A Study Of Moisture Effects On The Breakdown Voltage And Spectral Characteristics Of Mineral And Palm Oil-Based Insulation Oils

Based on a theoretical perspective,the primary function of insulation oils is to dissipate heat,and it serves as an insulator in between turn-to-turn windings in power transformers.To date,the majority of power transformer failures is attributed to the physicochemical reaction that takes place in the insulation oils due to the presence of heat,moisture content,oxidation and electrical stresses. Knowing that moisture content is one of the factors that leads to the degradation of transformer insulation oils,the main objective of this study is to examine the effects of moisture content on the breakdown voltage and Fourier transform infrared spectral characteristics of transformer insulation oils.Two types of insulation oils are chosen for this study:(1) conventional mineral-based insulation oil and (2)palm oil-based insulation oil which is a relatively new substitute for mineral-based insulation oils in Malaysia.The effects of moisture content is investigated by varying the amount of distilled water added into the oil samples from 1 to 5 ml, with an increment of 1 ml.Breakdown voltage test is conducted six times and the mean breakdown voltage is determined for each oil sample.The spectral characteristics of the oil samples are determined by means of Fourier transform infrared spectrometry.The breakdown voltage test and Fourier transform infrared spectrometry is carried out in accordance with the MS IEC 60156:2012 and ASTM D2144 standards,ensuring the reliability of the test procedures. Based on the findings of the study,it can be concluded that moisture content has a significant effect on the breakdown voltage and spectral characteristics of mineral and palm oil-based insulation oils – however,the effect is more pronounced for the mineral oil samples. Analysis of the Fourier transform infrared spectra reveals that the chemical composition of PFAE oil samples is not significantly influenced by moisture content and thus,this oil is a promising alternative for use as insulation oil in power transformers

Dielectric Strength Improvement Of Natural Ester Insulation Oil:Optimization Of Mixed Antioxidants Via Two-Level Factorial Design

Recent studies have shown that the addition of selected antioxidants into mineral oils or natural ester insulation (NEI) oils have improves the AC breakdown voltage (BdV), viscosity,flash point and fire point of these oils.The results of previous studies show that the addition of propyl gallate (PG) and citric acid (CA) antioxidants increases the AC BdV of NEI oils.However,previous researchers have implemented one-factor-at-a-time (OFAT) method as their experimental design approach and they overlooked the possibility through combination of antioxidants at optimum ratios that will yield a better result.In addition,a large number of test runs are required to investigate the effect of these antioxidant mixtures on the performance of insulation oils.Hence,in this study,two-level (2k) factorial design of experiments is used to determine the optimum concentration of PG and CA which will maximize the AC BdV of NEI oil.The results show that the optimum concentration of PG and CA that yields the highest AC BdV of NEI oils is 0.05 and 0.25 wt.%, respectively.A regression model is also developed to predict the AC BdV of NEI oils as a function of PG and CA concentrations

Comparative Study of Residential Lighting Technologies

As the lighting load constituted amount of power in electricity system, improving of efficiency in lighting technology would make a beneficial to consumer, energy provider and environment. Consequently, majority of home lighting manufacturers were competing each other by improving and claiming their product as the best energy efficient lighting product. Knowledge or exposure regarding to lighting technology especially on energy efficiency, power quality and economy are an important issues to give awareness to user before buy or use the lighting product. Therefore in this research study, three types of lighting product such as energy saving incandescent lighting, compact fluorescent lighting (CFL) and solid state lighting (LED) were compared. Comparative parameters were collected from data provided by lighting manufacturer and experimental data conducted in laboratory using power quality meter and lux meter. Hence, these study discussed in term of economy, power and light quality and energy efficiency of the tested lighting product. At the end of this study, the best home lighting technology is determined successfull

Comparative Study on the AC Brekadown Voltage of Palm Fatty Acid Ester Insulation Oils Mixed With Iron Oxide Nanoparticles

Mineral oils are are derived from petroleum which is a non-renewable and non-sustainable source, and therefore there is a critical need to develop alternative insulation oils for use in transformers.  Ester oils offer a number of benefits over mineral oils such as good biodegradability, high cooling stability, good oxidation stability and excellent insulation performance. Nowadays, nanotechnology has become one of the most important research fields in both the academia and industry and it has been shown in previous studies that nanoscale materials are beneficial for transformers. In this regard, the objective of this study is to compare the AC breakdown voltage of palm fatty acid ester (PFAE) oils mixed with iron oxide (Fe3O4) nanoparticles. The PFAE-based nanofluids are prepared using two methods: (1) Method I (weight-based method whereby the concentration of the Fe3O4 nanoparticles is 0.01 g/l) and (2) Method II (volume-fraction method whereby the concentration of the Fe3O4 nanoparticles is 0.01, 0.02 and 0.03%). The AC breakdown voltage test is conducted on the PFAE-based nanofluids in accordance with the ASTM D1816 standard test method. Weibull statistical analysis is carried out to analyse the AC breakdown voltage of fresh PFAE oil and PFAE-based nanofluids. It is found that there is enhancement of the AC breakdown voltage for all PFAE-based nanofluids with the exception of with the exception of one sample prepared using Method II (0.01% Fe3O4 nanoparticles)

A New Vector Draft Method for Harmonic Source Detection at Point of Common Coupling

