Norhafiz bin Azis
@research.upm.edu.my
Electrical and Electronic Engineering
Advanced Lightning, Power and Energy Research Centre (ALPER)
RESEARCH, TEACHING, or OTHER INTERESTS
Energy Engineering and Power Technology, Renewable Energy, Sustainability and the Environment, Energy, General Energy
Scopus Publications
Scholar Citations
Scholar h-index
Scholar i10-index
Scopus Publications
Nurul Farahwahida Md Yasid, Norhafiz Azis, Jasronita Jasni, Mohd Fairouz Mohd Yousof, Mohd Aizam Talib, and Avinash Srikanta Murthy
Universiti Putra Malaysia
Switching operations in a power system network can lead to transient overvoltage in the high voltage (HV) winding of distribution transformers that causes high-stress build-up. This paper presents the relationship between electromagnetic force due to a standard switching impulse (SSI) and mechanical deformation/displacement behaviours for a disc-type transformer. The analysis was carried out based on a three-dimensional (3D) modelling of a continuous HV disc winding configuration whereby it is subjected to the switching transient voltage and force excitations through the finite element method (FEM). The electric transient solver analysed the static and dynamic aspects of the electromagnetic forces associated with the variation of forces versus time. The transient structural solver evaluated the structural behaviours of the disc winding related to the axial height and radial width of the winding under electromagnetic forces. It is found that the positively dominant axial force generated in the winding with a magnitude of 8.7 N causes the top and bottom layers of disc winding to tilt and displace. In addition, the positive average radial force of 1.4 N causes the circumference of the winding to experience hoop tension and outwardly stretch.
Najiyah Saleh, Norhafiz Azis, Jasronita Jasni, Mohd Zainal Abidin Ab Kadir, and Mohd Aizam Talib
Universiti Putra Malaysia
This study evaluates the Loss-of-Life (LOL) based on the modified relative aging rate of an Oil Natural Air Natural (ONAN) transformer with voltage and power ratings of 132/33 kV and 60 MVA. The study’s methodology included the determination of the Hotspot Temperature (HST) based on the differential equation in IEC 60076-7. The loading and ambient temperature profiles for HST determination are forecasted based on the Seasonal Autoregressive Integrated Moving Average (SARIMA). Next, a new relative aging rate was developed based on the Arrhenius equation, considering the pre-exponential factors governed by oxygen, moisture in paper, and acids at different content levels. The LOL was computed based on the new relative aging rate. The study’s main aim is to examine the impact of pre-exponential factors on the LOL based on modified Arrhenius and relative aging rate. The results indicate that the LOLs for different conditions increase as the oxygen, moisture, low molecular weight acid (LMA), and high molecular weight acid (HMA) increase. The LOLs are 46 days, 1,354 days, and 2,662 days in the presence of 12,000 ppm, 21,000 ppm, and 30,000 ppm of oxygen. In 1%, 3%, and 5% moisture, the LOLs are 477 days, 2,799 days, and 7,315 days. At 1% moisture, the LOL is 1,418 days for LMA, while for HMA, it is 122 days. The LMA has the highest impact on the LOL compared to other aging acceleration factors.
Nurul Husniyah Abas, Mohd Zainal Abidin Ab Kadir, Norhafiz Azis, Jasronita Jasni, and Nur Fadilah Ab Aziz
Institute of Advanced Engineering and Science
<div align="center"><span>This paper details a case study on the implementation of dynamic line rating (DLR) to enhance the ampacity rating of Malaysia’s grid. Utilizing heat balance equations endorsed by the Institute of Electrical and Electronics Engineering (IEEE 738) and the International Council on Large Electric Systems (CIGRE technical brochure 601), the ampacity rating of a Zebra-type aluminum cable steel reinforced (ACSR) conductor on a 275 kV transmission line has been assessed. Real-time weather conditions and conductor temperatures, measured hourly by the DLR sensor over the course of a year, were incorporated into the ampacity calculation to determine the available margin. The weather parameters were analyzed based on the monsoon seasons. A comparative analysis between various methods outlined in the standards and the estimated ampacity rating derived from both standards is presented. According to both standards, the findings indicate that DLR surpasses static line rating (SLR), highlighting the presence of untapped ampacity for grid optimization. Remarkably, CIGRE TB 601 exhibits a higher ampacity rating margin than the IEEE 738 standard, with a percentage difference of 16.20%. The study concludes that the conductor is underutilized and proposes optimization through the integration of real-time weather conditions data into the heat balance equations.</span></div>
Ziwei Ma, Jasronita Jasni, Mohd Zainal Abidin Ab Kadir, and Norhafiz Azis
Elsevier BV
R. Khan, M. F. M. Yousof, R. Abd-Rahman, S. M. Al-Ameri, and N. Azis
IEEE
Electrical machine condition monitoring is essential in industrial processes for increasing workplace security, ensuring reliability, and cost-effective machine operation. The frequency response analysis (FRA) monitoring technique is gaining heightened popularity due to its reliability. The main purpose of this paper is to investigate the influence of the rotor on motor FRA signature. The frequency response is a highly sensitive technique. Therefore, any small defect in the motor condition will produce a unique frequency response which then can be analyzed and detected early. In this study, two motors are selected, and the corresponding frequency response is measured. To understand the impact of the rotor on the FRA signature two measurements are considered. FRA signature with and without rotor. The results obtained from both measurements are compared and analyzed. For a better understanding of the results, statistical indicators are used. The practical results are based on the measurements taken from the experimental setup.
