Progres FYP sunflower oil

8/13/2019 Progres FYP sunflower oil

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The solid constitute the most extensive group of insulating material. Based on

physical and chemical properties, structure and production characteristic, the solid

insulating material are divided into several subgroups such as laminated plastic, paper ad

fabrics. Furthermore, the liquid insulating are insulating oils, which include petroleum,

vegetable oil and synthetic oil. The liquid insulating has different types of insulation from

each other in viscosity and in the value of their electrical properties. The gases insulating

include air and sulfur hexafluoride. Air is a natural insulated use for air gape in electrical

machinery and electrical equipments.

1.0.1 Insulation in transformer

Transformer is a static device that can transform electrical energy from one

circuit to another without any direct electrical connection. It is the exclusive use of

electric power for electromagnetic induction to transfer power at the same

frequency, usually with changed values of voltage and current. The transformer has

two parts to produce magnetic flux is primary and secondary winding. The primary

winding can be produce magnetic flux when it is connected to electrical sources

such as power supply. The magnetic flux produces by primary winding will be pass

through the core. The varying magnetic flux will be produce to other core. This core

called the secondary winding. The secondary winding also would on the same core

and can give output for transformer [1]. The figure 1.1 show the magnetic flux

produced by primary and secondary winding.

Figure 1.1: The flux magnet produced by coil [1]


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The heat in the winding will be moved to the oil for generated in the

transformer. The oil will be heated and will flow into the radiator by convection. The

temperature of transformer will be increases are entirely due to heat in transformer

does not disappear that right. It will cause damage to the paper insulating and fluids

insulating medium in transformers. Temperature control is important to ensure a

long life for the transformer. Transformer cooling system can be accelerated rate of

heat dissipation in the transformer.

The critical part of a modem power system is the transformer life

management but the transformer life depended on the insulating medium use. The

strength will be increase in electrical insulation but it is depends on the distance

between coils and winding in a transformer. Most of transformers used mineral oil

as an insulator and also acts as a cooling medium. The mineral oil is an excellent

dielectric and cooling medium. Moreover, the limitations of mineral oil are low

biodegradation and panic threats to human beings and ecosystem. Nevertheless,

the mineral oil has poor performance at high temperature [13]. That why it is

restricted in ecologically sensitive locations (indoor type applications). Furthermore,

this oil is high cost, it used of such oils certain special transformer application only.

There are several important features in determining the oil is suitable for use in

transformer and it depends on the physical, chemical and electrical properties in

order to achieve characteristics of insulation in the transformer. Figure 1.2 show

electrical power transformers.

Figure 1.2: power transformer


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breakdown voltage, permittivity and lost factor. It also must be analyze the result base on

chemical and electrical characteristic and compare result with the standard.

1.4 Methodology

This project has several steps that must be followed during the conduct of the

project. It seeks to ensure that the project has to run smoothly and successfully as the

objectives of the project. The first step that needs to be conducted that study the sunflower

oil and mineral oil as well as the study of the transformer. Besides, it also needs to identify

the characteristics of the sunflower oil and also mineral oil that it meets the required

characteristics to be used as transformer oil. After identifying the characteristics of each

sample of oil, the preparation is required where the project is to use different brands of

sunflower oil that Sunlico and Adela and it has made in Malaysian. For each brand will be

divided into two oil that where the oil should not be heated and heated. So, the project

provides all four samples, two samples of oil that has been heated and the two oils are

unheated on both the brand. The next step to make measurement based on physical and

electrical properties. After get on each test result, it should be analyzed so that the oil is

suitable or not site as transformer oil. Figure 1.3 shows flow chat for this project


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Figure 1.3: Project flow


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1.5 Outline

This thesis has five chapters. At the first chapter discuss about the objective and

the scope in this project. Chapter 2 discuss about the literature review which is mineral oil,

sunflower oil, electrical and physical properties. Chapter 3 discusses about the procedure

in this project. Chapter 4 discusses about the result and analysis in and lastly chapter 5

discuses the conclusion and recommendation in this project.


