Ivat Lab Report. s4g4 (1)

8/11/2019 Ivat Lab Report. s4g4 (1)

1/25

SEE 4722 (4)

FACULTY OF ELECTRICAL ENGINEERING

UNIVERSITI TEKNOLOGI MALAYSIA

JOHOR BAHRU CAMPUS

JOHOR

INSTITUT VOLTAN DAN ARUS TINGGI

(IVAT)

TITLE: EFFECT OF CONTAMINATION TO THE

CAPACITANCE PROPERTIES FOR MEASURING

BREAKDOWN VOLTAGE OF GLASS INSULATOR

DSUPERVISOR: DR. ZURAIMY BIN ADZIS

MEMBERS:

SYAHEEDULLAH BIN YAHYA (M1)

THAAHA BIN ABDULLAH (M2)

NAIMAH BINTI MOHAMAD (M3)

CONTENT


2/25

1

ABSTRACT

1.0 INTRODUCTION

1.1 Background 1

1.2

Objective ...5

2.0 METHODOLOGY

2.1 Procedure and equipment ..... 6

2.1.1 Part 1 : Sample preparation ......6

2.1.2

Part 2 : Testing for capacitance, power factor

(tan), and leakage Current ...8

2.1.3 Part 3: Testing for breakdown voltage of each sample .13

3.0 RESULT AND DISCUSSION

3.1 Measuring Capacitance, Dissipation/Power Factor

and Leakage Current (Part 2) ..... 16

3.2

Testing for breakdown voltage of each sample (Part 3) ......18

3.3 Test for ESDD (Equivalent Salt Deposit Density) ......19

4.0 CONCLUSION ....22

5.0 REFERENCES ....23


3/25

2

ABSTRACT

This report is about the experiment on the glass insulator to determine the effect

of the contamination to the flash over. The experiment was conducted for 2 days in

Institute of High Voltage and Current. All the procedure is stated in here was conducted

successfully. All the data collected are also recorded in this report.


4/25

3

INTRODUCTION

5.1 Background

5.1.1 Transmission Tower

Transmission tower is a tall structure, usually a steel lattice tower, used to

support anoverhead power line.They are used in high-voltage AC and DC systems,

and come in a wide variety of shapes and sizes. Typical height ranges from 15 to 55

metres (49 to 180 ft), though the tallest are the 370 m (1,214 ft)

towers of a 2700-metre-long. In addition to steel, other

materials may be used, including concrete and wood.

There are four major categories of transmission

towers:suspension,terminal,tension,andtransposition.Some

transmission towers combine these basic functions.

Transmission towers and their overhead power lines are often

considered to be a form ofvisual pollution.

5.1.2 Flash over

Flash over is the voltage at which an electric discharge occurs between two

electrodes that are separated by an insulator; the value depends on whether the insulator

surface is dry or wet. It is also known as sparkover voltage. Sometimes, when a direct

lightning stroke occur on a tower, the tower has to carry huge impulse currents. If the

tower footing resistance is considerable, the potential of the tower rises to a large value,

steeply with respect to the line and consequently a flashover may take place along the

insulator string. This is known as back flashover.
http://en.wikipedia.org/wiki/Structurehttp://en.wikipedia.org/wiki/Lattice_towerhttp://en.wikipedia.org/wiki/Overhead_power_linehttp://en.wikipedia.org/wiki/Suspension_towerhttp://en.wikipedia.org/wiki/Dead-end_towerhttp://en.wikipedia.org/wiki/Transposition_towerhttp://en.wikipedia.org/wiki/Visual_pollutionhttp://en.wikipedia.org/wiki/Visual_pollutionhttp://en.wikipedia.org/wiki/Transposition_towerhttp://en.wikipedia.org/wiki/Dead-end_towerhttp://en.wikipedia.org/wiki/Suspension_towerhttp://en.wikipedia.org/wiki/Overhead_power_linehttp://en.wikipedia.org/wiki/Lattice_towerhttp://en.wikipedia.org/wiki/Structure


5/25

4

5.1.3 Leakage Current

Leakage current is the current flow through the protective ground

conductor to ground. In the absence of a grounding connection, it is current that

could flow from any conductive part or the surface of non-conductive parts to

ground if a conductive path was available (such as a human body). There are

always extraneous current flowing in the safety ground conductor.

