is measured using a gigahertz transverse electromagnetic calibration system. Previous research has shown that finite-difference time-domain (FDTD) simulation of the calibration process can accurately model the response of the existing sensors. The work reported here demonstrates how a new sensor can be designed entirely using FDTD modeling. The proposed new partial discharge sensor has a physical construction that was selected to make it more robust, simple to manufacture, and convenient to install on metal-clad high-voltage apparatus. The internal structure of the UHF sensor was developed and optimized entirely within the FDTD software domain before the physical device was manufactured and tested. Simulated and experimental calibration results were found to be in agreement to within 10%. This finding validates the design methodology and optimization process. The approach described in this paper will help to streamline the design of UHF partial discharge sensors for specific applications in future.
2008 International Conference on Condition Monitoring and Diagnosis, 2008
UHF methods for locating partial discharges (PD) in power transformers are under development and ... more UHF methods for locating partial discharges (PD) in power transformers are under development and are increasingly being applied in the field. Due to the complexity and variation of internal structures in power transformers, a useful starting point is to assess the accuracy of PD location in a simple environment. Therefore, tests have been carried out in a metal tank to
Describes the correlation between RF energy and IEC60270 apparent charge for selected partial dis... more Describes the correlation between RF energy and IEC60270 apparent charge for selected partial discharge source geometries
11th International Symposium on High-Voltage Engineering (ISH 99), 1999
An attenuation survey was carried out for UHF signals in a 400 kV gas insulated substation (GIS).... more An attenuation survey was carried out for UHF signals in a 400 kV gas insulated substation (GIS). The GIS is fitted with UHF couplers that form part of a partial discharge monitoring system. An impulse train generator was used to inject 15 V impulses into the couplers at a repetition rate of 100 MHz. The output signals at couplers further along the GIS were recorded using a spectrum analyser. Signal attenuation was calculated by summing the input and output powers for each harmonic. Differences in attenuation between the three phases are evaluated. Results confirm that the losses cannot be accounted for simply by assigning a fixed attenuation to each GIS component. However, the spread of the measurements was less than might be expected for such a wide variation in signal paths.
2007 Electrical Insulation Conference and Electrical Manufacturing Expo, 2007
The IEC60270 standard has become the key reference for general measurement of partial discharge (... more The IEC60270 standard has become the key reference for general measurement of partial discharge (PD) in high voltage. This paper discusses the need to include reference to radiated emissions within this standard alongside the additional PD detection techniques outlined in the Annex. The paper suggests that the Annex should in the future also make reference to combined simultaneous IEC60270 and RF measurement systems allowing traditional apparent charge measurements to be complimented by knowledge of the radiated signals. The issues of RF calibration through the deployment of a combined measurement system are also discussed as well as the potential of a combined apparent charge and RF system to help further identify basic PD fault types.
2007 Electrical Insulation Conference and Electrical Manufacturing Expo, 2007
... 10017L...-_ _...J..-_ _--I-_ _~_ _____...JL__ _....._ __' o 2 3 4 6 Apparent... more ... 10017L...-_ _...J..-_ _--I-_ _~_ _____...JL__ _....._ __' o 2 3 4 6 Apparent Charge (pC) lI. ... Of course the frequency content may change as the void deteriorates under stress, resulting in different charge redistribution and eventually breakdown, but the precise nattu'e ofthe ...
Conference Record of the the 2002 IEEE International Symposium on Electrical Insulation (Cat. No.02CH37316)
A novel test cell is described, which is capable of providing a consistent level of partial disch... more A novel test cell is described, which is capable of providing a consistent level of partial discharge (PD) for generating UHF signals in GIS. The cell can be used to determine the sensitivity of UHF PD detection equipment. SF/sub 6/ gas is not required and the device can operate from a low-current DC supply at less than 1 kV. Its use is demonstrated in the testing of a new method for coupling UHF signals using a sensor designed to fit the test injection loop terminals of current transformers. The experiments demonstrate that contact discharges in the cell generate suitably broadband signals and show that the coupler is capable of achieving a PD detection sensitivity of <5 pC.