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CHAPTER 2

LITERATURE REVIEW

2.0 Mineral oil

Mineral oil used as a coolant insulating fluids in power transformer. The first idea

for mineral oil is used in 1892 by general electric in transformer that been designed by Prof

Elihu Thomson [4]. The mineral oils such as petroleum have some structure such as

Paraffinic, aromatic and naphthenic. It is obtained after making the fractional distillation of

crude petroleum. Until today, mineral oil are used in liquid filled transformer as the

insulating liquid. When in the service, the mineral oil liquid in a transformer undergo a

constant heat produce by the operation of the transformer and consequently it degradation

because of ageing process. The dark color formation and resin acids or mud liquid is the

result of ageing process.

Oil to be used in transformers are made by many regional and international refining

companies, each using a particular crude oil and refined oil, such as shown in figure 2.1.

Figure 2.1: Classification of mineral oil

mineral oil

crude

mineral oil

refined

mineral oil


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The aim for refining mineral oil is to remove or reduce waxes, sulphur, nitrogen and

oxygen compound and the aromatic hydrocarbon. After refining process, the mineral oil

has good insulation properties. Table 2.0 show the main type of mineral oil

Table 2.0: The main type of mineral oil

Type of mineral oil Chemical structure comment

Paraffin

Methane (CH4) is a gas

normal butane (C4H10) and

iso butene

Naphtene

It has ring structures withsix carbon atoms (withinsix-member rings) orfourteen carbon atoms(withinthree member rings)

Aromatic

It has six-member ringstructures and two groups:mono-aromatics (singlerings) and poly-aromatics(twoor more rings).

Mineral oil have several advantages over the other types of oils, it has higher

resistance to aging method. The transformer oil must have required low viscosity because

it can better for cooling of transformer [5, 6]. Usually, the mineral oil used for insulation

because it has excellent dielectric properties such as high dielectric strength and low

dielectric losses but poor in flash point and fire point characteristics. However, the oils are

non biodegradable and good long term performance [2, 3].


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The transformer oils are classified as liquid insulating which a good insulating in

transformer, it has some of properties that need to know to determine to provide the oil to

use into transformer. Some of the properties that need to know is physical, chemical, and

electrical properties. There are some basic factors to show the electrical properties of the

transformer oil, such as breakdown voltage, dielectric dissipation factor, dielectric constant

and volume resistivity. Breakdown voltage is most important for estimate the transformer

oil capacity of tolerance to electrical stress. When the dielectric dissipation factor increases

as the resistance reduces, dielectric dissipation factor and resistivity directly affect the

insulation of the electrical equipment.

2.0.1 Mineral oil properties

All the insulation oil for transformer should follow this specification. Table

2.1 show the mineral oil properties

Table 2.1: mineral oil properties [13]

PropertyTest

methodMineral oil

Density at 20C,kg/dm3 ISO 3675 0.88

Viscosity at 40CcSt

ASTMD445

8.9

Viscosity at -30CcSt

ASTMD445

1.080

Pour point,C

ISO 3016 -63

Flashpoint,C

ISO 2719 146

Water content,ppm

IEC 60814 70

tanat 90C (50Hz)IEC 60247 0.001


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2.1 Sunflower oil

Natural ester fluids base on renewably sourced has provide to been used for

insulating liquid in transformer. The natural ester oil was used in transformers since 1990.

This is because the oil has the properties better than traditional mineral oils. In the recent

years, the natural ester appear of clean and function technologies in high demand to used

as ecofriendly but in newest version, it are derived by compressing plant and animal tissue

such as natural ester is slower ageing rate, less total operating cost (initial cost and

operating cost) and low noise level. Moreover, vegetable oil could be reduce the

exploitation and end life cost in transformers. It also could be safety and health problem

and appropriated responds to environment [2].

