Life Remnant of Transformer by Measuring Oil Reflectiong
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Submitted By ppschk Words 7668 Pages 31
Abstract
Power transformers are one of the most important parts of the power system. Failure of a transformer affects power supply to citizen and affects the income of business sector. Condition monitoring of power transformer is very important. By measuring the furan contents in power transformer oil can give a sign of the power transformer health, using this method is more convenient and economical among all the methods. With the aid of UV-Vis Spectrometer, light absorption and transmission with various furan contents of different power transformers with different ages are measured and compared. The measured results are used to predict the furan contents and remnant life of the power transformer can estimate. Copper dusts added into transformer oil in order to investigate the effect on the light absorption and transmission. The measured results show the impact of copper dust on light absorption and transmission characteristics that can provide indication of transformers remaining health condition. This thesis presents the measurement of power transformers oil samples with different furan contents for remnant life estimation.
Key words: Power Transformer, Copper Dust, Transformer oil, UV-Vis Spectrometer, Furan, Health
Chapter 1
Introduction
1.1 Power Transformer
Figure 1: A basic power transformer.
Power Transformers are critical elements in an electrical power system. It is used to step-up or step-down voltage level as needed to serve the transmission or distribution networks. It is stepped up for transmission over long distances to avoid a huge power lost and stepped down for final use. Transformer is one of the most expensive assets in power transmission and distribution networks and millions of dollars are spent each year in operating, maintaining and repairing this equipment. The cost of acquisition, replacement, transportation, installation and repairs of power transformer is among the highest cost in the systems. Health of the transformer can be monitored to ensure the insulation and windings work well. In order to monitored it, cellulosic paper of the transformer have to be examined and if the results of the paper is it losses up to 75% of its tensile strength, it means it is the end of the transformer life or a major maintenance can be held. There is other method which is testing transformer oil, it will be cheaper than getting the insulation paper inside the transformer since it doesn’t require draining up most of the oil to get the insulation paper.
1.2 Main Objective
The main objective of this research is to improve the accuracy of results of relationship between furan concentration by and UV-Vis spectral response using absorption test and transmission test. In order to obtain a more accurate result, some metal powders are used to add into the oil sample which will affect the life of the transformer and the absorption of the oil sample. Examine the UV-Vis spectral response of oil under different samples, with or without metal powder, depending on the quantum of the furan content of the oil sample. At the completion of project, the method of testing life remnant of power transformer is more accurate with the previous lab research done by others people.
1.3 Research objectives * Investigate the relationship between furan contents and UV-Vis spectral response of light absorption and transmission test. * Investigate the relationship between furan content and UV-Vis spectral response of oil samples the copper dust (saturated and un-saturated condition). * Analyse and compare the measured results with each other. 1.4 Organisation of the Thesis
Total 7 Chapters and two Appendixes are included in this thesis. A brief description of the contents of every chapter is explained below:
Chapter 2 presents the literature review of the topics related to power transformer background which included the insulation, deterioration and failures factors and condition monitoring of transformer. Will also describes the insulations condition of the transformer. The aging health and the end of life assessments of the transformer will also be discussed in this chapter.
Chapter 3 presents the detail analysis of furan compounds in the transformer oil will be discussed in this chapter, and explanation of how it is related to the health, aging of the transformer. How it is tested out from the oil sample by using UV-Vis Spectral Response. (Some data from others researcher will be presented in here as well).
Chapter 4 provides the description of the experiment will be presented. Setting of the experiment and experiment instrument will be introduced, and how does the experiment works.
Chapter 5 presents the experimental results and the relationship between furan and UV wavelength with UV-Vis range spectral response analysis.
Chapter 6: Analysis of the results will be presented in this chapter which included using MATLAB to calculate the area of the graph, and discussion of the analysis will be held.
Chapter 7 presents the conclusion and recommendations for the future research. The thesis is concluded with the explanation of the significance of the work performed.
Chapter 2
Back Ground 2.1 Introduction
Figure 2.1: Three phase transformer coil (Building progress).
Small transformer that we usually use in laboratory or our electrical instrument can be self-cooled by air circulation, and large power transformers are usually immersed in transformer oil that helps to cool the winding and act as an insulator. The photo shown above is a large power transformer coil which will produce a large heat; it is needed to place in a tank and immersed in transformer oil in order to cool the winding, which was showed on the photo below.
Figure 2.2: Transformer coil immersed in oil.