Muhammad Muzamil Mustam, Norhafiz Azis, Jasronita Jasni, Rasmina Halis, Mohd Aizam Talib, Nur Aqilah Mohamad, and Zaini Yaakub
Institute of Advanced Engineering and Science
<span>This study examines the effect of low molecular weight acid (LMA), moisture and oxygen on the thermal ageing characteristics of refined, bleached, and deodorised palm oil (RBDPO). The paper moisture was varied between 0.5% and 3.5%. The oil was initially subjected to 0.2 g of LMA and 20 mbar of oxygen pressure. The thermal ageing experiment was performed at 120 °C and 140 °C for 28 days. Several dielectric and physiochemical parameters were measured which included dielectric dissipation factor, relative permittivity, resistivity, moisture in oil, acidity, and thermogravimetric analysis (TGA). It is found that LMA and moisture in paper do not affect the <span>relative permittivity of RBDPO and mineral oil (MO). The dielectric dissipation factor of RBDPO and MO reveals slight increment trends within the ageing time. The decrements of resistivities occur after 7 days of ageing</span> <span>for both RBDPO and MO while only RBDPO shows decrement trend of moisture in oil. The ageing patterns of relative permittivities, dielectric dissipation factors and resistivities for RBDPO are similar to MO. The</span> <span>increment of acidity for RBDPO is more apparent that MO throughout the ageing time. All RBDPOs are more resistant to ageing than MO based on the TGA.</span></span>
Nurul Husniyah Abas, Mohd Zainal Abidin Ab Kadir, Norhafiz Azis, Jasronita Jasni, Nur Fadilah Ab Aziz, and Zmnako Mohammed Khurshid
Institute of Electrical and Electronics Engineers (IEEE)
As the world is pledged towards net zero carbon by 2050, the need for clean and efficient energy transitions is more critical than ever. Optimizing the power grid transfer capacity is crucial for maintaining grid stability and reliability. Ageing infrastructure, population growth, and revolutionary technological developments increase the demand for grid modernization and resilience investments. Climate change and natural disasters highlight the need for adaptive load-shedding schemes. The two possible ways to optimize the grid are an ampacity increase or a voltage increase. While increasing voltage provides the most significant rise in rating, it comes with high investment costs. Out of all the options available, dynamic line rating (DLR) is the most efficient and cost-effective solution. This paper provides a comprehensive review of the optimization of the grid transfer capacity using DLR. The review critically examines different line rating methods, the DLR system, factors that need to be considered before DLR implementation, and its advantages and disadvantages. Also, the review presents the real-world applications and case studies, standards and regulations involved, and current approaches and challenges for implementing DLR in Malaysia. Additionally, we highlight the most commonly used standards to calculate the conductor’s ampacity for the steady-state and dynamic state. Moreover, this review work presents how DLR can advance the grid’s flexibility, considering its significance for cleaner energy production in the future, challenges related to wind energy power generation, and their mitigations. This work provides a shortcut path for researchers and utilities to understand DLR and as a reference for future research to advance clean energy in response to changing energy needs and climate conditions.