The natural esters like sunflower oil are used successfully in transformers [2]. For

this project, the sunflower oil use as an alternative for mineral oil in transformer because it

is non-fossil and also 100% environmental friendly. The first extraction of sunflower oil in

Europe was in the early 18th century. The sunflower oil is a combination of

monounsaturated and polyunsaturated fats at low levels of saturated fat, but it provides a

lot of vitamin E compare with other vegetables. Besides, the sunflower oil also has health

benefits, a good frying performance and value for a light taste.

Sunflower oil has a fatty acid consisting of a linear hydrocarbon chain and ended

with carbolic function. The molecules contain in the chain has an even number of carbon

atoms and the chain may be saturated or unsaturated chain is compose of mono-, tri-and

di-. Then even numbers of carbon atoms normally used for number 8 to 22 in triglycerids.

HOOC-(CH2)16-CH3 is a crude formula that represents the expression of C18:0 in which

both queries numbers correspond to the number of carbon atoms and unsaturated chains

to bound (s) in each molecule [7]. The natural of the fatty acids components of triglycerides

plays an important role for determining the physical chemical properties of bio-oil. Table

2.2 show the characteristic by the relative quantities of fatty acids.


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Table 2.2: Typical fatty acid profiles (%) of sunflower oil [7]

Fatty acids Sunflower oils

C16:0 5.77

C18:0 3.97

C18:1 27.2

C18:1(OH)* 0.00

C18:2 59.2

C18:3 0.23

C20:0 0.24

C20:1 0.13

C22:0 1.44

C22:1 0.00

Other 1.82

Therefore, higher viscosity of the oil because the chemical is stable in saturated

fatty acid but in triple unsaturated fatty acids, the viscosity is lower because the chemical is

unstable [2]. The sunflower oil insulation have tabulated in table 2.3. It shows sunflower oil

properties.

Table 2.3: Sunflower oils insulation properties [16]

Property Sunflower oil

Breakdown voltage (kV/m) 34

Flash point (C) 260

Fire point (C) 270

Viscosity (cSt) 132


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2.2 Electrical properties

2.2.1 Breakdown voltage

Breakdown voltage is one of important properties to define the efficiency of

oil as an insulator. The ability of the oil (acting as a dielectric) to oppose the flow of

a current is determine by test which show its dielectric strength. Among these are

the specific of resistance that a dielectric offers under moderate conditions of

voltage. Moreover, the ability to prevent arcing between two electrodes at high

electric potentials or to prevent arcing between the electric source and ground. The

quality of the oil can be influenced by the presence of impurities like humidity,

particles and gases. The presence of water in the oil can cause a rapid drop in the

dielectric strength. However, dielectric strength will increase if there are impurities

in the oil. Due to oil is used for insulation in a transformers, it have to release of

moisture and oxidation in the oil for need to make a strong insulating material in

transformers. [12].

The liquid fraction in the gas is connection dependent avalanche ionization

of atoms, causing the collision of electrons that have been supplied in the field. The

electrons must be removed from the liquid cathode available. Pure liquid is a liquid

that has a pure chemical which can not contain any impurities and simple structure

in pure chemistry. The breakdown mechanism explains breakdown only of highly

pure liquid and do not applied commercially available in liquid. Conductivity may be

obtained after the electric field is low at less than 1kV/cm. it will be due to impurities

found after purification. However, the current will increase as the area is high (>

100kV/cm) [12].

Breakdown strength affect the breakdown strength in oil once will affect the

insulation in the transformer. There are several factors that can affect the

breakdown strength to affect the breakdown strength of oil such as the field,

separation gap, the cathode work function and cathode temperature. Therefore, the

dielectric fluid includes a conduction mechanism of charge and the process leading


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to the breakdown. It is also important to develop high-voltage technology and pulse

power systems to form a transformer that works well. [12].

2.2.2 Dielectric loss, Tan

Dielectric dissipation factor is important properties in the liquid insulating.

The electrical energy absorbed by the material from the electric field and it will

appears in the form of heat within the material. The dielectric dissipation factor can

be expressed as

(1.0)

The electrical loss tangent is defined by the angle between the capacitor

impedance vector and negative reactive axis [16]. Figure 2.2 show the leakage

current per phase to an insulator.