There are 2 types of leakage current; AC and DC. DC leakage current

usually applies only to end-product equipment, not to power supplies. AC

leakage current is caused by a parallel combination ofcapacitance and DC

resistance between a voltage source (AC line) and the grounded conductive

parts of the equipment. The leakage caused by theDC resistance usually is

inigsificant compared to the AC impedence of various parallel capacitances.

5.1.4 Dissipation Factor (tan)

Dissipation factor (tan )or DF is defined as the ratio of the ESR and

capacitive reactance. Dissipation factor is also known as the tangent of the loss

angle and is commonly expressed in percent.

=

Equivalent Series Resistance or ESR for short is the sum of the ohmic losses of

the dielectric, materials and connections used in the construction of the

capacitor.

= =

2

ESR is normally expressed as a maximum value at specified

frequencies, 120 Hz and 100kHz for aluminum electrolytic and tantalum

capacitors and 100kHz for film capacitors. Impedance is the total resistance the

capacitor represents to alternating waveforms. This includes the inductive and

resistive components.


6/25

5

= + ( + )

The equivalent circuit is shown below;

Below is a graphical illustration of how the above parameters change

with frequency.

An important observation is the Fr parameter. Fr is the self-resonant

frequency. Defined as the frequency where Xl and Xc are equal.

=1

2

At this frequency the impedance is equal to the ESR. Below self-

resonance the Xc component is dominant and the capacitor behaves like a

capacitor. Above the self-resonant frequency the inductive component is

dominant and the capacitor behaves more like an inductor.


7/25

6

5.1.5 ESDD

Equivalent Salt Deposit Density (ESDD) is used to measure the

pollution based on average density of soluble salt. The amount of salt will affect

the conductivity resulting from the solution of polluted deposits gathered at the

surface of the insulator.

=(5.7 [1 ( 2 0)])/3

Where,

= solution temperature, C

= volume conductivity at temperature C, S/m

V = volume of the water, cm3

A = area of the cleaned surface, cm2

b = factor depending on the temperature

5.2 Objective

1. To study dielectric properties of insulator

2. To identify causes o flashover occurring at insulator

3. To measure leakage current and calculate value of ESDD that influence

insulation performance

4. To study the effect of contamination saturation towards insulation

properties.


8/25

7

METHODOLOGY

2.1 Procedure and Equipment

This section describe the procedure and the step taken to set up the experiment.

In order to achieve the objective of the experiment, there are three test being conducted

using four glass insulator samples with different amount of contaminant. First test

conducted to get leakage current, power factor, and capacitance for each contaminant

.Second experiment was to get the breakdown voltage value for each contaminantdensity, and the third experiment was to test the ESDD of each samples after undergone

the first and second test. The glass insulator used, represent the insulating material in

high voltage transmission. The experiment conducted in a closed room under the

technician supervision and all safety precaution was taken into serious action.

2.1.1 Part 1: Sample preparation

Equipment:

Four insulating glass

Salt

Weight scale

Distilled water

Procedure:

1. Glass insulator are washed using tap water to remove impurities

2. Glass insulator was classified into four sample which are A(no

contamination),B(small),C (medium) and D(high)

3. Sample A was dipped into 5 litre of distilled water with 0g salt

4.

Sample B was dipped into 5 litre of distilled water with 110g of salt.


9/25

8

5. Sample C was dipped into 5 litre of distilled water with 220g of salt

6. Sample D was dipped into 5 litre of distilled water with 330g of salt

7.

All sample were kept in a room until it completely dry.

Figure 3.1 Preparing contamination to the insulator

Figure 3.2 Insulator dried


10/25

9

Part 2:Measuring Capacitance, Dissipation/Power Factor and Leakage Current

1) The sample A to be testes ware connected to the high voltage and ground.

Fig 1: connect the insulator to the PDF test Set (Bridge)

2) Switch of the Measuring Bridge INST.PWR.SUPPLY and INST.CONTROL is turned ON.

Fig 2: Switch of the INST.PWR.SUPPLY and INST.CONTROL

PinHigh Voltage

Connection

CapGround

Connection

Power Button


11/25

10

3) The operating cycle and the injection voltage (5kV) were set

Fig 3: Step to set up the setting

4) The temperature also need to be set up and updated if the temperature changes.

Fig 4: Room temperature

1. Test Mode

2. UST A/

UST B 3. IdentityInput

6. Run5. Enter

4. Fill the

number

Temperature

25


12/25

11

Fig 5: Step to set up the temperature

5) The safety button is pushed before turning ON the High Voltage source and always

being pushed throughout the experiment.