Xinzhi Liu, Suhaidi Shafie, Mohd Amran Mohd Radzi, Norhafiz Azis, and Abdul Hafiz Abdul Karim
Elsevier BV
Muhammad Hakirin Roslan, Norhafiz Azis, Mohd Zainal Abidin Ab Kadir, Jasronita Jasni, and Mohd Fairouz Mohd Yousof
Universiti Putra Malaysia
This paper examines the influence of cavity size and location in the insulation paper on the Partial Discharge (PD) activities through Finite Element Method (FEM). The model consisted of a conductor wrapped with insulation paper. Two different locations of the spherical cavities were introduced in this study, namely Location 1 (L1) and Location 2 (L2), located at the center and left corner of the insulation paper. The model introduced two different sizes of cavities with diameters of 0.5 mm and 0.8 mm. An AC voltage source of 17 kV, 50 Hz, was applied at the conductor while the bottom of the insulation paper was grounded. The real and apparent PDs were obtained by integrating the current flowing through the cavity and ground electrode with the respective surface area. The simulation was carried out for 100 cycles. The resultant model was used to study the PD occurrence, magnitude, and Phase Resolved Partial Discharge (PRPD) within the insulation paper. It is found that the large cavity size produces a lower number of PD occurrences per cycle than the small cavity size. The large cavity size produces a higher charge magnitude as compared with the small cavity size. The PD occurrence per cycle and charge magnitude are higher for the cavity location at L1 compared to L2. The PRPD yields the same pattern for cavity location at L1 and L2, whereby the differences are only on the charge magnitude and PD occurrence per cycle.
Muhammad Muzamil Mustam, Norhafiz Azis, Jasronita Jasni, Rasmina Halis, Mohd Aizam Talib, Robiah Yunus, Nurliyana Abdul Raof, and Zaini Yaakub
Universiti Putra Malaysia
This study presents the short-term ageing study on refined, bleached and deodorised palm oil (RBDPO) and mineral oil (MO) in the presence of insulation paper, moisture, low molecular weight acid (LMA) and oxygen. The ageing experiment was performed for 7 days at 140°C. The oil was maintained dried while the paper’s moisture was varied between 0.5% and 3.5%. In total, 0.2 g of LMA and 20 mbar of oxygen pressure were initially introduced in the oil before the ageing started. Several analyses were conducted after the ageing experiment, which include the AC breakdown voltage (BDV) oil/paper, tensile strength, degree of polymerization (DP) and thermogravimetric analysis and differential scanning calorimetry (TGA-DSC). After being subjected to ageing in the presence of LMA and oxygen, the reduction of AC BDV of RBDPO is lower than MO at all moisture levels. At the same condition, the AC BDV of RBDPO-impregnated paper also maintains higher than MO-impregnated paper. The RBDPO-impregnated paper, in the presence of LMA and oxygen, has higher resistance toward ageing than MO-impregnated paper based on DP and tensile index, even in high moisture. All RBDPO are more resistant to ageing than MO in the presence of LMA and oxygen based on the high onset temperatures of the TGA-DSC analysis.
Emran Jawad Kadim, Zulkarnain Ahmad Noorden, Zuraimy Adzis, and Norhafiz Azis
Institute of Electrical and Electronics Engineers (IEEE)
Mineral oil has been used as a dielectric medium in transformers for more than a century. The enhancement of its performance using nanoparticles (NPs) has been investigated by many researchers in the last two decades. Based on that, in this article, NPs were introduced to improve the electrical and thermal properties of mineral oil. This article presents a model based on the use of COMSOL Multiphysics to evaluate the streamer current density, net space charge, and oil temperature. In this model, the electrostatics module, the stabilized convection–diffusion equation module, and the coefficient form of partial differential equations (PDEs) were combined. The results include the effects of different parameters of NPs: the size, time constant, and mobility of NPs. These results reflected the importance of the NPs’ time constant and how the NP’s mobility can influence the electrical and thermal characteristics of the oil. However, the results revealed that the volume of NPs had negligible effects on oil performance.
