Mohd Hafizi Ahmad | Universiti Teknologi Malaysia - UTM (original) (raw)

Papers by Mohd Hafizi Ahmad

In case of medium voltage cables, the main cause of the insulation breakdown is water treeing by ... more In case of medium voltage cables, the main cause of the insulation breakdown is water treeing by referring to the report of national power utility of Malaysia, Tenaga Nasional Berhad (TNB). The inconsistent and unreliable nature brings out the importance of research towards water tree detection of polymeric insulating cable. Early detection of water tree in underground polymeric cable is important in order to increase the cable efficiency by reducing the timeframe of the cable failure. From the previous research of water tree detection, the types of needle that have been used are metal and nickel. It was found that the usage of these needles has some weaknesses which lead to inefficiency of water tree detection. Corrosion, losses and corona discharge are some of the significant problems faced by using those materials. In addition to that, it was found that the time was taken longer using the previous method of water tree detection. Thus, in order to reduce the time of water tree detection and preventing the material's physical failures, an improved method is proposed. Also, this paper presents the propensity difference of water tree detection in two different insulating materials namely cross-linked polyethylene (XLPE) and low-density polyethylene (LDPE). With the data and research being studied carefully, the water tree detection will be much easier to detect. The effect of ageing time in water tree detection was also discussed in this paper.

TELKOMNIKA Indonesian Journal of Electrical Engineering

Nowadays, the most widely used insulating materials in high voltage equipment such as cables are ... more Nowadays, the most widely used insulating materials in high voltage equipment such as cables are polymeric insulations due to the numerous merits they possess with regards to electrical performance compared to paper insulations. However, electrical treeing, one of the dielectric pre-breakdown phenomena, has been considered as a major contribution to the failure of insulating polymeric materials. Thus, this paper provides an overview on the factors affecting the initiation and propagation of electrical tree. Discussions on parameters that affect the growth of electrical treeing such as applied voltage, electric field enhancement, partial discharge, frequency of applied voltage and temperature are given. Some discussions on the various models are also highlighted. The tree related models being discussed herein include Weibull, Lognormal, Johnson SB, Dielectric Breakdown Model, Discharge-Avalanche Model, and Field-Driven Tree Growth. In addition, discussions on the use of nano-sized fillers in polymeric insulating material to inhibit electric treeing are highlighted.

Carbon Nanotubes (CNTs) are generally nano-scale tubes comprising a network of carbon atoms in a ... more Carbon Nanotubes (CNTs) are generally nano-scale tubes comprising a network of carbon atoms in a cylindrical setting that compared with silicon counterparts present outstanding characteristics such as high mechanical strength, high sensing capability and large surface-to-volume ratio. These characteristics, in addition to the fact that CNTs experience changes in their electrical conductance when exposed to different gases, make them appropriate candidates for use in sensing/measuring applications such as gas detection devices. In this research, a model for a Field Effect Transistor (FET)-based structure has been developed as a platform for a gas detection sensor in which the CNT conductance change resulting from the chemical reaction between NH 3 and CNT has been employed to model the sensing mechanism with proposed sensing parameters. The research implements the same FET-based structure as in the work of Peng et al. on nanotube-based NH 3 gas

27th Regional Conference on Solid State Science and Technology, 20-22 December 2013, Kota Kinabalu, Sabah, Malaysia.

IEEE International Conference on Electrical Insulation and Dielectric Phenomena (CEIDP2013), Shenzhen, China, October 20-23, pp. 498-501, 2013.

Electrical tree is recognized as one of the pre-breakdown phenomena that occurs in high voltage i... more Electrical tree is recognized as one of the pre-breakdown phenomena that occurs in high voltage insulation material. In addition, under high divergent field, the electrical tree grows rapidly and severely which may cause the breakdown of insulation to occur. In view of foregoing, nano-filler was added into the base insulating materials to enhance their properties against the growth of electrical tree. Thus in this study, nano-titanium dioxide was chosen as filler in order to improve the characteristics of silicone rubber which in turn inhibits the growth of electrical tree. The test samples were prepared in the form of leaf-like specimen. Nano-titanium dioxide was chosen as filler in order to improve the characteristics of silicone rubber. The number of partial discharge occurrence, partial discharge magnitude and breakdown time of the nanocomposites were investigated under different percentage of nano-titanium dioxide. The applied voltage and frequency were fixed at 10 kVrms AC and 50 Hz respectively. Treeing growth was recorded and partial discharge was observed at the constant applied voltage. The findings in this research showed that under high concentration of nano titanium dioxide, the treeing propagation were reduced and partial discharge number increased. The function of nano titanium dioxide as obstacle for the tree path in the silicone rubber samples was successfully tested. The results have shown that physical bonding between nano-titanium dioxide and silicone rubber matrix was improved, the tree propagation speed decreased, and this resulted in the increment of partial discharge magnitude. However, further experimentation is required to give more clarifications regarding to this finding.