Fig 6: The safety button was kept pressed throughout the voltage injection

2. Fill in the

temperature

1. PF/tan

2. Enter

Safety

Button


13/25

12

6) The test voltage is increased until 5kV.

Fig 7: the test voltage is increased slowly until reach 5kV

7) The RUN button is pushed to inject the high voltage.

Fig 8: Run button

Test

Voltage

6. Run


14/25

13

8) The readings are taken when the counter finished the counts until 10.

Fig 9: The reading were taken after the counter counted until 10

9)

After all readings have been taken, the test voltage is decreased until reach zero.

10)

The INST.CONTROLis pushed to turn off. Then, the safety button is released.

11)After ensuring that no high voltage source is being injected, the high voltage

connection is discharged by using a discharger rod before the sample were replaced.

Fig 10: Discharger rod discharged the high voltage

CapacitanceDissipation/

Power FactorTest

Voltage

CounterLeakage

Current


15/25

14

12)The connections on the insulator are disconnected.

13)Step 3 until step 12 is repeated for other samples, insulator B, insulator C and

insulator D.

14)After finishing the experiment, the switch of the machine is turned OFF.

Part 3: Testing for breakdown voltage of each sample

1) The circuit to be used has been set up by the technicians.

Fig 11: Circuit to be used for breakdown test

2) The sample was connected to high voltage and ground source

Fig 12: Sample was connect to high voltage and ground source

Tools used for insulation

outboardTransformer

Capacitor

Cap Ground

connection

Pin High Voltage

connection


16/25

15

3) The machine is turn ON and the high voltage were inject, the sequence is follow.

Fig 13: Digital Measuring Instrument DMI 551 used to measure the voltage

breakdown

1 SE

2 SI

3 SB1

4 SB2

5

SB3

6 S/UP

7 S/DOWN

Sequence to increase voltage : 1 2 3 4 6

Sequence to decrease voltage : 6 5 2 1

1

2

3

4 56 7


17/25

16

4) The voltage is increased until flashover occur on the insulator.

Fig 14: Flashover occur

5)

After the flashover occur, the voltage is decreased immediately until reach zero volt.

6) The value of voltage during the flashover occur were record.

7) After ensuring that no high voltage source is being injected, the high voltage

connection is discharged by using a discharger rod before the sample were replaced.

Fig 15: Discharger rod discharged the high voltage

8)

The connections on the insulator are disconnected.

9) Step 2 until step 8 is repeated for other samples, insulator B, insulator C and

insulator D.

10)

After the experiment finished, the machine is turned OFF.


18/25

17

RESULT AND DISCUSSION

3.1Measuring Capacitance, Dissipation/Power Factor and Leakage

Current (Part 2)

Dissipation Power Factor

Insulator

Contamination

Clean Light Medium High

* Dissipation

Factor, tan

0.0459(2.6) 0.272(15.22) 0.348(19.19) 0.420(22.78)

* Power Factor 0.0461(87.36) 0.261(74.87) 0.327(70.91) 0.390(67.05)

* Capacitance,

pF

48.78

54.92

55.57

59.51

* Leakage

Current, mA

0.076mA 0.086mA 0.087mA 0.093mA


19/25

18

Fig 16: Relationship between Leakage Current and Dissipation Factor

From the relationship, it is shown that the higher the dissipation factor which is

the higher leakage current in the insulator. That will causes flashover occur faster.

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.080.09

0.1

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45

leakagecurrent,mA

dissipation factor

Relationship Between Leakage Current and

Dissipation Factor


20/25

19

3.2Testing for breakdown voltage of each sample (Part 3)

Breakdown Voltage:

Condition Clean Light Medium High

test 1 2 1 2 1 2 1 2

*Breakdown 67.61kV 68.57kV 63.47kV 65.22kV 62.65kV 63.88kV 58.43kV 59.07kV

Fig 17: Relationship between Breakdown Voltage and Dissipation Factor

From the relationship, it is shown that the higher the losses in the insulator

which is the higher the dissipation factor, the lower the breakdown voltage value.

Breakdown will occur in shorter period for those with higher dissipation factor than

that with lower dissipation factor. Due to flashover occur at test 1, the contamination

were reduced. And there is a difference between test 1 and test 2. Are available for test

2 breakdown voltage is higher than test 1.