Ahmad Hafiz Mohd Hashim, Norhafiz Azis, Jasronita Jasni, Mohd Amran Mohd Radzi, Masahiro Kozako, Mohamad Kamarol Mohd Jamil, and Zaini Yaakub
IAES Indonesia Section
Emran Jawad Kadim, Zulkarnain Ahmad Noorden, Zuraimy Adzis, Norhafiz Azis, and Nur Aqilah Mohamad
Institute of Electrical and Electronics Engineers (IEEE)
Introducing nanoparticles to enhance the performance of mineral transformer oil has been considered in many studies recently. Typically, researchers focused on the use of widespread types of nanoparticles such as aluminum oxide, silicon dioxide, and titanium dioxide. However, there is no consensus on which type or concentration is suitable for this application. In this article, we studied different types of nanoparticles to investigate their effects on the electrical performance of mineral transformer oil with and without the use of surfactants. Design-of-experiments (DOE) approach was adopted to systematically produce oil-based nanoparticles, referred to as nanofluids, under different concentrations of nanoparticles and surfactants. With three concentration levels of three nanoparticles, namely, zinc iron oxide (ZnFe2O4), titanium carbide (TiC), and molybdenum dioxide (MoO3), the nanofluids were produced with three types of surfactants, which were oleic acid (OA), cetyl trimethyl ammonium bromide (CTAB), and polyvinyl alcohol (PA) under three different concentrations. Fifty successive ac breakdown voltage (BDV) tests were carried out for each sample using mushroom–mushroom cell according to IEC 60156. The results showed the dominance of TiC for two samples with and without surfactants. In addition, the DOE results showed the importance of concentration of nanoparticles and their types to enhance mineral oil’s performance.
Ziwei Ma, Jasronita Jasni, Mohd Zainal Abidin Ab Kadir, and Norhafiz Azis
Universiti Putra Malaysia
Researchers have worked on positive leader propagation models and proposed different theoretical and numerical approaches. The charge simulation method (CSM) has traditionally been chosen to model the quasi-static electric field of each stage of leader propagation. The biggest drawback of the CSM is that the calculation is complicated and time-consuming when dealing with asymmetric electric field structures. On the contrary, the finite element method (FEM) is more suitable and reliable for solving electrostatic field problems with asymmetric and complex boundary conditions, avoiding the difficulties of virtual charge configuration and electric field calculation under complex boundary conditions. This paper modeled a self-consistent streamer-leader propagation model in an inverted rod-plane air gap based on FEM and the voltage distortion method (VDM). The voltage distortion coefficient was analyzed to calculate the streamer length and space charge. The physical dynamic process of the discharge was simulated with the help of COMSOL Multiphysics and MATLAB co-simulation technology. The results show that the initial voltage of the first corona is -1036 kV, close to the experiment value of -1052 kV. The breakdown voltage of -1369 kV is highly consistent with the experimental value of -1365 kV. The largest streamer length is 2.72 m, slightly higher than the experimental value of 2.3 m. The leader velocity is 2.43×104 m/s, close to the experiment value of 2.2×104 m/s. This model has simple calculations and can be used in complex electrode configurations and arbitrary boundary conditions without simplifying the model structure, making the model more flexible.
Chi Zhang, Jasronita Jasni, Mohd Amran Mohd Radzi, Norhafiz Azis, and Xiangming He
Springer Science and Business Media LLC
Ahmad Hafiz Mohd Hashim, Norhafiz Azis, Jasronita Jasni, Mohd Amran Mohd Radzi, Masahiro Kozako, Mohamad Kamarol Mohd Jamil, and Zaini Yaakub
Institute of Electrical and Electronics Engineers (IEEE)
This article presents an examination on the acoustic partial discharge (PD) localization in oil based on adaptive neuro-fuzzy inference system (ANFIS) and artificial neural network (ANN) approaches. Impedance matching circuit (IMC) was used to measure the electrical PD. The acoustic PD was obtained through an acoustic emission (AE) sensor and preamplifier gain unit. In total, 112 coordinates for each of the AE sensors were utilized to evaluate the location of the PD. Once the voltage reached 30 kV, the electrical and acoustic PDs were recorded. Next, the data were preprocessed by moving average (MA) and analyzed by time of arrival (TOA), ANFIS, and ANN. The distance between PD and AE sensor was calculated based on TOA to determine the PD location. These information were used as an input to train the network by optimizing epoch and neuron for ANFIS and ANN in order to locate PD. ANFIS has the best percentage of PD source prediction based on root mean square error (RMSE) and coefficient of determination ( ${R}^{{2}}{)}$ as compared to ANN. Meanwhile, the computation time for ANN is 1.75 s faster than ANFIS to perform PD localization based on AE PD signals.
Nurul Farahwahida Md Yasid, Norhafiz Azis, Mohd Fairouz Mohd Yousof, Jasronita Jasni, Mohd Aizam Talib, and Avinash Srikanta Murthy
Institute of Advanced Engineering and Science
This manuscript discusses the computation of electromagnetic forces on a disc-type winding due to a standard switching impulse (SSI). First, the resistances, inductances and capacitances (RLC) of a 30 MVA, 33/11 kV disc-type distribution transformer were estimated to obtain the winding equivalent circuit. The transient voltage waveforms for each of the disc layers and corresponding resonances of the windings under the SSI were then obtained in time domains. Next, the axial and radial force distributions in the disc winding due to the SSI were computed. The forces on each disc layer and along the disc windings due to the SSI were computed based on the analytical and numerical methods via the finite element method (FEM) respectively. The non-uniform switching impulse voltage distribution results in non-uniform force distribution along the disc winding. The magnitude of the axially directed force on the disc winding is found to be higher as compared to the radially directed force.