2013 Annual Report Conference on Electrical Insulation and Dielectric Phenomena (CEIDP), pp. 502-505, Oct 20, 2013

Electrical tree initiation voltage and tree propagation length for unfilled silicone rubber, sili... more Electrical tree initiation voltage and tree propagation length for unfilled silicone rubber, silicone rubber nanocomposites filled with 1% and 3% of OMMT and SiO2 was presented in this paper. This study investigates the capabilities of OMMT and SiO2 in silicone rubber in order to inhibit the growth of electrical treeing. From the result of this study has indicated that in the filled nanocomposite sample, the OMMT acts as barrier to unfilled silicone rubber and silicone rubber filled with SiO2 because the capabilities to decreased the tree propagation length of electrical tree. This result revealed that OMMT could be used as filler in silicone rubber insulating material for the purpose of retarding electrical tree growth.

IEEE International Conference On Electrical Insulation And Dielectric Phenomena (CEIDP2013), Oct 20, 2013

Phase resolved partial discharge (PD) data have been recorded from electrical trees grown in a fl... more Phase resolved partial discharge (PD) data have been recorded from electrical trees grown in a flexible epoxy resin, a silicone gel and a silicone rubber with and without a nanofiller. The epoxy resin samples and silicone gel samples did not contain any filler particles. In the case of silicone rubber, organo-Montmorillonite (oMMT) nanofiller, was used. The electrical treeing experiments were carried out at different temperatures in the range 20-60°C. The details of PD dynamics during the electrical tree growth have been found to change significantly with temperature in some of the polymer systems investigated. An attempt is made to identify features which are present in the PD patterns irrespective of the host polymer matrix using PSA plots and unique to the partial discharge process in electrical trees. Such features can be used for reliable diagnostics and condition monitoring of real-life electrical insulation systems.

Proceedings of National Science Postgraduate Conference (NSPC2011), Johor Bahru, 15-17 November, pp. 625-630, 2011.

4th Electrical and Electronics Postgraduate Colloquium, Aug 20, 2013

IEEE International Conference on Solid Dielectrics (ICSD2013), pp. 816-819, Jul 4, 2013

This paper describes a set of experiments to assess temperature dependence on phase-resolved part... more This paper describes a set of experiments to assess temperature dependence on phase-resolved partial discharge activity during electrical tree growth in a room temperature vulcanized silicone rubber/organo-Montmorillonite (oMMT) nanocomposite material. The filler particles were prepared by treating MMT with alkylammonium before dispersing in the silicone rubber to form the silicone/organo-Montmorillonite nanocomposite. The samples were prepared with three levels of nanofiller content, 0% by wt, 1% by wt and 3% by wt in order to assess the effect of different filler concentrations on the treeing process and the corresponding PD activity under an applied 50Hz AC electrical stress. The results demonstrate that the introduction of 1% by wt of nano-filler increases the tree inception times and decreases the rate of tree growth. It was also found that the PD characteristics, particularly the mean phase angle of occurrence of the positive and negative discharge distributions, became insensitive to variations in temperature. This reflects an enhanced stability in the nanocomposite electrical properties compared with the base polymer. Tree initiation and growth were found to be suppressed in the case of the 3% by wt nanocomposite to the extent that tree growth did not occur over the duration of the test (4 hours).

The 2011 2nd Fiqh Science and Technology Seminar

Journal of Electrical Engineering and Technology (JEET), Vol. 8. No. 4, pp. 840-849, 2013.