Figure 2.2: The leakage current per phase to an insulator

The leakage current leads the voltage by 90 because the voltage is

instantaneous voltage. If not insulating, the current leads the voltage with an angle

little bit shorter the 90. It can generates a leakage current,

and the


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displacement current . From the phasor diagram in figure 2.2, it can be

represents the value of

. From this equation, applying the substitution on

I and IC, it will give final expression of

(2.0)

The dissipation according IEC 60247 is the tangent of the loss angle here is

described as the angle difference between applied voltage and the resulting current

deviation from

. The low value of tangent delta is needed so that insulation oil

can works as good insulation oil. If the value of tangent is high, it could be an

indication of presence of contaminants in liquid transformer.

2.2.3 Permittivity

The dielectric constant is purely a relative number comparing the capacity of

a material for storing electricity to that of air. It also depends on the physical

parameters of temperature density, molecular weight and dipole moment. The

capacity of the material for storing electricity decreases as the frequency rises

above the corresponding orientation time. The dipoles not longer fully orient

themselves, the material could be hold as large an electric decrease [16].

The relationship between the dielectric constant and the loss factor as the

frequency can be increases. The equation for the complex dielectric constant:

(3.0)

Where the imaginary represents the magnitude of the dielectric loss can

be contribute by the leakage current and the polarization, is complex permittivity.


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2.3 Physical properties

2.3.1 Viscosity

Viscosity of liquid used in electrical equipment can be provided the

information on flow characteristic and heat transfer properties. It is known as the

drag where it will measure the frictional properties of the liquid. It also has a

function of temperature and pressure in the liquid. While the viscosity of liquid and

gases will be change with temperature and pressure, it can be effect viscosity in

different ways [8]. The function of the moving part such as pump can be effect if the

viscosity is higher than at room temperature. The start up of apparatus in cold

climates will be effect in high viscosity. Viscosity of the oil will be affected by the

pressure drop, flow rate of oil and oil cooling system.

Dynamic viscosity and kinematic viscosity is two distinct forms in the

viscosity. Dynamic viscosity is the tangent force in the slide. The area of tangent

force per units is required to slide one layer (A) against another layer (B) are

maintain at a unit distance [9]. Figure 2.3 shows the simple shear of the liquid film.

Figure 2.3: Simple shear of the liquid film [9]

In figure 2.3, Force (F) causes layers A and B to slides at velocities V 1and

V2. Since the viscosity of the fluids is defined is a measure of the resistive flow

under gravity [9]. Kinematic viscosity requires of density of the liquid () at the


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pressure and the time of flow is proportional to the kinematic viscosity of the fluids

(). Kinematic can be by the relationship [9].

(4.0)

Where is dynamic viscosity.

The units of kinematic viscosity is the centistokes (cSt) and used by the

international standard organization (ISO). Viscosity classification using ISO shows

in table 2.4.

Table 2.4: ISO grade classification (ISO 3446) [10]

ISO viscosity grade

notification

Kinematic viscosity

limits, cSt at 40C

Midpoint kinematic

viscosity, cSt at

40CMin Max

ISO VG 2

ISO VG 3

ISO VG 5

ISO VG 7

1.98

2.88

4.14

6.12

2.42

3.52

5.06

7.48

2.2

3.2

4.6

6.8

ISO VG 10ISO VG 15

ISO VG 22

ISO VG 32

ISO VG 46

ISO VG 68

ISO VG 100

ISO VG 150

9.0013.5

19.8

28.8

41.4

61.2

90.0

135

11.016.5

24.2

35.2

50.6

74.8

110

165

1015

22

32

46

68

100

150

ISO VG 220

ISO VG 320

ISO VG 460

ISO VG 680

ISO VG 1000

ISO VG 1500

198

288

414

612

900

1350

242

352

506

748

1100

1650

220

320

460

680

1000

1500


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2.3.2 Moisture content

Moisture in transformer oil has the effects the insulation of solid and liquid

insulation. Therefore, the dielectric breakdown strength of the insulation will have

the effect of the water. Its water content will be rises above two to three percent by

weight after the breakdown of the paper insulation decreases [11]. Moisture in the

oil shows up above 50 to 60ppm but it is depends on temperature. Accepted of

water in oil are shows in table 2.5.