Maintenance plans and condition monitoring techniques are some of the general asset management activities which can be applied to any equipment such as generator, circuit breaker, relay, etc. however, each management activity will be different according to their equipment. For example, monitoring power transformer is different from generator set which needs to monitor the output of voltage, current temperature, etc. These monitoring methods were developed by organizations and research institutes by which to investigate the condition of the device/instrument. And there are few methods to monitor a power transformer; they are classified into electrical and chemical analysis. They are some standard guideline of monitoring power transformer which is published by ASTM and IEC organizations. Their standards are updated time to time in order to obtain the most advancement technology. Researchers and engineers continuously searching, modifying and developing advance method for monitoring in order to obtain a more effective, accurate, economic way.
2.2 Deterioration and failure factors
The factors responsible for transformer failures and accelerated deterioration are stated as below:
2.3.1 Operating Environment (Electrical)
Operating Voltage (50/60Hz), Transient over-voltages, load current, short circuits (fault currents), lightening and switching surges.
2.3.2 Operating environment (Physical)
Temperature (operating full load with high ambient temperature-humidity index), wind, rain, seismic and pollution.
2.3.3 Operating time
Time in service and time under abnormal conditions or extreme condition which are load variation or change in thermal, etc.
2.3.4 Number of operations of tap changer
Number of on-load taps changer operation.
2.3.5 Vibration Effect
Sound and material fatigue.
2.3.6 Contaminants
Moisture (water content in oil), presence of oxygen and particles in oil, and furan content of the oil which the research of this thesis will be focusing in this part.
2.3 Condition Monitoring of Transformers
Condition transformer condition monitoring of the process of data collection and processing related to various parameters of the transformer in order to predict failure of the transformer, the transformer parameters by observing from their expected value, and to take preventive measures. Transmission and distribution transformer is the most important asset of the system, and may cause power outages, personal and environmental hazards and expensive re-routing or purchased from other suppliers of power if they fail. Transformer fault occurs due to various causes. Transformer service interruptions and failures are usually due to dielectric breakdown, winding deformation cause by short-circuit withstand, winding and magnetic hot spots, electromagnetic interference, insulation deterioration, lightning, lack of maintenance, loose connections, overload, fault-load and other accessories tap, casing, etc. integrated personal reasons monitor allows monitoring of the overall condition of the transformer. Transformer condition monitoring is an important aspect which will be discussed below.
Figure 2.4: Condition Monitoring of transformer Parameter.
2.4.7 Thermal Modeling
Dissipating heat generated within the transformer to its circumference part of the transformer’s ability to determine the useful life. Actual and projected operating temperature of comparison, we can provide a sensitive diagnostic transformer condition may indicate abnormal operation. The consequences of temperature rise may not be abrupt, but as long as gradually, as it is within the limits of resolution. These consequences are economically important deterioration of insulation. Insulation is very expensive, and its degradation is not desirable. Thermal modeling is to develop a mathematical model to predict the temperature distribution of the power transformer thermal analysis principle. Thermal model is used to determine the optimum oil temperature and the hot spot temperature (maximum temperature occurs in the winding insulation system).
2.4.8 Dissolved Gas Analysis (DGA)
Gases are produced during the degradation process of the transformer oil and solid insulating materials. Gasses will produce more rapidly while there is an electrical fault happens. The cause of fault gasses are assort into 3 categories which are corona or partial discharge, thermal heating and arcing. By evaluating the quantities of hydrocarbon gases, hydrogen and oxides of carbon that are present in the transformer can helps to detect these faults. Different gasses mean different types of faults. The concentration of the gasses helps to predict what sort of fault might occur.
2.4.9 Frequency response analysis (FRA)
When a transformer is subjected to high currents through fault currents, mechanical structure and windings are subjected to severe mechanical stresses causing winding movement and deformations. And it may cause the insulation damage and turn to turn faults. Frequency response analysis is a non-intrusive sensitive technique for detecting winding movement faults and deformation assessment caused by loss of clamping pressure or by short circuit forces. This method involves measuring the impedance of the windings of the transformer with LV since input varying in frequency range.
2.4.10 Partial discharge analysis
It occurs when a local electric field exceeds a value, result of a partial breakdown of the surrounding medium. Its cumulative effect leads to degradation of insulation. Partial discharge is initiated by the presence of defects during manufacture or the higher stress dictated.
2.4 Aging, Health, and End of Life Assessment
Aging of Equipment is a fact of life in power system components. While an equipment ages, it possibility of failing is higher and it needs more maintenance and repair time until it reaches its end of life. Anyhow, maintenance activities can help to extend the life of the equipment but it will become expensive for the equipment while it’s close to its end of life. Basically, there are 3 types of lifetime for power transformer which is as follows [3]:
2.5.11 Physical lifetime
Equipment from the start of its operating till it cannot be operated normally and got to be replaced.
2.5.12 Technological lifetime
Equipment may need to replaced due to technological reasons, even if it doesn’t not reached its physical life me, for example, a newer control system of a generator had been replaced the old control system in order to obtain a clearer monitoring system or the manufacturers doesn’t produce the old spare parts which need to be replaced.