Muhammad Hakirin Roslan, Norhafiz Azis, Mohd Zainal Abidin Ab Kadir, Jasronita Jasni, and Mohd Fairouz Mohd Yousof
Universiti Putra Malaysia
This paper investigates the behaviour of partial discharge (PD) in transformer insulation paper based on the Finite Element Method (FEM). The three-dimensional (3D) FEM model consists of conductor and insulation paper, representing part of a transformer’s high voltage winding. The conductor’s width, height, and length used in this study were 2.4 mm, 11.5 mm, and 16 mm. An insulation paper thickness of 1 mm was modelled around the conductor. An internal cavity with a diameter of 0.5 mm cavity was introduced within the insulation paper. This study introduced two locations of the spherical cavities at the centre and left corner of the insulation paper: Location 1 (L1) and Location 2 (L2). An AC voltage of 33 kV, 50 Hz, was applied to the conductor while the bottom of the insulation paper was grounded. The model was used to study the electric field distribution within the insulation paper and its effect on PD current and charge magnitude. The influence of cavity location on the charge magnitude was also examined. It is found that the electric field distribution is influenced by the conductor configuration as well as the location of the cavity. The electric field in the cavity is the highest at L1 compared to L2. The first PD occurs faster for the cavity with a high electric field. Due to the PD occurrence at the same inception field, the real PD current and charge magnitude is similar at different locations. The apparent PD current and charge magnitude induced at the ground electrode is slightly higher at L1 than at L2.
Muhammad Umair, Norhafiz Azis, Rasmina Halis, and Jasronita Jasni
Universiti Putra Malaysia
This work examines the physical and electrical breakdown characteristics of kenaf paper coated with Polyvinyl Alcohol (PVA) for application in power transformers. The paper was made from kenaf bast fibers using the soda pulping method, whereby the pulps were subjected to 12,000 beating revolutions. PVA with weight percentage concentration up to 6% was introduced to the beaten kenaf through a spin coating approach. The structure of the kenaf paper was examined through Scanning Electron Microscopy (SEM). The physical properties examined were apparent density, Tensile Index (TI), Burst Index (BI), and Tear Index (TeI), while AC breakdown voltage and strength were analyzed for the electrical property. It is found that the beating and external PVA improve the kenaf paper’s apparent density, TI, BI, and AC breakdown strength while the TeI decreases.
Chi Zhang, Binyue Xu, Jasronita Jasni, Mohd Amran Mohd Radzi, Norhafiz Azis, and Qi Zhang
MDPI AG
Faced with the increasingly serious energy crisis and environmental pollution problems, traditional internal combustion engine vehicles are receiving more and more resistance, which has rapidly promoted the development of new energy electric vehicles. Permanent magnet synchronous motors are widely used in new energy electric vehicles and in other fields because of their simple structure, light weight, small size, and high power density. With the continuous advancement of production technology, the requirements of accuracy, rapidity, and stability in permanent magnet synchronous motor systems have gradually increased. Among many advanced control technologies, this paper proposes an optimized model predictive torque control strategy based on voltage vector expansion. This strategy involves the construction of a reference stator flux linkage vector based on the analytical relationship between electromagnetic torque, reference stator flux linkage amplitude, and rotor flux linkage and the transfer of the separate control of electromagnetic torque and flux linkage amplitude into flux linkage vector control. At the same time, the optimal duty cycle corresponding to the two adjacent extended voltage vectors and the zero vector is calculated according to geometric relationships so as to realize the three voltage vector duty cycle optimization control. Experimental results show the effectiveness and superiority of the proposed strategy.