Table 2.5: Maximum allowable moisture in oil [12]

Voltage level (kV) Maximum moisture (ppm)

5 30

15 30

35 25

69 20

138 and up 15


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CHAPTER 3

METHODOLOGY

3.0 Sample

In this experiment, the sunflower oil use for the sample but it have different brand

from the local market. Every brand needs to provide two samples of the oils which

one of the sample have to remove moisture and other samples used the original oil

which dont remove moisture of the oils. It aims to compare between the samples

from in terms of electrical and physical properties. Therefore, it is should to make

measurements using several parameters including breakdown strength, dielectric

dissipation, permittivity, viscosity and moisture content

3.1 The oil sample conditioning

The samples have to prepare bottles or jar was required to clean to prevent

moisture in the oil increased in the period in which the oil is stored in the container. In the

event of humidity in oil will be affect to the dielectric properties such as dielectric loss and

breakdown stress in the oil. Fuel humidity is likely to require a reduction of thermal aging

on the dielectric properties. Therefore, test humidity needed to reduce humidity on the oil

through a vacuum process. The oven equipped with a heating device to speed up the

evaporation process using a low temperature to remove moisture. It can reduce the

problem of unstable thermal degradation of the materials. The temperature use in this oven

is 100C and took one day for this process. Figure 3.1 shows the sample after heated


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Figure 3.0: The sample after heated

3.2 Breakdown voltage measurement

The breakdown voltage was measured according standard IEC 60156 insulating

liquid. It also measured for this property containing two electrodes of specified gap is

2.5mm and high voltage applied in this sample. The frequency is 50Hz will be applied with

increasing the voltage at a rate of 2kV/s until breakdown occurs. This measure needs to

take a reading at least five value of the average value from this samples. There has

several procedures that should be followed. Figure 3.1 show breakdown voltage

equipment.

Figure 3.1: breakdown voltage equipment


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3.2.1 Sample preparations

The electrode and test cup should be clean up and dry until completely. It is

performed to prevent pollution or have oil or other solvent during this test. If

have another solution, the average value is not same or opposite of the

value on electrical properties in literature review.

The distance between the two electrodes must set 2.5mm. After that, the

electrode should be locked to prevent movement of the electrode such that

the electrode comes into contact between the electrodes. Figure 3.2 show

gap between electrode

Figure 3.2: Gap 2.5mm in test cup

The samples have to be filled in the test cup until it is almost full and will

leave about 3% of the cup as a free space for air. Time must be set for

make measurement.

3.2.2 Measurement procedures

After measurement, record the data for the first measuring. After record n

want to start next measure, should be wait 1 minute that have no gas

bubbles present within the electrode gap.

2.5mm


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This measurement needs to be repeated with the same sample up to 5

times of the measurement to see the average value.

3.3 Viscosity measurement

This test measure according to the ASTM D445 and this measurement equipment

named as viscometer. It intended to get the viscosity found in the oil. This viscometer used

spindle to find the speed that should be used to take a more accurate reading of a sample.

The spindle has a variety of different sizes and it depends on the viscosity, spindle use a

small sample size which is suitable for high viscosity. The measurement of sunflower oil

use spindle size s-02. Figure 3.2 show viscometer equipment for measure viscometer.

Figure 3.3: Viscometer

The speed used to take readings of 100, 60, 50, 30, 20 and 10 rpm where in each

speed has some value percentage torch to determine the necessary speed to make

viscosity measurements for these samples. The value for percentage torch needed for a

speed is above 10% because the value for viscosity is accurate. If the value is below 10%,

Spindle(s-02)


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the value of viscosity is not accurate. Therefore, the speed cant be used to take readings

for the viscosity. So, this sample used speed 100rpm and the value of torch is 28.4%.