This paper presents a statistical approach to analyze electrical tree inception voltage,electrica... more This paper presents a statistical approach to analyze electrical tree inception voltage,electrical tree breakdown voltage and tree breakdown time of unsaturated polyester resin subjected to AC voltage. The aim of this work was to show that Weibull and lognormal distribution may not be the most suitable distributions for analysis of electrical treeing data. In this paper, an investigation of statistical distributions of electrical tree inception voltage, electrical tree breakdown voltage and breakdown time data was performed on 108 leaf-like specimen samples. Revelations from the test results showed that Johnson SB distribution is the best fit for electrical tree inception voltage and tree breakdown time data while electrical tree breakdown voltage data is best suited with Wakeby distribution. The fitting step was performed by means of Anderson-Darling (AD) Goodness-of-fit test (GOF). Based on the fitting results of tree inception voltage, tree breakdown time and tree breakdown voltage data, Johnson SB and Wakeby exhibit the lowest error value respectively compared to Weibull and lognormal.

International Conference on Nanoscience and Nanotechnology (NanoSciTech), Mar 4, 2013

Jurnal Teknologi, Vol. 64, No. 4, pp. 23–26, 2013.

This paper presents the results of the study on the electrical tree growth of organo-montmorillon... more This paper presents the results of the study on the electrical tree growth of organo-montmorillonite (OMMT) nanofillers in silicone rubber under ac ramp voltage of 0.5 kV per second. This study investigates the ability of OMMT to retard the growth of electrical tree in silicone rubber. Samples of silicone rubber nanocomposites (two filled with 1% and 3% OMMT respectfully while the third is unfilled silicone rubber), were used in this experimental study and the growth rate of the electrical tree and its length were observed in both samples. .The result of this study has revealed that in the filled nanocomposite sample, the OMMT acts as barrier which slows down the growth rate of electrical tree. This makes OMMT a potential material to use as fillers in polymeric insulations for the purpose of retarding electrical tree growth.

Jurnal Teknologi, Vol. 64, No. 4, pp. 103–107, 2013.

This paper discusses the effects of nanofiller on electrical treeing growth in polymer nanocompo... more This paper discusses the effects of nanofiller on electrical treeing growth in polymer nanocomposites. The polymer nanocomposite consists of epoxy resin as the base polymer and organo-montmorillonite as the nanofiller. The influence of this nanofiller on the electrical treeing breakdown resistance was investigated experimentally. The quantity of organo-montmorillonite were added in epoxy resin by ultrasonication method based on weight percentage (wt%). The weight percentages used in this experiment were 0 wt% and 1 wt%, respectively. All the samples were produced in the form of leaf-like specimens which were categorized into two parts: unfilled sample (0 wt%) and filled sample (1 wt%). Point-to-plane samples were subjected to 0.5 kVrms/s HVAC ramp voltage. The data of tree inception voltage and tree breakdown voltage were collected and comparative results were made and presented. The morphological analysis of epoxy nanocomposites were investigated using field emission scanning electron microscopy (FESEM). Electrical tree parameters analysis has shown that the existence of organo-montmorillonite in epoxy resin could exhibit significant improvement of tree characteristics of epoxy resin nanocomposites as the nanofiller contributed to the increase of tree inception voltage and tree breakdown voltage.

IEEE International Conference on Power and Energy (PECON2012), 2-5 December, Kota Kinabalu, Malaysia, pp. 712-715, 2012

"This paper presents the results of the study on the performance of organo­montmorill... more "This paper presents the results of the study on the performance of organo­montmorillonite (OMMT) nanofillers in silicone rubber under high voltage application focusing on the ability of the OMMT to retard the growth of electrical tree in silicone rubber. Treeing experiments were conducted at a ramp ac voltage of 0.5 kV per second on unfilled silicone rubber samples as well as filled silicone rubber nanocomposites with 1 % weight percentage of OMMT. Tree inception voltage as well as tree length were observed on the filled and unfilled samples. In addition the morphological characteristics of the samples were investigated using Field Emission Scanning Electron Microscopy (FESEM) .
The result of this study revealed that OMMT inhibited electrical tree growth thus suggesting OMMT can be a potential material for use as filler in polymeric insulation for tree growth retardation. "

Annual Report of Conference on Electrical Insulation and Dielectric Phenomena (CEIDP2012) Montreal, Canada, October 14-17, 2012, pp. 898-901.