Enhanced condition monitoring of the electric grid infrastructure could be achieved by adding mor... more Enhanced condition monitoring of the electric grid infrastructure could be achieved by adding more sensors to track the plant health more accurately. However, the installation or operating costs of any additional sensors could outweigh the benefits they bring due to the requirements for new cabling or battery maintenance. High voltage plant, such as substation, contains several potential energy sources. Harvesting
Conference Record of the the 2002 IEEE International Symposium on Electrical Insulation (Cat. No.02CH37316)
This paper describes an online monitoring system which detects both partial discharges and the un... more This paper describes an online monitoring system which detects both partial discharges and the underlying power frequency leakage current on an insulator surface. This could allow degradation of the insulator performance to be monitored remotely. The sensing element would be a metal band fitted around the insulator close to the earthed terminal. High and low frequency components of current are separated and recorded in order that trends can be observed. A pollution model was devised which replicated the deposition of surface contamination on insulators in a practical laboratory experiment. The effectiveness of the experimental technique for detecting pollution build up was studied using this arrangement.
2014 IEEE International Instrumentation and Measurement Technology Conference (I2MTC) Proceedings, 2014
Partial discharge (PD) measurement is an established high voltage insulation monitoring technique... more Partial discharge (PD) measurement is an established high voltage insulation monitoring technique used to facilitate the detection of incipient faults in high voltage apparatus. Based on the great importance of the power system, is constant the research about the nature and characteristics of PD sources. A low-cost, free-standing, radiometric, partial discharge wireless sensor network (PD WSN) is described for application to real-time condition monitoring, asset management and operations optimization in the future smart grid. The proposed PD WSN is based on a novel approach to PD location which obviates the need for synchronization between sensors thereby improving scalability. In this paper, the progress in the development of a PD WSN prototype is described. For the proposed evaluation of PD signals, several measurements were performed using a diskcone antenna and a commercial system based on the IEC 60270 standard. Early progress in the development of components for a PD detection system using a network of free-standing radiometers for monitoring of electricity substations has been also presented.
2008 International Symposium on Electromagnetic Compatibility - EMC Europe, 2008
A TEM half-horn antenna has been designed and constructed for the detection impulsive noise. The ... more A TEM half-horn antenna has been designed and constructed for the detection impulsive noise. The particular application of interest is the recording of partial discharge and/or sferic radiation in a 400 kV electricity transmission substation. The characteristics and performance of the half-horn are presented. Laboratory verification of the antenna&amp;#39;s utility for the detection partial discharge has been carried out using
ABSTRACT Using a newly developed measurement system, partial discharge (PD) activity has been rec... more ABSTRACT Using a newly developed measurement system, partial discharge (PD) activity has been recorded simultaneously on a pulse-by-pulse basis in terms of radiated radio frequency (RF) energy and the conducted apparent charge measured according to the IEC60270 standard. Two epoxy resin insulation samples containing voids have been activated separately and in parallel and the resulting PD was measured using the combined system. It has been shown that the combined measurement system has the ability to distinguish between discharges occurring simultaneously in each of the respective samples. This is evident in the appearance of separate clusters when the energy of the radio frequency discharge signal is plotted against the apparent charge for a large number of pulses. The identity of the defect producing each cluster has been confirmed by modelling the complete response of a gas-insulated-switchgear chamber to simulated Gaussian current pulses of known charge. The combined technique has also shown potential to distinguish between additional simultaneously active defects, including free metallic particles in oil. The combination of the two measurement systems may enable the classification of PD activity with a greater degree of confidence than conventional phase-resolved measurements allow when more than one defect is present.
2007 IEEE International Conference on Solid Dielectrics, 2007
Using an integrated measurement system, partial discharge activity has been recorded simultaneous... more Using an integrated measurement system, partial discharge activity has been recorded simultaneously on a pulse-by-pulse basis in terms of radiated radio-frequency (RF) pulse energy and the apparent charge measured according to IEC60270. Plotting the energy of the RF pulses against the corresponding apparent charge produces a correlation that will be sensitive to the shape of the underlying current pulse, which would be expected to vary depending on the type and severity of the defect. This paper presents combined measurements for several resin insulation samples containing a number of voids of known dimensions. Results indicate that using a combined measurement strategy, it may be possible to discriminate between discharge activity occurring in each void based on the correlation between apparent charge and RF energy.