In modern power networks, the issue of power quality (PQ) is becoming very important because of the increasing of load which sensitive to current disturbances. This is mainly due to the increasing use of non-linear power electronic devices draws nonsinusoidal current and creating a current distortion. As a result there is increasing need for PQ to be monitored to establish the type, sources and locations of PQ disturbances, allowing remedial measures to be taken. Consequently, harmonic is one of the most concerned power quality disturbances. The detection of harmonic source is necessary for power quality strategy development. This paper introduces a new single-point measurement method to estimate the harmonic source by using phase spectrogram (PS) and frequency spectrogram (FS) based on a vector draft method. A measurement at the point of common coupling (PCC) with harmonic distortion is done by simulation via PSCAD. Then PSCAD’s data are analyzed by using spectrogram in MATLAB. To be precise, voltage and current waveforms are normalized with fundamental magnitude respectively. Next, the normalized voltage and current are plotted on the vector draft to estimate the perpendicular point between the vectors. The center point of the normalized voltage is the boundary between downstream and upstream. The harmonic source can be detected base on the perpendicular point’s location that fall on the particular region. The comparison between actual and power direction result have been conducted. Finally, the proposed method is similar with the actual result and more truthful than power direction method

A new vector draft method for harmonic source detection at point of common coupling

In modern power networks, the issue of power quality (PQ) is becoming very important because of the increasing of load which sensitive to current disturbances. This is mainly due to the increasing use of non-linear power electronic devices draws nonsinusoidal current and creating a current distortion. As a result there is increasing need for PQ to be monitored to establish the type, sources and locations of PQ disturbances, allowing remedial measures to be taken. Consequently, harmonic is one of the most concerned power quality disturbances. The detection of harmonic source is necessary for power quality strategy development. This paper introduces a new single-point measurement method to estimate the harmonic source by using phase spectrogram (PS) and frequency spectrogram (FS) based on a vector draft method. A measurement at the point of common coupling (PCC) with harmonic distortion is done by simulation via PSCAD. Then PSCAD’s data are analyzed by using spectrogram in MATLAB. To be precise, voltage and current waveforms are normalized with fundamental magnitude respectively. Next, the normalized voltage and current are plotted on the vector draft to estimate the perpendicular point between the vectors. The center point of the normalized voltage is the boundary between downstream and upstream. The harmonic source can be detected base on the perpendicular point’s location that fall on the particular region. The comparison between actual and power direction result have been conducted. Finally, the proposed method is similar with the actual result and more truthful than power direction method

Determination of experimental domain factors of polyphenols, phenolic acids and flavonoids of lemon (Citrus limon) peel using two-level factorial design

This study aimed to evaluate the significant extraction factors in achieving higher recovery yield of total polyphenols, phenolic acids and flavonoids content from Citrus limon peel using two-level factorial design. The effect of five independent factors including drying temperature (40–60 °C), methanol concentration (20–60%), extraction temperature (28–60 °C), extraction time (30–60 min) and storage duration (0–14 days) were evaluated. Among all the examined factors, results showed that drying temperature, storage duration and extraction temperature were the most significant and contributing factors affecting the total polyphenols, phenolic acids and flavonoids content of lemon peel at P < 0.05. On the contrary, methanol concentration and extraction time exhibited the least significant and contribution at P greater than 0.05. In conclusion, the experimental domain factors were successfully obtained from this experiment, Therefore, further study on optimization of the obtained factors will be conducted in the future study using response surface methodology

MECHANICAL CONDITION ASSESSMENT OF TNB IN-SERVICE DISTRIBUTION TRANSFORMERS USING SWEEP FREQUENCY RESPONSE ANALYSIS (SFRA)

Distribution transformers in TNB (Tenaga Nasional Berhad) are exposed to the thermal and electrical stresses. Those stresses are effecting to the main mechanical active parts in transformer such as core and winding. In field, lightning strikes and cable faults may cause problem due to transformer core and winding. Sweep Frequency Response Analysis (SFRA) is an off-line diagnostic tool used for finding out any possible winding displacement or mechanical deterioration inside the transformer especially core and winding. SFRA diagnosis is made based on the comparison between two SFRA responses and any significant difference in low, middle and high frequency sub-bands region would potentially indicate mechanical or electrical problem to the winding and core of transformer. The aim of this paper is to assess the condition of TNB in-service distribution transformers by using SFRA method

Condition Monitoring of Distribution Transformer's Mechanical Parts Using Sweep Frequency Response Analysis (SFRA)

Distribution transformer is the key element in the electricity transmission throughout the nation. Hence, serious attention for the transformer condition monitoring is a crucial. With an occurrence of short-circuit in the power system, the transformer active parts such as core and winding will experience a mechanical movement created by the electromagnetic forces. There are various types of transformer condition monitoring measurement in market, but the monitoring of the mechanical movement in transformer is still lacking. Therefore, Sweep Frequency Response Analysis (SFRA) has been introduced to assess any mechanical movement especially of the transformer's core and winding. The frequency response of the transformer provides mechanical information of core and winding conditions. The SFRA measurement results were validated using the actual transformer untanking process

DIAGNOSIS OF OLTC USING DGA AND STATIC WINDING RESISTANCE TEST

On Load Tap Changer (OLTC) failure occurs is due to the insulation degradation and contacts failure inside it. Other than that, contacts wear influences the OLTC performances. The worn contacts will cause hotspots in the OLTC tank and cause the insulating oil to degrade faster. As a result, this will lead to the damage of complete transformer unit. Thus, the research work that has been carried out applied the Dissolved Gas Analysis (DGA) via latest Duval Triangle method during the diagnosis of OLTC rated at 33/11kV, 30MVA at the first stage to provide early indication of OLTC�s breakdown. The Static Winding Resistance Test is then applied at the second stage to figure out any increase of contact resistances for all phases. In addition, it is expected to have a relationship between both results. The results showed that it was proven that by performing DGA via latest Duval Triangle method, the early indication of OLTC�s breakdown can be obtained. Besides, this paper revealed that the Static Winding Resistance Test was capable to provide any sign of bad contacts in fixed condition as well as looses connections