3.3.1 Measurement procedure

Make sure the spindle and beaker to be used for this measurement

in a clean and dry before use. Its because, to avoid no solution

available on the equipment prior to conducting the test.

500ml oil must be prepared in a beaker and make sure there are no

air bubbles in the spindle. The used of oil also depends on the

spindle where the oil is needed for these measurements have

exceeded any marks or labels on the spindle.

Set time and speed required for this test. The time required is 5

minutes while the speed is 100rpm after knowing the torch at each

speed in which more than 10%.

Readings must be repeated three times on each sample during the

test. Record for all the result.

3.4 Moisture content measurement

The measurement of moisture in oil has two methods which Karl Fischer reaction

method and the pressure gauge method. Usually, this test measured according standard

IEC 60814 and use Karl Fischer for this test. The oil in the transformer is designed to

provide good electrical insulation for work in the transformer. When the moisture in the oils

has to increase, the properties of the oil will be reduced at the expense of the breakdown

voltage. However, the properties of the oil are important when the temperature changes in

a transformer.


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While performing this test, the oil temperature must be set to see a change of water

in the oil. Temperature is also important where the acid will be formed during the oxidation

of the oil. Therefore, the water will dissolve in oil due to acids formed during oxidation.

Water content in the oil is measured as ppm.

3.5 Dielectric measurement

The measurement of dielectric dissipation factor and permittivity test has to

according for standard IEC 60247. This test was conducted using cells in which the cell

has two parts, low voltage and high voltage. The samples used must meet the cell to

prevent the air accumulates in the cell during the test done. This test measured the empty

condition and there is the capacitance is determined to do the measurement. This sample

make measurement using Schering bridge with gas a standards capacitor. This cells must

are clean before performing any tests. It is done to avoid contamination in the cell.


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CHAPTER 4

INITIAL WORK

4.0 Result and discussion

4.0.1 Breakdown voltage

The result for measured the breakdown voltage of sunflower oil have been

listed according to the sample to be used for this measurement. This measurement

is done by using four samples, two samples of oil that has been heated and the rest

of the sample is unheated. For each sample to be perform the measurement of the

five tests. Table 4.0 shows the results obtained from these measurements.

Table 4.0: Result for breakdown voltage measurement of the sample

Sample

Breakdown voltage (kV)

Average value(kV)Measurement 1 2 3 4 5

Sunlico

Heated 10.0 9.3 16.2 9.3 10.3 11.0

Unheated 10.0 9.5 10.2 15.2 16.1 12.2

Adela

Heated 59.8 47.8 57.2 61.8 31.1 51.5

Unheated 12.5 12.6 14.2 17.3 12.0 13.7


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Based on table 4.0 above, it shows the readings taken during a breakdown

voltage measurement on four samples of different brands. Based on the average

value of the oil that has been heated to a brand Adela is a high value of 51.5kV.

This is because the oil has been heated with low humidity so it does not affect the

breakdown voltage. If compared with mineral oil exist in the literature review is

more than 70kV compared with sunflower oil. According to the characteristics of

transformer oil, the value of the breakdown voltage is ideal for use as liquid

insulation for high efficiency and good for insulation and will be use in the

transformer.

The value of breakdown voltage are low, it is likely due to the high moisture

in the oil and not good for insulation. The measured for the brand sunlico, the

difference for heated and unheated are lower value in breakdown voltage. it is not

good to used in a transformer due to its efficiency of the insulation is low. The

insulation in transformers is important to respond with a very high resistance to the

flow of electric current in a transformer. The minimum value of the breakdown

voltage to safety used in transformer is 30kV [14].

4.0.2 Viscosity

The measurement for the viscosity of the oil is only done for the sample of

the oil that has been heated. The sample must be performed by three time of test.