Partial discharges may occur in defective insulation systems of high voltage equipment, such as g... more Partial discharges may occur in defective insulation systems of high voltage equipment, such as gas insulated substations and power transformers. These discharges generate electromagnetic waves that can be detected using ultrahigh frequency (UHF) sensors. UHF sensors must meet certain sensitivity criteria over a wide frequency range so as to be capable of detecting small discharges. Sensor frequency response is measured using a gigahertz transverse electromagnetic calibration system. Previous research has shown that finite-difference time-domain (FDTD) simulation of the calibration process can accurately model the response of the existing sensors. The work reported here demonstrates how a new sensor can be designed entirely using FDTD modeling. The proposed new partial discharge sensor has a physical construction that was selected to make it more robust, simple to manufacture, and convenient to install on metal-clad high-voltage apparatus. The internal structure of the UHF sensor was developed and optimized entirely within the FDTD software domain before the physical device was manufactured and tested. Simulated and experimental calibration results were found to be in agreement to within 10%. This finding validates the design methodology and optimization process. The approach described in this paper will help to streamline the design of UHF partial discharge sensors for specific applications in future.
2008 International Conference on Condition Monitoring and Diagnosis, 2008
UHF methods for locating partial discharges (PD) in power transformers are under development and ... more UHF methods for locating partial discharges (PD) in power transformers are under development and are increasingly being applied in the field. Due to the complexity and variation of internal structures in power transformers, a useful starting point is to assess the accuracy of PD location in a simple environment. Therefore, tests have been carried out in a metal tank to
Describes the correlation between RF energy and IEC60270 apparent charge for selected partial dis... more Describes the correlation between RF energy and IEC60270 apparent charge for selected partial discharge source geometries
11th International Symposium on High-Voltage Engineering (ISH 99), 1999
An attenuation survey was carried out for UHF signals in a 400 kV gas insulated substation (GIS).... more An attenuation survey was carried out for UHF signals in a 400 kV gas insulated substation (GIS). The GIS is fitted with UHF couplers that form part of a partial discharge monitoring system. An impulse train generator was used to inject 15 V impulses into the couplers at a repetition rate of 100 MHz. The output signals at couplers further along the GIS were recorded using a spectrum analyser. Signal attenuation was calculated by summing the input and output powers for each harmonic. Differences in attenuation between the three phases are evaluated. Results confirm that the losses cannot be accounted for simply by assigning a fixed attenuation to each GIS component. However, the spread of the measurements was less than might be expected for such a wide variation in signal paths.
2007 Electrical Insulation Conference and Electrical Manufacturing Expo, 2007
The IEC60270 standard has become the key reference for general measurement of partial discharge (... more The IEC60270 standard has become the key reference for general measurement of partial discharge (PD) in high voltage. This paper discusses the need to include reference to radiated emissions within this standard alongside the additional PD detection techniques outlined in the Annex. The paper suggests that the Annex should in the future also make reference to combined simultaneous IEC60270 and RF measurement systems allowing traditional apparent charge measurements to be complimented by knowledge of the radiated signals. The issues of RF calibration through the deployment of a combined measurement system are also discussed as well as the potential of a combined apparent charge and RF system to help further identify basic PD fault types.
2007 Electrical Insulation Conference and Electrical Manufacturing Expo, 2007
... 10017L...-_ _...J..-_ _--I-_ _~_ _____...JL__ _....._ __&amp;amp;#x27; o 2 3 4 6 Apparent... more ... 10017L...-_ _...J..-_ _--I-_ _~_ _____...JL__ _....._ __&amp;amp;#x27; o 2 3 4 6 Apparent Charge (pC) lI. ... Of course the frequency content may change as the void deteriorates under stress, resulting in different charge redistribution and eventually breakdown, but the precise nattu&amp;amp;#x27;e ofthe ...
