Hana Abdull Halim
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Preferred name
Hana Abdull Halim
Official Name
Abdull Halim, Hana
Alternative Name
Halim, H. Abdull
Abdull Halim, H.
Halim, Hana Abdull
Halim, H. A.
Halim, Hana A
Main Affiliation
Scopus Author ID
57189503727
Researcher ID
W-7258-2019

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Varying the energisation condition to mitigate sympathetic inrush current

2023-12-01 , Nadhirah N.F. , Hana Abdull Halim , Nurhakimah Mohd Mukhtar , Samila Mat Zali

Transformers are generally easy to access and can contribute significantly to entire power system. When a transformer is turned on for the first time, it produces a magnetising inrush current which acts as a starting current. Energisation of transformer has a substantial impact on inrush current and transformer that are connected in parallel. Sympathetic inrush current is a phenomenon that appears when a transformer is switched-on in network whereas the other transformers that was earlier energised. Besides, when sympathetic inrush phenomena occur, the peak and period fluctuate significantly. In this paper, the transformers will be energised in three different ways and each condition will be explored in depth. The operation time of the transformer’s energisation whether it is energised simultaneously or at different times are tested and analysed in terms of their characteristics. It is performed using power system computer aided design (PSCAD) software, starting with a develop model of the energisation and then generate the outcomes. The results of the simulation demonstrate that energising the transformer in different ways can give different effect on the sympathetic inrush current, as well as the variables that affect it and methods for reducing it

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Assessment and mitigation studies of voltage sags during sympathetic inrush current

2025-04 , Hana Abdull Halim , Haziah Abdul Hamid , Nurul Fatin Nadhirah Subli

The system voltage may be negatively impacted by the transformer’s energisation which draws a large value of magnetising inrush current for a few seconds. During the transformer’s energisation process, it experiences an unexpected saturation. When the transformer is saturated, the growth of magnetising inrush current, sympathetic inrush current and voltage sags are a few issues that are appear. Numerous variables that affect the inrush current and the resulting voltage sags were taken into consideration. This is due to the fact that the energisation of a large power transformer may result in a high voltage sag which relies on a value of parameters, including the duration of the circuit breaker closing time. One of the most essential objectives for power quality is the research of voltage sags that appear in a network. The goal of this project is to investigate sympathetic and inrush currents as well as to assess the voltage sag that occurs during transformer energisation and how severe it is. In this paper, the voltage sags are analysed by modelling 100kVA, 11kV/415V of wye-delta of single line (circles) transformer and using PSCAD software. It is expected to observe the magnitude, the duration and the percentage of voltage sags in order to make a comparison result between single connected transformer, two parallel-connected transformers and three parallel-connected transformers. To predict the severity of the sympathetic inrush current, the effects of voltage sags and their assessment is developed. As a result, it has been shown that the more energisation of the transformers, the peak of inrush current increases causing the higher magnitude and the longer duration of voltage sags. In conclusion, the voltage sags also become severe and persists for a longer duration when the number of transformers in operation are increased.

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Profiling crowdsourcing practices trend among SMEs in Malaysia

2021-07-21 , Mansor M.F. , Hana Abdull Halim , Ahmad N.H. , Abu N.H. , Kassim M.A.M.

Small and Medium Enterprises (SMEs) are the important 'engines of growth' for developed and developing countries. They are the main share of total enterprises and contributes significantly to the Gross Domestic Product (GDP), employment and export. Nevertheless, SMEs remain unachieved the expected success due to grapple with the failure risk, survival downturns and uncertainty environment. To overcome these challenges, the SMEs have to explore the best business strategies i.e crowdsourcing practices for their organisation to boost business performance. Therefore, the objective of this study is to investigate and profiling crowdsourcing practices among Malaysian SME's that possibly could be one of the organisational business strategies to complement resources scarcity and improve business performance. This study also exploring the crowdsourcing practices scenario in Malaysia, crowdsourcing business activities, crowdsourcing platforms and its effect towards business performance. The study employs quantitative approach. The findings revealed that, the crowdsourcing trends showed that SMEs not only crowdsource non-core business activities but they also tend to crowdsource some of core business or complex business activities such as new product development, marketing research and innovation activities to increase organisational capability to overcome internal resources constrains. The study also highlights both practical, theoretical implications, limitation and future study.