Electrical treeing is one of the main reasons for failure of polymeric materials used in high vol... more Electrical treeing is one of the main reasons for failure of polymeric materials used in high voltage applications. Treeing is observed to originate at points where impurities, voids, defects, or conducting projections cause excessive local electric field stress in the dielectric. It has been proposed that nanofillers could be employed as an electrical tree inhibitor in polymeric insulating materials. With development of nanotechnology, polymer nanocomposites have drawn much attention, because they are expected to have improved mechanical, thermal and electrical properties over the neat polymer. In this paper, modified nanoclay was used to examine the initiation and propagation of electrical treeing. Effects of electrical treeing on nanocomposites insulating material filled with 1 wt% and 3 wt% of Organo-Montmorillonite (OMMT) were used in this work. The results have shown that electrical tree growth was suppressed in silicone rubber nanocomposites compared with neat silicone rubber which allowed a faster growth of electrical treeing. However, more studies should be carried out with different nanofiller/silicone ratios to see in further enhancements in tree inhibition could be achieved.

International Journal of Electronics and Electrical Engineering , Vol. 6, 2012, pp. 213-218

""""The use of synthetic retardants in polymeric insulated cables is not uncommon in the high vo... more """"The use of synthetic retardants in polymeric insulated
cables is not uncommon in the high voltage engineering to study
electrical treeing phenomenon. However few studies on organic
materials for the same investigation have been carried. .This paper
describes the study on the effects of Oil Palm Empty Fruit Bunch
(OPEFB) microfiller on the tree initiation and propagation in silicone rubber with different weight percentages (wt %) of filler to insulation bulk material. The weight percentages used were 0 wt % and 1 wt % respectively. It was found that the OPEFB retards the propagation of the electrical treeing development. For tree inception study, the addition of 1(wt %) OPEFB has increase the tree inception voltage of silicone rubber. So, OPEFB is a potential retardant to the initiation and growth of electrical treeing occurring in polymeric materials for high voltage application. However more studies on the effects of physical and electrical properties of OPEFB as a tree retardant material are required. """"

In case of medium voltage cables, the main cause of the insulation breakdown is water treeing by ... more In case of medium voltage cables, the main cause of the insulation breakdown is water treeing by referring to the report of national power utility of Malaysia, Tenaga Nasional Berhad (TNB). The inconsistent and unreliable nature brings out the importance of research towards water tree detection of polymeric insulating cable. Early detection of water tree in underground polymeric cable is important in order to increase the cable efficiency by reducing the timeframe of the cable failure. From the previous research of water tree detection, the types of needle that have been used are metal and nickel. It was found that the usage of these needles has some weaknesses which lead to inefficiency of water tree detection. Corrosion, losses and corona discharge are some of the significant problems faced by using those materials. In addition to that, it was found that the time was taken longer using the previous method of water tree detection. Thus, in order to reduce the time of water tree detection and preventing the material's physical failures, an improved method is proposed. Also, this paper presents the propensity difference of water tree detection in two different insulating materials namely cross-linked polyethylene (XLPE) and low-density polyethylene (LDPE). With the data and research being studied carefully, the water tree detection will be much easier to detect. The effect of ageing time in water tree detection was also discussed in this paper.

TELKOMNIKA Indonesian Journal of Electrical Engineering

Nowadays, the most widely used insulating materials in high voltage equipment such as cables are ... more Nowadays, the most widely used insulating materials in high voltage equipment such as cables are polymeric insulations due to the numerous merits they possess with regards to electrical performance compared to paper insulations. However, electrical treeing, one of the dielectric pre-breakdown phenomena, has been considered as a major contribution to the failure of insulating polymeric materials. Thus, this paper provides an overview on the factors affecting the initiation and propagation of electrical tree. Discussions on parameters that affect the growth of electrical treeing such as applied voltage, electric field enhancement, partial discharge, frequency of applied voltage and temperature are given. Some discussions on the various models are also highlighted. The tree related models being discussed herein include Weibull, Lognormal, Johnson SB, Dielectric Breakdown Model, Discharge-Avalanche Model, and Field-Driven Tree Growth. In addition, discussions on the use of nano-sized fillers in polymeric insulating material to inhibit electric treeing are highlighted.