Conference Record of the the 2002 IEEE International Symposium on Electrical Insulation (Cat. No.02CH37316)
A novel test cell is described, which is capable of providing a consistent level of partial disch... more A novel test cell is described, which is capable of providing a consistent level of partial discharge (PD) for generating UHF signals in GIS. The cell can be used to determine the sensitivity of UHF PD detection equipment. SF/sub 6/ gas is not required and the device can operate from a low-current DC supply at less than 1 kV. Its use is demonstrated in the testing of a new method for coupling UHF signals using a sensor designed to fit the test injection loop terminals of current transformers. The experiments demonstrate that contact discharges in the cell generate suitably broadband signals and show that the coupler is capable of achieving a PD detection sensitivity of <5 pC.
Enhanced condition monitoring of the electric grid infrastructure could be achieved by adding mor... more Enhanced condition monitoring of the electric grid infrastructure could be achieved by adding more sensors to track the plant health more accurately. However, the installation or operating costs of any additional sensors could outweigh the benefits they bring due to the requirements for new cabling or battery maintenance. High voltage plant, such as substation, contains several potential energy sources. Harvesting
Conference Record of the the 2002 IEEE International Symposium on Electrical Insulation (Cat. No.02CH37316)
This paper describes an online monitoring system which detects both partial discharges and the un... more This paper describes an online monitoring system which detects both partial discharges and the underlying power frequency leakage current on an insulator surface. This could allow degradation of the insulator performance to be monitored remotely. The sensing element would be a metal band fitted around the insulator close to the earthed terminal. High and low frequency components of current are separated and recorded in order that trends can be observed. A pollution model was devised which replicated the deposition of surface contamination on insulators in a practical laboratory experiment. The effectiveness of the experimental technique for detecting pollution build up was studied using this arrangement.
2014 IEEE International Instrumentation and Measurement Technology Conference (I2MTC) Proceedings, 2014
Partial discharge (PD) measurement is an established high voltage insulation monitoring technique... more Partial discharge (PD) measurement is an established high voltage insulation monitoring technique used to facilitate the detection of incipient faults in high voltage apparatus. Based on the great importance of the power system, is constant the research about the nature and characteristics of PD sources. A low-cost, free-standing, radiometric, partial discharge wireless sensor network (PD WSN) is described for application to real-time condition monitoring, asset management and operations optimization in the future smart grid. The proposed PD WSN is based on a novel approach to PD location which obviates the need for synchronization between sensors thereby improving scalability. In this paper, the progress in the development of a PD WSN prototype is described. For the proposed evaluation of PD signals, several measurements were performed using a diskcone antenna and a commercial system based on the IEC 60270 standard. Early progress in the development of components for a PD detection system using a network of free-standing radiometers for monitoring of electricity substations has been also presented.
2008 International Symposium on Electromagnetic Compatibility - EMC Europe, 2008
A TEM half-horn antenna has been designed and constructed for the detection impulsive noise. The ... more A TEM half-horn antenna has been designed and constructed for the detection impulsive noise. The particular application of interest is the recording of partial discharge and/or sferic radiation in a 400 kV electricity transmission substation. The characteristics and performance of the half-horn are presented. Laboratory verification of the antenna&amp;#39;s utility for the detection partial discharge has been carried out using
ABSTRACT Using a newly developed measurement system, partial discharge (PD) activity has been rec... more ABSTRACT Using a newly developed measurement system, partial discharge (PD) activity has been recorded simultaneously on a pulse-by-pulse basis in terms of radiated radio frequency (RF) energy and the conducted apparent charge measured according to the IEC60270 standard. Two epoxy resin insulation samples containing voids have been activated separately and in parallel and the resulting PD was measured using the combined system. It has been shown that the combined measurement system has the ability to distinguish between discharges occurring simultaneously in each of the respective samples. This is evident in the appearance of separate clusters when the energy of the radio frequency discharge signal is plotted against the apparent charge for a large number of pulses. The identity of the defect producing each cluster has been confirmed by modelling the complete response of a gas-insulated-switchgear chamber to simulated Gaussian current pulses of known charge. The combined technique has also shown potential to distinguish between additional simultaneously active defects, including free metallic particles in oil. The combination of the two measurement systems may enable the classification of PD activity with a greater degree of confidence than conventional phase-resolved measurements allow when more than one defect is present.
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Papers by Martin D Judd