2.5.13 Economic lifetime
While a piece of equipment is no longer economical valuable, although it can still be normally operate. But the capital value of the equipment is depreciating every year. And once the asset value reaches 0, it is the end of its economic lifetime.
Chapter 3
Furan in Transformer Oil
Furan is heterocyclic organic compounds, which consist of 5 membered aromatic rings with 4 carbon atoms and oxygen. Furan is colorless flammable, highly volatile liquid with a boiling point close to room temperature.
3.1 Relationship between furan contents and transformer health
Figure 3.1: Relationship between the blood circulation of human body and the transformer oil.
Figure 3.1: Relationship between the blood circulation of human body and the transformer oil.
As we can see from the figure above, the blood circulation and the circulation of the transformer oil are quite similar. Human can check their health by checking their glucose level and transformer can check their health by checking their furan content. If the furan level is too high it means that the health of the transformer is getting worse.
3.2 Furan Compound in Transformer
As a paper insulation ages, the polymer chains starts breaking and generating glucose monomer units that undergo further chemical reaction and become one of the family of derivatives of 2-furan, that increase in the transformer oil with the decrease of the DP of insulating paper. These furanic compounds dissolve in the transformer oil and can be detected by oil analysis.
There are mainly 5 kind of furanic compounds can be found in transformer oil with the current technology. Which are 2-furan (2-FAL), 2-Furfurol (2-FOL), 5-Hyroxy methyl-2-furfural (5-HMF), 5-Methyl-2- furfural (5-MEF), and 2-Acetylfuran (2-ACF)[4] lai sin ping
As shown in the figure below.
Figure 3.2: Furanic Compounds detectable in transformer oil [4].
Furans are produced from pyrolysis mechanism of levoglucosane and hydrolytic degradation of cellulose in the paper. Levoglucosane is the precursor of furanic compounds and it is a by-product from the cellulosic paper at temperatures higher than 130 degree Celsius due to degradation.
The amount of the furanic compounds corresponding to DP of 200units which modified in the formulas showed below which are related to DP and the amount of furanic compounds in ppb by weight.
DP = log10(total furans) − 4.0355 − 0.002908 (1)
This formula used the total furans in ppb by weight which can be used to calculate DP.
DP = log10(2FAL × 0.88) − 4.51 −0.0035 (2)
And the formula above shows the relationship between 2FAL and the DP for non-thermally upgraded paper which is used nowadays.
Figure 3.3: production of 5-HMF and 2-FAI from LG [4].
Furanic compounds analysis is becoming more and more popular which is giving a more economic and easier method to estimate the life of a transformer. However the furanic compounds might be affected by some other condition like humidity, operating area, operating temperature, type of oil and paper, type of insulating material, design of the coil, etc. And research on the transformer oil obtained substances which affect the UV-Spectrum.
Figure 3.4: Factors influencing the performance and degradation of transformer[5].
3.3 Furan analysis
All oil samples are prepared according to ASTM D 5837 standard and tested using GC/MS system for furan derivatives identification and quantification. Each sample was treated with acetonitrile prior to extract for test that was arranged to GC/MS.
According to (Lai. 2008) An Aged transformer oil and four samples of chosen in-service transformer oil with different furan concentration were tested in GC/MD and UV-Vis Spectrometry analysis. And the results were shown as the table above.
It can be seen that the laboratory aged transformer oil is insufficient to generate an amount for detection. Which other four samples of in-service transformer oil with high furan concentration collected from 150KVA power transformer age between 10-20 years. This table also shows that the main constituent of furan derivative is 2-fal which is the highest solubility in the oil and consistent with the possibility of using it as an oil degradation indicator in the diagnosis of transformer cellulosic insulation condition.
From the results Lai presented, we can have an obtained results of the correlation between 2-fal and DP value as shown below. 2-FAL (ppm) | DP Value | Status | 0-0.1 | 700-1200 | Healthy | 0.1-1.0 | 450-700 | Moderate | 1-10 | 250-450 | Bad | > 10 | < 250 | End of service |
Table 3.2: Correlation between 2-Fal and DP Value [5].
3.4 UV-Vis Spectral Response
UV-Spectrophotometry is a non-intrusive test used to determine the transformer’s integrity. UV-Spectrophotometry is an accurate and sensitive method to analyse impurities in the transformer oil using light absorbing properties of a sample. Light transmitted through the oil sample containing various contaminations are decreased by that fraction being absorbed and is detected as a function of wavelength. A spectrophotometer measures the transmission, absorption or reflection of the light spectrum for a given wavelength. Absorption spectroscopy provides a measure of how much light is absorbed by the oil sample which can use the following formula to calculate.