Carbon Nanotubes (CNTs) are generally nano-scale tubes comprising a network of carbon atoms in a ... more Carbon Nanotubes (CNTs) are generally nano-scale tubes comprising a network of carbon atoms in a cylindrical setting that compared with silicon counterparts present outstanding characteristics such as high mechanical strength, high sensing capability and large surface-to-volume ratio. These characteristics, in addition to the fact that CNTs experience changes in their electrical conductance when exposed to different gases, make them appropriate candidates for use in sensing/measuring applications such as gas detection devices. In this research, a model for a Field Effect Transistor (FET)-based structure has been developed as a platform for a gas detection sensor in which the CNT conductance change resulting from the chemical reaction between NH 3 and CNT has been employed to model the sensing mechanism with proposed sensing parameters. The research implements the same FET-based structure as in the work of Peng et al. on nanotube-based NH 3 gas

27th Regional Conference on Solid State Science and Technology, 20-22 December 2013, Kota Kinabalu, Sabah, Malaysia.

IEEE International Conference on Electrical Insulation and Dielectric Phenomena (CEIDP2013), Shenzhen, China, October 20-23, pp. 498-501, 2013.

Electrical tree is recognized as one of the pre-breakdown phenomena that occurs in high voltage i... more Electrical tree is recognized as one of the pre-breakdown phenomena that occurs in high voltage insulation material. In addition, under high divergent field, the electrical tree grows rapidly and severely which may cause the breakdown of insulation to occur. In view of foregoing, nano-filler was added into the base insulating materials to enhance their properties against the growth of electrical tree. Thus in this study, nano-titanium dioxide was chosen as filler in order to improve the characteristics of silicone rubber which in turn inhibits the growth of electrical tree. The test samples were prepared in the form of leaf-like specimen. Nano-titanium dioxide was chosen as filler in order to improve the characteristics of silicone rubber. The number of partial discharge occurrence, partial discharge magnitude and breakdown time of the nanocomposites were investigated under different percentage of nano-titanium dioxide. The applied voltage and frequency were fixed at 10 kVrms AC and 50 Hz respectively. Treeing growth was recorded and partial discharge was observed at the constant applied voltage. The findings in this research showed that under high concentration of nano titanium dioxide, the treeing propagation were reduced and partial discharge number increased. The function of nano titanium dioxide as obstacle for the tree path in the silicone rubber samples was successfully tested. The results have shown that physical bonding between nano-titanium dioxide and silicone rubber matrix was improved, the tree propagation speed decreased, and this resulted in the increment of partial discharge magnitude. However, further experimentation is required to give more clarifications regarding to this finding.

2013 Annual Report Conference on Electrical Insulation and Dielectric Phenomena (CEIDP), pp. 502-505, Oct 20, 2013

Electrical tree initiation voltage and tree propagation length for unfilled silicone rubber, sili... more Electrical tree initiation voltage and tree propagation length for unfilled silicone rubber, silicone rubber nanocomposites filled with 1% and 3% of OMMT and SiO2 was presented in this paper. This study investigates the capabilities of OMMT and SiO2 in silicone rubber in order to inhibit the growth of electrical treeing. From the result of this study has indicated that in the filled nanocomposite sample, the OMMT acts as barrier to unfilled silicone rubber and silicone rubber filled with SiO2 because the capabilities to decreased the tree propagation length of electrical tree. This result revealed that OMMT could be used as filler in silicone rubber insulating material for the purpose of retarding electrical tree growth.

IEEE International Conference On Electrical Insulation And Dielectric Phenomena (CEIDP2013), Oct 20, 2013

Phase resolved partial discharge (PD) data have been recorded from electrical trees grown in a fl... more Phase resolved partial discharge (PD) data have been recorded from electrical trees grown in a flexible epoxy resin, a silicone gel and a silicone rubber with and without a nanofiller. The epoxy resin samples and silicone gel samples did not contain any filler particles. In the case of silicone rubber, organo-Montmorillonite (oMMT) nanofiller, was used. The electrical treeing experiments were carried out at different temperatures in the range 20-60°C. The details of PD dynamics during the electrical tree growth have been found to change significantly with temperature in some of the polymer systems investigated. An attempt is made to identify features which are present in the PD patterns irrespective of the host polymer matrix using PSA plots and unique to the partial discharge process in electrical trees. Such features can be used for reliable diagnostics and condition monitoring of real-life electrical insulation systems.