Chi Zhang, Jasronita Jasni, Mohd Amran Mohd Radzi, Norhafiz Azis, and Xiangming He
Frontiers Media SA
Sustainable development in the 21st century faces significant challenges due to finite reserves of fossil fuels and environmental pollution. In the context of new energy electric vehicles (NEEVs), the wide-bandgap semiconductor known as the silicon carbide–metal oxide–semiconductor field-effect transistor (SiC MOSFET) and the permanent magnet synchronous motor (PMSM) have emerged as advantageous sources. However, the use of these components gives rise to electromagnetic interference (EMI) issues, which impede the achievement of electromagnetic compatibility (EMC) standards in the motor drive control system. This paper aims to elucidate the generation mechanism, propagation path, and test infrastructure of EMI. Furthermore, it proposes a system-level conducted EMI equivalent circuit model for the motor drive control system, encompassing the power battery pack, busbar cable, LISN, three-phase inverter, and PMSM. Building upon this foundation, the principles for suppressing and optimizing EMI noise are discussed. The paper concludes with the validation of simulations and experimental results, which demonstrate the effectiveness of the proposed approach. It is anticipated that professionals with an interest in the field of EMI/EMC will find this paper to be of both theoretical and practical importance.
N. A. Othman, H. Zainuddin, M. S. Yahaya, N. Azis, Z. Ibrahim, and M. A. C. Musni
IEEE
Retrofilling of an existing mineral oil-immersed transformer with ester oil is an alternative approach to extend the lifespan of transformers. This is associated with the excellent properties of ester oil that has high tolerance to moisture that promotes an advantage to prolong the life of paper insulation. However, the retrofilling process will mix the fresh ester oil with the remaining aged mineral oil in the transformer oil, and eventually affects the performance of the new ester oil. Therefore, it is essential to access the performance of mixed oil in order to detect any signs of oil degradation as a result of retrofilling, prior to transformer energization. In this paper, the total acid number (TAN) and Fourier Transform Infrared (FTIR) spectra were measured and analyzed to assess the condition of mixed aged mineral-synthetic ester oil (AMO/SE). Three different proportions of aged mineral oil (AMO), i.e. 3 %, 5 % and 7 % were prepared to simulate different amount of mineral oil residue in a transformer before being retrofilled with fresh synthetic ester oil. The AMO were prepared through thermally ageing of fresh mineral oil in a vacuum oven at 130°C for 150 hours. Based on the findings, it has been intriguingly discovered that the acid number of the AMO/SE oil has decreased as the percentage of AMO increased in fresh synthetic ester oil. In correlation with FTIR spectra, the present acid concentration of the degradation by-product of the retrofilled AMO/SE oils can be observed in carbonyl stretch region at the wavelength of 1700 – 1800 cm$^{-1}$.
Siti Nur Aishah Binti Azman, N. H. Nik Ali, Atip Doolgindachbaporn, A. Mohd Ariffin, N. Azis, and N. Aminudin
IEEE
The International Electrotechnical Commission (IEC) has created standards for transformers, which are normally adhered to by the great majority of those that are used in locations all over the world. When it comes to calculating transformer ratings, Malaysia is one of the nations that use the International Electrotechnical Commission’s (IEC 60076-72018) for power transformers. Based on the equations in the standard, transformer rating can be affected by changes of the environmental conditions, e.g. ambient temperature. The recent climate change in Malaysia had an influence on the transformer rating that has been mentioned in the IEC standard. This situation is the impetus for conducting this research in the first place. The ambient temperature profile which is based on a few of the world continents’ profiles and also specifically the ambient temperature profile in Malaysia are studied and presented by varying ambient temperatures in the IEC Standard mathematical algorithm. The IEC 60076-7 offers recommendations for the specification and loading of power transformers with regard to operating temperature and thermal ageing. This work will focus on the hot spot and top oil temperature of a transformer. The result shows that by changing the ambient temperature by 10 degrees will give effect to the hot spot and top oil temperature and therefore, the ratings of the transformer will also be affected.
Nur Darina Ahmad, Ahmad Hafiz Mohd Hashim, Norhafiz Azis, Mohd Aizam Talib, Khairil Anas Md Rezali, N. H. Nik Ali, Jasronita Jasni, Kozako Masahiro, and Mohamad Kamarol Mohd Jamil
IEEE
This paper examines the performance of partial discharge localization refined bleach deodorized palm oil (RBDPO) based on acoustic emission (AE) partial discharge (PD) method. The PD was initiated through a needle-plane electrodes configuration. The electrical PD was measured through Impedance Matching Circuit (IMC) whereby the AE PD signal was measured using AE sensor placed on the surface of the test tank. The time of arrival (TOA) was computed based on the electrical and AE PD signals. It is found that the PD count and maximum amplitude for RBDPO are lower than mineral oil. The PD in RBDPO can be located through TOA whereby the location error is lower than MO.