Aλ=-log(Sλ-DλRλ-Dλ) (3)
A: Absorbance
S: Sample Intensity at wavelength D: Dark intensity at wavelength R: Reference Intensity at wavelength Same oil samples used for furan concentration measurement using GC/MS were tested using a laboratory grade spectrophotometer for absorbance spectrophotometry at room temperature 20ºC. The experiment procedure was set up in reference to ASTM E275. Figure below shows the lab set up for measuring spectral response for one oil sample. Figure 3.5: Lab set up for measuring the spectral response of transformer oil.
As shown on the figure above, the light source will send the light through input fiber into the cuvette in the cuvette holder. And the light interact the sample, and then output fiber helps to carries the light from the oil sample to the spectrometer which is connected to the computer.
It can be shown from Figure 10 that the new oil exhibits its characteristics between 200 and 350nm uv-spectrum with maximum absorbance at 250nm wavelength. However, in-service and laboratory aged oil samples exhibit their respective characteristics in the range of 200 and 470nm wavelength uv-spectrum. Results show that absorbance as well as bandwidth for maximum absorbance increases by a significant and easily observable margin with oil deterioration and contaminations which are reflected by the furan concentration level in the oil. UV spectrum shows considerable noise for contaminated oil which can be attributed to the variety of contaminations
Figure 3.6:UV/Vis Spectrum (Absorbance) for different oil samples [6].
Chapter 4
Experimental Setup for Measurement
4.1 Purpose of this experiment
The purpose of this experiment is to examine the relationship between furan concentration and UV-Vis Spectral response using absorption and transmission. And compare the relationship of absorption and transmission of the results obtained from the experiment. In the meantime, metal copper will be added in some chosen oil sample to examine if it would affect the results obtained.
4.2 Theory
In order to obtain the relationship between furan concentration and UV-Vis Spectral, the following equations are needed to be used:
For absorbance:
Aλ=-log10Sλ-DλRλ-Dλ (4)
For transmission:
%Tλ=Sλ-DλRλ-DλX100% (5)
To calculate the area under the curve, Simpson rules and MATLAB will be used. And the formula of Simpson rule is showed as below. (6)
4.3 Experimental instrument
The Following are the instruments used in the experiments. (i) Deuterium Tungsten-Halogen Calibration Light Source (DH-2000-CAL)
Figure 4.1: DH-2000CAL.
The DH-2000-CAL Deuterium Tungsten Halogen Calibration Standard is a UV-NIR light source used to calibrate the absolute spectral response of a radiometric system. With the DH-2000-CAL and Spectra Suite Software, this can determine absolute intensity values at wavelengths from 220-1050 nm.
The DH-2000-CAL is specifically calibrated for use with optical fibers or a cosine corrector; the calibration data includes absolute intensities for wavelengths between 220-1050 nm at the fiber entrance port for both a bare fiber and a CC-3-UV Cosine Corrector.[7] (DH-2000-CAL Deuterium Tungsten Halogen Calibration Standard n.d.)
(ii) HR4000 High-Resolution Spectrometer
Figure 4.2: HR4000 High-Resolution Spectrometer.
The HR4000 Spectrometer is a versatile high-resolution spectrometer. The HR4000 has a 3648-element CCD-array detector from Toshiba that enables optical resolution as precise as 0.02 nm (FWHM). The HR4000 is responsive from 200-1100 nm, but the specific range and resolution depend on your grating and entrance slit choices. This novel combination of optics and electronics is ideal for applications such as characterizing lasers, measuring gas absorbance, and determining atomic emission lines. (HR4000 High-Resolution Spectrometer n.d.)
(iii) CUV-UV Holder for 1-cm Cuvettes
Figure 4.3: CUV-UV Holder for 1-cm Cuvettes.
The CUV-UV Cuvette Holder for 1-cm path length cuvettes couples via SMA-terminated optical fibers to Ocean Optics high-sensitivity miniature fiber optic spectrometers and light sources to create small-footprint spectrophotometric systems for absolute absorbance measurements of aqueous solutions. This compact cuvette holder is optimized for UV-VIS-NIR (~200 nm-2 µm) applications.
Two 74-UV lenses are mounted across a cell holder designed for square 1-cm cuvettes with a "Z" dimension or sampling region 15 mm from the bottom of the cuvette. Cuvettes are held in place with spring-loaded plungers, and the assembly base is equipped with channels for connection to a water bath for temperature regulation. (CUV-UV Holder for 1-cm Cuvettes n.d.)