56

58

60

62

64

66

68

70

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45

BREAKDOWNVOLTAGE,

kV

DISSIPATION FACTOR

Relationship Between Breakdown Voltage and

Dissipation Factor

test 1 test 2


21/25

20

3.3Test for ESDD (Equivalent Salt Deposit Density)

Equipment:

Sample A,B,C and D

ESDD tester

600 ml distilled water

Pail

Procedure:

1. Each sample are washed with 600ml of distilled water and being pour into a pail

2.

Conductivity of contaminated sample was measured in room temperature.

3. Result was recorded in table 3.3

Result and Discussion:

In order to get the value of ESDD, first we have to get the value of resistivity (),

from the equation of:

=

= resistivity

= resistance

(Area of insulator) = 510.7052 cm2

(Length of the test cell) =80.1106 cm


22/25

21

Therefore, we can get the value of ESDD from equation:

=

_.43

65650 /.

(Area of testing insulator)

SAMPLE ADMITANCE(s) Resistivity () ESDD ( mg/cm2)

A 107 9345.79 0.012B 359 2785.52 0.041

C 590 1694.92 0.068

D 756 1322.75 0.088

Table 3.3

Table 3.3 above shows the value of ESDD as compared to each sample with

different level of contaminant. The value of ESDD increased as the number ofcontaminant is higher and the value varies between the range of 0.012 mg/cm2 and

0.088 mg/cm2.

As the objective of the experiment was to study the effect of contaminant

saturation towards insulation properties, the graph of ESDD versus capacitance was

plotted as shown in figure 3.2 below.


23/25

22

Figure 3.4 Relationship between ESDD and capacitance

From the graph, the result clearly shows that the value of capacitance increase

as the number of ESDD increased. The capacitance value of the sample become

bigger as the existence of contaminant is more.

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.1

48 50 52 54 56 58 60

ESDD(mg/cm2)

Capacitance (F)

Relationship Between ESDD and capacitance


24/25

23

CONCLUSION

In this experiment it is clearly shown that the contamination on the glass

insulator did effect the flash over voltage. The lower the contamination, the higher the

breakdown voltage. The dissipation factor are also effecting the efficiency of the

insulator. The higher the dissipation factor, the higher the leakage current. But, the

breakdown voltage will be lower. We cant avoid the contamination to be occurred

since its caused by nature, but we can actually have another alternative such as clean

the insulator especially at the sea area frequently which contain high contamination. An

automatic or controlled cleaner can be invented. Or we can also produce a better

insulator that can withstand a higher voltage such as ceramic insulator.


25/25

REFERENCES

http://composite.about.com/library/glossary/d/bldef-d1727.htm

http://en.wikipedia.org/wiki/Breakdown_voltage

http://scienceworld.wolfram.com/physics/Capacitance.html

http://www.princeton.edu/~achaney/tmve/wiki100k/docs/Transmission_line.html

http://www.thefreedictionary.com/flashover

http://www.wima.com/EN/dissipation.htm

http://www.wowhead.com/spell=137596/capacitance
http://composite.about.com/library/glossary/d/bldef-d1727.htmhttp://composite.about.com/library/glossary/d/bldef-d1727.htmhttp://en.wikipedia.org/wiki/Breakdown_voltagehttp://en.wikipedia.org/wiki/Breakdown_voltagehttp://scienceworld.wolfram.com/physics/Capacitance.htmlhttp://scienceworld.wolfram.com/physics/Capacitance.htmlhttp://www.princeton.edu/~achaney/tmve/wiki100k/docs/Transmission_line.htmlhttp://www.princeton.edu/~achaney/tmve/wiki100k/docs/Transmission_line.htmlhttp://www.thefreedictionary.com/flashoverhttp://www.thefreedictionary.com/flashoverhttp://www.wima.com/EN/dissipation.htmhttp://www.wima.com/EN/dissipation.htmhttp://www.wowhead.com/spell=137596/capacitancehttp://www.wowhead.com/spell=137596/capacitancehttp://www.wowhead.com/spell=137596/capacitancehttp://www.wima.com/EN/dissipation.htmhttp://www.thefreedictionary.com/flashoverhttp://www.princeton.edu/~achaney/tmve/wiki100k/docs/Transmission_line.htmlhttp://scienceworld.wolfram.com/physics/Capacitance.htmlhttp://en.wikipedia.org/wiki/Breakdown_voltagehttp://composite.about.com/library/glossary/d/bldef-d1727.htm

Documents

Ivat Lab Report. s4g4 (1)