The results obtained are recorded for this measurement in Table 4.1

Table 4.1: Result for viscosity measurement of the heated sample

Sample for heated

Cp (MPa s-1) at 100rpm

1 2 3

Sunlico 113.6 113.6 113.6

Adela 114.4 114.4 114.4


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Based on the result of the measurement of viscosity, the value in the two

samples no difference. The sample for the brand sunlico is 113.6 MPa s -1, while

114.4 MPa s-1is the viscosity of the sample for brand Adela. Based on the viscosity

of mineral oil is 8.9 cSt at temperature 40C. The sample used for this

measurement is the oil has been heated and has also reduced the moisture in the

oil.

The viscosity is the flow resistance in the normal state. The transformer

requires that transformer oil has a lower viscosity to reduce the resistance to the

flow of oil that does not touch the convectional cooling transformer. It is also safe

for use in transformer condition better on a long run as cooling. If high viscosity, it is

not suitable for use in a transformer because the transformer cooling process

requires high temperatures. Usually, the temperature is reduced to increase the

viscous liquid. Therefore, the viscosity should be high for the cooling process in

transformers. The sunflower oil can be used as the viscosity is high and similar for

mineral oil [15, 17].


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REFERENCES

[1] http://www.electrical4u.com/what-is-transformer-definition-working-principle-of-

transformer/

[2] A. Raymon, P.S.P., M. P. E. Rajamani and R. Karthik, Enhancing the Critical

Characteristics of Natural Esters with Antioxidants for Power Transformer

Applications, IEEE Transactions on Dielectrics and Electrical Insulation, June

2013. Vol. 20: p. No. 3

[3] D.C. Abeysundara, C.W.a.J.R.L., K.A.I. Gunatunga and K.C. Obadage, Coconut

oil as an alternative to transformer oil. ERU Symposium, November 2001.

[4] MCSHANE, B.C.P., vegetable oil based dielectric coolant, in IEEE industry

applications magazine. may/june 2002.

[5] Milan Spohner, "Comparison of mineral oil with natural and synthetic oil".

[6] Darma, S.I.S., Dielectric Properties of Mixtures between Mineral Oil and Natural

Ester,IEEE, 2008.

[7] HOANG, Y.B.a.L.C., Vegetable oils as substitute for mineral insulating oils inmedium voltage equipments. 2004.

[8] base oil handbook, NYNAS.

[9] T. K. G. D. H. L. P. N. K. D. a. K. Y. R. DABIR S. VISWANATH, Viscosity of liquid,

Springer, 2007.

[10] T. V. O. a. G. L. Grune, "Low temperature viscosity behavior of transformer oils".

[11] Lewand, L., Understanding water in the transformer oil, in Chemists Perspective.

2002..

[12] Wadhwa, C.L., High voltage engineering. 2007, New age international (P) limited,

publishers.

[13] M. Pompili, C.M.a.R.B., Comparative PD Pulse Burst Characteristics of

Transformer Type Natural and Synthetic Ester Fluids and Mineral Oils, IEEE

Transactions on Dielectrics and Electrical Insulation, December 2009. Vol. 16,.
http://www.electrical4u.com/what-is-transformer-definition-working-principle-of-transformer/http://www.electrical4u.com/what-is-transformer-definition-working-principle-of-transformer/http://www.electrical4u.com/what-is-transformer-definition-working-principle-of-transformer/http://www.electrical4u.com/what-is-transformer-definition-working-principle-of-transformer/http://www.electrical4u.com/what-is-transformer-definition-working-principle-of-transformer/


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[14] Alan DARWIN, C.P.a.P.F., The use of natural ester fluids in transformer

[15] Ilori, E.W.A., Understanding the insulating properties of transformer oil for

efficiency performance.

[16] R. Bartnikas, Dielectrics and Insulators, 2000.

[17] Imsak, F.S.I.S.L., Study on the Characteristics of Palm Oil and its Derivatives as

Liquid Insulating Materials. Proceedings of the 7th Intemational Conference on

Properties and Applications of Dielectric Materials, 2003.

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Progres FYP sunflower oil