These Laboratory-grade Bifurcated Optical Fiber Assemblies are Y-shaped assemblies that have two fibers of the same diameter side-by-side in the common end, or the tail of the assembly. From the nexus or breakout of the assembly, the two fibers diverge into two separate legs. You may specify that both fibers in the assembly are UV-VIS, VIS-NIR or one of each (a “mixed” bifurcated assembly). (Laboratory-grade Bifurcated Optical Fiber Assemblies n.d.)
(v) Computer
A computer is needed to analyse the results that transferred from Spectral Meter.
(vi) Oil Samples
Table 4.5: Data sheet of Oil Samples.
The table above is the data sheet of the oil samples which are tested during the research. Different oil samples are provided by different manufacturer which contain different furan, different ages and they were collected in Western Australia.
4.4 Experimental Procedure
Instrument Connection
1. Locate the cap on the front of the DH-2000-CAL.
2. Lift the cap on the front of the DH-2000-CAL to expose the optical input.
3. Insert the SMA connector barrel or CC-3-UV fully into the optical input.
4. Secure with the setscrew on the optical input.
5. Connect the Fibre optic cable to cuvette holder.
6. Connect fibre optic cable between cuvette holder and spectral meter.
7. Connect the Spectral meter to the computer with USB cable.
Software Configuration
A- The components function in a sampling system is as below: 1) The user stores reference and dark measurements to correct for instrument response variables. 2) The light from the light source transmits through an optical fiber to the sample. 3) The light interacts with the sample. 4) Another optical fiber collects and transmits the result of the interaction to the spectrometer. 5) The spectrometer measures the amount of light and transforms the data collected by the spectrometer into digital information. 6) The spectrometer passes the sample information to SpectraSuite Spectroscopy Operating Software 7) The software compares the sample to the reference measurement and displays processed spectral information
B- Follow the steps below to take an absorbance measurement using SpectraSuite: I) Taking Reference and Dark Spectra 1. Place SpectraSuite in Scope mode by clicking the Scope S icon in the Experiment mode toolbar or selecting Processing | Processing Mode | Scope from the menu. 2. Ensure that the entire signal is on scale. The intensity of the reference signal’s peak differs depending on the device being used. If necessary, adjust the integration time until the intensity is appropriate for your device. 3. Select File | New | Absorbance Measurement from the menu or click A to start the Absorbance Measurement Wizard. Then click Next >
4. Select the source of your absorbance measurement. Then click Next >
5. Turn on your light source and set your acquisition parameters so that the peak value reaches the recommended level. Click the Store Reference Spectrum () icon on the screen. Then click Next >
6. Block the light path to the spectrometer, uncheck the Strobe/Lamp Enable box, or turn the light source off. Then, take a dark spectrum by clicking (). You must take a dark spectrum before measuring absorbance. Then click Finish
II) Put the sample in place and ensure that the light path is clear and start the measurement.
Chapter 5
Measured Results:
Absorption and Transmission
5.1 Absorption Characteristic (Without Copper)
In this Experiment, Absorption of the wavelength will be recorded and graph will be presented with all the oil samples provided.
Figure 5.1: Absorption without Copper (0.04-0.019ppm).
From the figure above it shows that the furan content from 0.04 – 0.19 ppm which the more furan is, the more the absorbance of the light wave is.
Figure 5.2: Absorption without Copper (0.19-0.95ppm).
This graph shows the furan content of 0.19-0.95ppm which we can notes that it is similar to the previous graph which the higher furan content will have a higher absorbance.
Figure 5.3: Absorption without Copper (0.96-1.75ppm).
This graph shows furan content of 0.96-1.75ppm. But in this graph we can see that CVET1 1.13 ppm has lesser absorbance which will be taken off as error this is due to the working condition of the transformer.
Figure 5.4: Absorption without Copper (3.26-6.3ppm).
This graph shows the furan content from 3.26 – 6.3 which the results are similar as the previous graph.
According the figure 15, 16, 17 & 18, they show the simulation results of absorbance (OD) versus wavelength (nm) of different years and furan contents of power transformer’s oil. The aspect are from wavelength of 200-nm to 500-nm and absorbance are 0-OD to 2.5-OD. The furan contents ages of the transformer oil are from 0ppm to 6.3ppm and 1960 to 1990.
From the figures above, the results are as expected which shows that while the furan content are higher, the light absorbance will be higher. This will be discussed in chapter 6.By comparing the year, it is more likely that the older the transformer oil is, the more absorbance it will absorb, that shows the older transformer will have a worse condition then a newer transformer.
5.2 Transmission Characteristic (Without Copper)
The following are the graphs of transmission without adding any copper.
Figure 5.5: Transmission without Copper (0.04-0.19ppm).
According to the graph, the higher the furan is, the lower the transmission (%) is. It shows the furan content of 0.04-0.19ppm.
Figure 5.6: Transmission without Copper (0.24-0.915ppm)
The figure above shows that furan 0.54 ppm has the lowest transmission which had to take off. Other than that, all the results are as expected.