Proceedings of National Science Postgraduate Conference (NSPC2011), Johor Bahru, 15-17 November, pp. 625-630, 2011.

4th Electrical and Electronics Postgraduate Colloquium, Aug 20, 2013

IEEE International Conference on Solid Dielectrics (ICSD2013), pp. 816-819, Jul 4, 2013

This paper describes a set of experiments to assess temperature dependence on phase-resolved part... more This paper describes a set of experiments to assess temperature dependence on phase-resolved partial discharge activity during electrical tree growth in a room temperature vulcanized silicone rubber/organo-Montmorillonite (oMMT) nanocomposite material. The filler particles were prepared by treating MMT with alkylammonium before dispersing in the silicone rubber to form the silicone/organo-Montmorillonite nanocomposite. The samples were prepared with three levels of nanofiller content, 0% by wt, 1% by wt and 3% by wt in order to assess the effect of different filler concentrations on the treeing process and the corresponding PD activity under an applied 50Hz AC electrical stress. The results demonstrate that the introduction of 1% by wt of nano-filler increases the tree inception times and decreases the rate of tree growth. It was also found that the PD characteristics, particularly the mean phase angle of occurrence of the positive and negative discharge distributions, became insensitive to variations in temperature. This reflects an enhanced stability in the nanocomposite electrical properties compared with the base polymer. Tree initiation and growth were found to be suppressed in the case of the 3% by wt nanocomposite to the extent that tree growth did not occur over the duration of the test (4 hours).

The 2011 2nd Fiqh Science and Technology Seminar

Journal of Electrical Engineering and Technology (JEET), Vol. 8. No. 4, pp. 840-849, 2013.

This paper presents a statistical approach to analyze electrical tree inception voltage,electrica... more This paper presents a statistical approach to analyze electrical tree inception voltage,electrical tree breakdown voltage and tree breakdown time of unsaturated polyester resin subjected to AC voltage. The aim of this work was to show that Weibull and lognormal distribution may not be the most suitable distributions for analysis of electrical treeing data. In this paper, an investigation of statistical distributions of electrical tree inception voltage, electrical tree breakdown voltage and breakdown time data was performed on 108 leaf-like specimen samples. Revelations from the test results showed that Johnson SB distribution is the best fit for electrical tree inception voltage and tree breakdown time data while electrical tree breakdown voltage data is best suited with Wakeby distribution. The fitting step was performed by means of Anderson-Darling (AD) Goodness-of-fit test (GOF). Based on the fitting results of tree inception voltage, tree breakdown time and tree breakdown voltage data, Johnson SB and Wakeby exhibit the lowest error value respectively compared to Weibull and lognormal.

International Conference on Nanoscience and Nanotechnology (NanoSciTech), Mar 4, 2013

Jurnal Teknologi, Vol. 64, No. 4, pp. 23–26, 2013.

This paper presents the results of the study on the electrical tree growth of organo-montmorillon... more This paper presents the results of the study on the electrical tree growth of organo-montmorillonite (OMMT) nanofillers in silicone rubber under ac ramp voltage of 0.5 kV per second. This study investigates the ability of OMMT to retard the growth of electrical tree in silicone rubber. Samples of silicone rubber nanocomposites (two filled with 1% and 3% OMMT respectfully while the third is unfilled silicone rubber), were used in this experimental study and the growth rate of the electrical tree and its length were observed in both samples. .The result of this study has revealed that in the filled nanocomposite sample, the OMMT acts as barrier which slows down the growth rate of electrical tree. This makes OMMT a potential material to use as fillers in polymeric insulations for the purpose of retarding electrical tree growth.

Jurnal Teknologi, Vol. 64, No. 4, pp. 103–107, 2013.