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Experimental Investigation on Thermal Conductivity of Palm Oil and Zinc Oxide PFAE-based Nanofluids

2023-01-01 , Azizie N.A. , Nuriziani Hussin , Hana Abdull Halim , Muhammad Irwanto Misrun

Vegetable oil (VO) have been constantly researched as an alternative to the conventional mineral oil (MO) in the application of transformer insulation liquid. VO is deemed as a suitable replacement for MO as they are a renewable source, cheaper in price, and have a high thermal conductivity, high flashpoint, and high breakdown voltage value. In addition, the trending interest in nanofluids has made it possible to further improved the insulating properties of VOs. This paper reports the experimental results of thermal conductivity test of Palm oil-based nanofluids and Palm fatty acid ester (PFAE)-based nanofluids. The nanoparticles used in this work is Zinc Oxide (ZnO) <50nm nano powder and the nanofluid (NF) samples are varied by low, medium and high concentrations. The test was conducted at 9 different temperatures from 25°C to 65°C with 5°C gap. The result shows that a low and medium concentration nanofluid has an improvement in thermal conductivity value, up to 42.6% and 59.5% respectively for palm oil-based nanofluid. Meanwhile, the high concentration palm oil-based nanofluid has lower enhancement in thermal conductivity value at certain temperatures. As for PFAE-based nanofluids, the thermal conductivity value has improved by up to 27% and 14.4% for medium and high concentration respectively. Nanofluids with medium concentration of ZnO, has the highest enhancement in insulating and cooling properties for both palm oil and PFAE-based nanofluids. This observation is supported by the kinematic viscosity value of the mentioned nanofluid.

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Effect of load capacitance on sympathetic inrush current

2023-12 , Nurul Fatin Nadhirah , Hana Abdull Halim

In electrical systems, transformers are used to step up or step down the voltage to meet the needs of different loads. When a transformer is energised for the first times, it draws a high current or also known as inrush current. The inrush current can cause a several issues such as voltage dips, mal-operation and other in the electrical network. Besides, when the sympathetic phenomena are occurred, the magnitude and duration of the current changed dramatically. One of the factors that can affect the magnitude and duration of inrush current is the presence of load capacitance. This study uses a simulation model to investigate the impact of load capacitance on sympathetic inrush current that drawn by two-parallel connected transformers under different circuit breaker operating times. The goals of this project to investigate the effect of load capacitance on sympathetic inrush current as well as by varying the value of load capacitance to observe how severe it is. In this paper, the effect of load capacitances is analysed by modelling 100 kVA, 11 kV/415 V of wye-delta of single line (circles) transformer and all the schematics model and simulation results are performed by PSCAD software. As a result, it is expected to observe the magnitude and duration of sympathetic inrush current to make a comparison within ten different values. According to simulation results, the higher value of load capacitance can produce the lower magnitude of sympathetic inrush current as well as shorten the duration of the current appear which is the time taken to reach steady state. The findings of this study can aid in the design of the transformers to minimize the impact of sympathetic inrush current. In conclusion, this project contributes to new research contribution and expected to be completed within the given time frame.

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Arcing fault diagnosis using first peak arrival of EM radiation signal

2021-06-11 , Melaty binti Amirruddin , Mohd Rafi Adzman , Nur Adyani Mohd Affendi , Azralmukmin Azmi , Muhd Hafizi Idris , Hana Abdull Halim , Muzamir Isa , Halim S.A.

The objective of this study was to diagnose the arcing fault signals based on the first peak of arrival method using antenna to assess its use as potential arcing fault detection in power system network. Square patch antenna and circle patch antenna were employed for detection on artificial arcing in real environment. First peak of arcing signal arrival was measured through an analysis over a range of time and amplitude signals detected. For accurate results, Discrete Wavelet Transform (DWT) denoising technique was applied to the arcing signals detected as denoising tools. Analysis of first peak of signal arrival time and amplitude were carried out using MATLAB software to measure the changes in signals detected caused by di different placements of antenna. The results revealed that the first peak of signal arrival time, amplitude, type of antenna used and placement of the antenna around arcing source point all reflect the signals measurement.

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