Figure 5.7: Transmission without Copper (0.95-1.75ppm).
The graph above shows the furan content of 0.95-1.75ppm which shows that 1.75 has the least transmission and highest furan content among the others.
Figure 5.8: Transmission without Copper (3.26-6.3ppm).
Transmission (%) is totally different from absorption which when the furan is higher, the less transmission is does, and absorption is the other way round.
According the figure 5.5, 5.6, 5.7 & 5.8, they show the simulation results of transmission (%) versus wavelength (nm) of different years and furan contents of power transformer’s oil. The aspect are from wavelength of 200-nm to 500-nm and absorbance are 0% to 100%. The furan contents ages of the transformer oil are from 0ppm to 6.3ppm and 1960 to 1990.
From the figures above, the results are as expected which shows that while the furan content are higher, the transmission will be lower. This will be discussed in chapter 6.By comparing the year, it is more likely that the older the transformer oil is, the less transmission it is, that shows the older transformer will have a worse condition then a newer transformer.
5.3 Absorption Characteristics (with copper once added)
During this section, copper dust is added into the oil samples, and it is recorded immediately after copper is added into oil sample instead of after the copper settle down. By doing this step, we can know that while a transformer is operating, the oil of the transformer will be circulating which means this step is showing the worst situation of the transformer oil when there is copper dust occur in the transformer.
Figure 5.9: Absorption with copper (0.04-0.1ppm).
Figure above shows light absorption of the furan content of 0.04-0.01ppm. The waveforms are not stable compared with the oil sample without dust.
Figure 5.10: Absorption with copper (0.15-0.54ppm).
Figure above shows light absorption of the furan content of 0.25-0.54ppm. The waveforms are not stable compared with the oil sample without dust.
Figure 5.11: Absorption with copper (0.86-1.75ppm).
Figure above shows light absorption of the furan content of 0.86-1.75ppm. The waveforms are not stable compared with the oil sample without dust.
Figure 5.12: Absorption with copper (4.33-6.3ppm).
From the results above, it can shows that after copper is added, the absorbance is unstable, the wave form is like a pulse moving up and down rapidly.
According the figure 5.9, 5.10, 5.11 & 5.12, they show the simulation results of absorbance (OD) versus wavelength (nm) of different years and furan contents of power transformer’s oil. The aspect are from wavelength of 200-nm to 500-nm and absorbance are 0-OD to 4-OD. The furan contents ages of the transformer oil are from 0ppm to 6.3ppm and 1960 to 1990.
From the figures above, the results are as expected which shows that while the furan content are higher, the light absorbance will be higher. This will be discussed in chapter 6.By comparing the year, it is more likely that the older the transformer oil is, the more absorbance it will absorb, that shows the older transformer will have a worse condition then a newer transformer. The waveform of are unstable since the copper dust are settling down.
5.4 Transmission Characteristics (with copper dust once added)
During this section, similarly, copper dust is added into the oil samples, and it is recorded once copper is added into oil sample instead of after the copper dusts were settled into the sample. Transmission of the sample is being recorded. In this step, we can know that while a transformer is operating, the oil of the transformer will be circulating which means this step is showing the worst situation of the transformer oil when there is copper dust occur in the transformer.
Figure 5.13: Transmission with copper (0.04-0.15ppm).
Figure above shows light transmission of the furan content of 0.04-0.15ppm. The waveforms are not stable compared with the oil sample without dust.
Figure 5.14: Transmission with copper (0.19-0.86ppm).
Figure above shows light transmission of the furan content of 0.19-0.86ppm. The waveforms are not stable compared with the oil sample without dust.
Figure 5.15: Transmission with copper (0.915-1.13ppm).
Figure above shows light transmission of the furan content of 0.915-1.13ppm. The waveforms are not stable compared with the oil sample without dust.
Figure 5.16: Transmission with copper (1.75-6.3ppm).
From the results above, it shows that adding copper will affect the transmission. This will affect the health of the transformer.
According the figure 5.13, 5.14, 5.15 & 5.16, they show the simulation results of transmission (%) versus wavelength (nm) of different years and furan contents of power transformer’s oil. The aspect are from wavelength of 270-nm to 500-nm and absorbance are 0% to 100%. The furan contents ages of the transformer oil are from 0ppm to 6.3ppm and 1960 to 1990.
From the figures above, the results are as expected which shows that while the furan content are higher, the transmission will be lower. This will be discussed in chapter 6.By comparing the year, it is more likely that the older the transformer oil is, the less transmission it is, that shows the older transformer will have a worse condition then a newer transformer. The waveform of are unstable since the copper dust are settling down.