This paper discusses the effects of nanofiller on electrical treeing growth in polymer nanocompo... more This paper discusses the effects of nanofiller on electrical treeing growth in polymer nanocomposites. The polymer nanocomposite consists of epoxy resin as the base polymer and organo-montmorillonite as the nanofiller. The influence of this nanofiller on the electrical treeing breakdown resistance was investigated experimentally. The quantity of organo-montmorillonite were added in epoxy resin by ultrasonication method based on weight percentage (wt%). The weight percentages used in this experiment were 0 wt% and 1 wt%, respectively. All the samples were produced in the form of leaf-like specimens which were categorized into two parts: unfilled sample (0 wt%) and filled sample (1 wt%). Point-to-plane samples were subjected to 0.5 kVrms/s HVAC ramp voltage. The data of tree inception voltage and tree breakdown voltage were collected and comparative results were made and presented. The morphological analysis of epoxy nanocomposites were investigated using field emission scanning electron microscopy (FESEM). Electrical tree parameters analysis has shown that the existence of organo-montmorillonite in epoxy resin could exhibit significant improvement of tree characteristics of epoxy resin nanocomposites as the nanofiller contributed to the increase of tree inception voltage and tree breakdown voltage.

IEEE International Conference on Power and Energy (PECON2012), 2-5 December, Kota Kinabalu, Malaysia, pp. 712-715, 2012

"This paper presents the results of the study on the performance of organo­montmorill... more "This paper presents the results of the study on the performance of organo­montmorillonite (OMMT) nanofillers in silicone rubber under high voltage application focusing on the ability of the OMMT to retard the growth of electrical tree in silicone rubber. Treeing experiments were conducted at a ramp ac voltage of 0.5 kV per second on unfilled silicone rubber samples as well as filled silicone rubber nanocomposites with 1 % weight percentage of OMMT. Tree inception voltage as well as tree length were observed on the filled and unfilled samples. In addition the morphological characteristics of the samples were investigated using Field Emission Scanning Electron Microscopy (FESEM) .
The result of this study revealed that OMMT inhibited electrical tree growth thus suggesting OMMT can be a potential material for use as filler in polymeric insulation for tree growth retardation. "

Annual Report of Conference on Electrical Insulation and Dielectric Phenomena (CEIDP2012) Montreal, Canada, October 14-17, 2012, pp. 898-901.

Electrical treeing is one of the main reasons for failure of polymeric materials used in high vol... more Electrical treeing is one of the main reasons for failure of polymeric materials used in high voltage applications. Treeing is observed to originate at points where impurities, voids, defects, or conducting projections cause excessive local electric field stress in the dielectric. It has been proposed that nanofillers could be employed as an electrical tree inhibitor in polymeric insulating materials. With development of nanotechnology, polymer nanocomposites have drawn much attention, because they are expected to have improved mechanical, thermal and electrical properties over the neat polymer. In this paper, modified nanoclay was used to examine the initiation and propagation of electrical treeing. Effects of electrical treeing on nanocomposites insulating material filled with 1 wt% and 3 wt% of Organo-Montmorillonite (OMMT) were used in this work. The results have shown that electrical tree growth was suppressed in silicone rubber nanocomposites compared with neat silicone rubber which allowed a faster growth of electrical treeing. However, more studies should be carried out with different nanofiller/silicone ratios to see in further enhancements in tree inhibition could be achieved.

International Journal of Electronics and Electrical Engineering , Vol. 6, 2012, pp. 213-218

""""The use of synthetic retardants in polymeric insulated cables is not uncommon in the high vo... more """"The use of synthetic retardants in polymeric insulated
cables is not uncommon in the high voltage engineering to study
electrical treeing phenomenon. However few studies on organic
materials for the same investigation have been carried. .This paper
describes the study on the effects of Oil Palm Empty Fruit Bunch
(OPEFB) microfiller on the tree initiation and propagation in silicone rubber with different weight percentages (wt %) of filler to insulation bulk material. The weight percentages used were 0 wt % and 1 wt % respectively. It was found that the OPEFB retards the propagation of the electrical treeing development. For tree inception study, the addition of 1(wt %) OPEFB has increase the tree inception voltage of silicone rubber. So, OPEFB is a potential retardant to the initiation and growth of electrical treeing occurring in polymeric materials for high voltage application. However more studies on the effects of physical and electrical properties of OPEFB as a tree retardant material are required. """"