5.5 Absorption Characteristics (with Copper dust settled down)
In this section, oil samples with copper settled down (which means the excess of copper are sink to bottom) of absorption are recorded. Copper dust in a transformer might be settled down while it is not operating, which means copper dust settled down is needed to be measure too since a transformer might be stop operating for a while and start running.
Figure 5.17: Absorption CU SETTLED (0.04-0.15ppm).
Figure above shows light absorption of the furan content of 0.04-0.01ppm. The waveforms are more stable than copper once added and slightly higher than oil sample without copper.
Figure 5.18: Absorption CU SETTLED (0.19-0.915ppm).
Figure above shows light absorption of the furan content of 0.19-0.915ppm. The waveforms are more stable than copper once added and slightly higher than oil sample without copper.
Figure 5.19: Absorption CU SETTLED (0.95 ~ 1.75ppm).
Figure above shows light absorption of the furan content of 0.95-1.75ppm. The waveforms are more stable than copper once added and slightly higher than oil sample without copper.
Figure 5.20: Absorption CU SETTLED (3.26-6.3ppm).
From the results above, the graphs are similar to the graph without copper but they had a higher absorbance.
According the figure 5.17, 5.18, 5.19 & 5.20, they show the simulation results of absorbance (OD) versus wavelength (nm) of different years and furan contents of power transformer’s oil. The aspect are from wavelength of 200-nm to 500-nm and absorbance are 0-OD to 4-OD. The furan contents ages of the transformer oil are from 0ppm to 6.3ppm and 1960 to 1990.
From the figures above, the results are as expected which shows that while the furan content are higher, the light absorbance will be higher. This will be discussed in chapter 6.By comparing the year, it is more likely that the older the transformer oil is, the more absorbance it will absorb, that shows the older transformer will have a worse condition then a newer transformer. The waveform of are getting back to stable since there is no moving particles in the transformer oil, but the transmission are higher than the transformer oil without anything added.
5.6 Transmission Characteristics (with Copper dust after settled down)
Similarly, this section, oil samples with copper settled down (which means the excess of copper are sink to bottom) of transmission are recorded. Copper dust in a transformer might be settled down while it is not operating, which means copper dust settled down is needed to be measure too since a transformer might be stop operating for a while and start running.
Figure 5.21: Transmission CU SETTLED (0.04-0.15ppm).
Figure above shows light transmission of the furan content of 0.04-0.15ppm. The waveforms are more stable than copper once added and slightly lower than oil sample without copper.
Figure 5.22: Transmission CU SETTLED (0.19-0.86ppm).
Figure above shows light transmission of the furan content of 0.19-0.86ppm. The waveforms are more stable than copper once added and slightly lower than oil sample without copper.
Figure 5.23: Transmission CU SETTLED (0.915-1.75ppm).
Figure above shows light transmission of the furan content of 0.915-1.75ppm. The waveforms are more stable than copper once added and slightly lower than oil sample without copper.
Figure 5.24: Transmission CU SETTLED (3.26-6.3ppm).
From the results above it shows that the graphs are similar to the transmission graph without CU.
According the figure 5.21, 5.22, 5.23 & 5.24, they show the simulation results of transmission (%) versus wavelength (nm) of different years and furan contents of power transformer’s oil. The aspect are from wavelength of 270-nm to 500-nm and absorbance are 0% to 100%. The furan contents ages of the transformer oil are from 0ppm to 6.3ppm and 1960 to 1990.
From the figures above, the results are as expected which shows that while the furan content are higher, the transmission will be lower. This will be discussed in chapter 6.By comparing the year, it is more likely that the older the transformer oil is, the less transmission it is, that shows the older transformer will have a worse condition then a newer transformer. The waveform of are getting back to stable since there is no moving particles in the transformer oil, but the transmission are higher than the transformer oil without anything added.
Chapter 6
Analysis of Measured Results
In order to calculate the area of light absorption and transmission, MatLab will be used. The following is the code for MatLab. The code is used to calculate every area of x axis 0.27 and added every area calculated to 500nm.
Figure 6.1 Matlab Code for Area Calculation.
6.1 Area Calculation underneath the Absorption Curve for Different Furan Contents
In this section, calculation of the areas of all absorption and transmission will be calculated.
Figure 6.2: Light absorption area for different furan contents without the Copper dust.
From the Figure above, the column below (239-402) are the area of the graph and the column above are the furan (ppm). The figure shows that the relationship between furan and the area are directly proportional which means the higher the furan is the higher the area it has. According to the research, the higher the area means that the health of the transformer is getting worse.
Figure 6.3: Light absorption area for different furan contents with copper settled down.
In compare with the area without copper, it shows with copper settled down are having more absorption which means the health of the transformer are getting worse. By adding copper into transformer oil, it will shorter the health of the transformer, since transformer oil is acting as insulating material and copper is not an insulating material. The transformer oil with 6.3ppm had the most area which has the most light absorption and it means the transformer health is the worst among all the others transformer oil tested.
Figure 6.4: Light absorption area for different furan contents with copper once added.
From the above figure 6.4, it shows that the lower the furan content is the lower the area it has. But due to the sinking system , timing of measuring, volume of the copper dust and the volume of copper dust settled down, the area of light absorption are not as seen in the figure in figure 6.2, 6.3. This kind of situation might occur in power transformer which some of the copper are already settled down and some of the copper dusts are circulating in the transformer oil. It can also be considered as the worst case in a transformer while copper dusts remain in transformer oil.
6.2 Area Calculation underneath the Transmission Curve for Different Furan Contents
Figure 6.5: Light Transmission area for different furan contents without the Copper dust.
Figure 6.5 shows the area of light transmission for different furan contents without copper dust in transformer oil versus furan contents. From the graph, it shows that the relationship between light transmission and furan contents are indirectly proportion, which means the higher the furan is, the lower the area of transmission is. While compare it with the year of the transformer, most of the transformer oil are in directly proportion which shows that the older the transformer oil is, the higher the furan is. In conclude, this graph proved that the higher the furan is the health of the transformer is worse, and the age of the transformer will be older.
Figure 6.6: Light Transmission area for different furan contents Copper Dust once added.
From the Figure above, we can see that the areas of transmission are not proportional with furan this is because the during the process of adding copper dust, the dust are still moving which will affect the reflection of light, similarly, it is the same as an operating transformer, the transformer oil will be circulating in the transformer with copper dust that is loosen from copper cable. It also shows a worse case of transformer oil that contain compound like copper which is not insulator. And it will depend on the time and amount of copper that’s circulating in transformer oil. Overall, it shows that copper dust will shorten the life of transformer.
Figure 6.7: Light Transmission area for different furan contents Copper Dust settled down.
Figure 6.7 shows that the area of light transmission for different furan contents without copper dust in transformer oil versus furan contents. From the graph, it shows that the relationship between light transmission and furan contents are indirectly proportion, which means the higher the furan is, the lower the area of transmission is. While compare it with the year of the transformer, most of the transformer oil are in directly proportion which shows that the older the transformer oil is, the higher the furan is. In conclude, this graph proved that the higher the furan is the health of the transformer is worse, and the age of the transformer will be older. While compared with Figure 6.6, we can see that the area of transformer with copper dust settled down is slightly lower than those in figure 6.6. This shows that adding copper dust into transformer oil will shorter the life of the transformer.
Chapter 7
Conclusion and Recommendations
7.1 Conclusion
In this thesis, it obtained more accurate results by analysing and comparing both light absorption and transmission. By using UV-Vis spectroscopy, the relationship between furan and light absorption and transmission can be observed clearly, and the health of the transformer can be easily estimated with the results obtained in chapter 5 & 6. The final result of the study has offered a great prospect to develop an innovative technique to develop an improved and easier technique to estimate the health of the transformers. The measured results demonstrated light absorption and transmission in according to furan contents of the transformer oil, which copper dust were added into the oil samples during the measurements. The analysis of the measured results shows that by adding copper dust into transformer oil, it will affect the light absorption and transmission which can also say that it will shorter the life of the transformer since copper acts like an electrical conductor, which short circuit might occurred in the transformer. Two situation are being tested which are copper dust being added and record immediately which similarly the same as the transformer oil had been circulating inside transformer and copper dust will be circulating together with transformer oil. And the other situation is copper dust settled down which is the same as transformer from a stop position to an operating position. And these two situation will shorter the life of the transformer.
7.1 Recommendation for Future Works
The research has developed a different way of measurement of furan in transformer oil. However, the presence of moisture in transformer oil will affect the response of UV-Vis spectral. The UV-Vis spectral response is analysed under the limitation of oil samples. The differences found are insignificant to create any substantial variation. Due to the limitation of oil samples, analyses at different condition of moisture (same furan content different moisture ratio) presented in transformer oil were not investigated. It is essential to analyse the spectral response at other moisture ratio for operability and more accurate of the developed technique. Therefore, testing of UV-Vis spectral response at different water moisture ratio is recommended.
Other materials should also be tested beside copper dust, copper are usually presented in the winding of a transformer, but iron and stainless steel should also be tested in order to obtained results to compared with copper dust.
In addition, this method will need to be tested with more field studies. The research had proven the relationship between the furan content and light absorption and transmission. However, the condition of oil sample are limited, it may be hard to identify the condition of the collected operating transformer oil, it is necessary to test the model with field studies prior to introduce it to the industries.
