JURUSAN TEKNIK ELEKTRO

FAKULTAS TEKNOLOGI INDUSTRI

UNIVERSITAS BUNG HATTA

PROPOSAL SKRIPSI

Nama : SYARBAINI NUR

No. BP : 0910017111058

Peminatan :

Judul Skripsi : INVESTIGASI PENYEBAB KENAIKAN SUHU PADA

TERMINASI KABEL OKONITE DENGAN PEMANFAATAN

KAMERA INFRAMERAH (THERMACAM)

Pembimbing 1 :

Pembimbing 2 :

Dilaksanakan :

Duri, 25 April 2010

Di Usulkan Oleh,

( SYARBAINI NUR )

Mengetahui :

Pembimbing I,

--------------------

Mengetahui :

Pembimbing II,

--------------------

Koordinator Skripsi,

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1. INVESTIGASI PENYEBAB KENAIKAN SUHU PADA TERMINASI KABEL

OKONITE DENGAN PEMANFAATAN KAMERA INFRAMERAH

(THERMACAM)

2. ABSTRAK

Dalam dunia industri, salah satu jenis industrial fault yang sering terjadi adalah

munculnya Hot Spot (titik panas) pada instalasi listrik yang menjadi penghubung antar

konduktor, baik itu antara kabel ke busbar, kabel ke kabel, ataupun kabel ke terminal

lainnya, dll. Gejala pemanasan yang terjadi ini bisa di sebabkan berbagai jenis

permasalahan, dan umumnya suatu peralatan memasuki tahapan mengeluarkan panas

yang berlebihan sebelum kerusakan phisik muncul. Kerusakan phisik yang terjadi ini

bisa berupa kerusakan pada isolator kabel, kerusakan sambungan, ketidakseimbangan

arus, atau bahkan bisa mengakibatkan terjadinya arc flash yang dapat menjadi pemicu

terjadinya kebakaran. Untuk membantu mengurangi terjadinya kasus seperti tersebut

penulis bermaksud untuk mempelajari penyebab yang mungkin menjadi sumber

pemicu munculnya hotspot. Dengan memanfaatkan teknologi infrared thermography

penulis mencoba menyingkap hal-hal yang memiliki potensi sebagai penyebab

munculnya hotspot yang terjadi. Dengan harapan hal ini bisa membantu kehandalan

instalasi listrik pada dunia industri, membantu menunjukkan pada dunia kelistrikan

akan hal-hal yang patut diperhitungkan dalam menjaga kehandalan suatu fasilitas

kelistrikan, sehingga instalasi listrik yang dipergunakan memiliki tingkat keamanan

dan kehandalan yang lebih baik, mengurangi terjadinya breakdown, dan cost saving

yang optimal.

Index Term : Hotspot, ThermaCam, Terminasi

3. LATAR BELAKANG

Pemakaian konduktor listrik adalah mutlak dalam dunia industri. Baik itu berupa

kabel, kawat, busbar, batangan atau bahkan pelat logam. Saat transmisi listrik,

konduktor yang di gunakan menanggung dua jenis beban, yaitu beban arus yang

melewatinya dan beban panas sebagai akibat negatif dari besarnya arus listrik yang

lewat. Banyak cara yang di tempuh dalam dunia industri untuk menekan efek negatif

arus listrik yang berupa panas ini. Baik dengan memilih material yang memiliki daya

tahan panas tinggi, ataupun dengan menggunakan mesin pendingin seperti Air

conditioner, dll. Namun hotspot tetap bisa muncul dalam operasionalnya.

Gbr 1. Salah satu kasus hotspot pada terminasi kontaktor

Seperti halnya industri lainnya, PT. Chevron Pacific Indonesia juga mengahadapi

tantangan yang sama, pada instalasi listrik yang di pergunakan. Terutama pada instalasi

listrik 3-Phasa. Karena secara umum beban untuk listrik 3-phasa lebih besar dari pada

beban listrik yang 1-phasa., sehingga konsumsi arusnya juga besar. Sebagai

kompensasinya tentu saja panas yang muncul akan lebih tinggi. Sebagai efek dari

terjadinya hotspot tersebut, sebagian dari kabel tersebut mengalami kerusakan pada

isolatornya. Kerusakan terbanyak terjadi pada isolator ujung-ujung kabel, dan berawal

dari titik-titik terminasi kabel. Bahkan ada kabel yang terbakar habis bersamaan

dengan melelehnya terminasinya, karena hotspot yang terjadi sangatlah tinggi. Untuk

meminimalisasi munculnya kasus-kasus seperti ini, maka penulis mencoba untuk

menganalisa penyebab kegagalan awal pada terminasi kabel yang menjadi faktor

penyebab kenaikan suhu pada terminsasi instalasi listrik yang di pergunakan.

4. DEFINISI MASALAH

Studi pengkajian skripsi diarahkan pada permasalahan:

1. Mengamati kondisi yang menjadi penyebab kenaikan suhu pada terminasi kabel.

2. Mengamati kondisi hotspot yang terjadi dan menganalisa penyebabnya dengan

memanfaatkan kamera inframerah.

3. Menentukan parameter-parameter penyebab kenaikan suhu pada terminasi kabel .

5. BATASAN MASALAH

Dalam pengerjaan skripsi ini permasalahan akan dibatasi pada hal:

Terminasi kabel yang dipilih adalah terminasi kabel listrik 3-phasa yang memiliki

tegangan operasional 460 V s/d 500 V.

Tidak membahas tentang pengaruh kimiawi terhadap terminasi.

6. METODA PENELITIAN

Langkah-langkah dalam penelitian yang akan dilakukan penulis meliputi:

Studi literatur

Studi Literatur yang dilakukan, disini penulis mencoba mengumpulkan data

tentang kabel yang digunakan yaitu jenis OKONITE khusus untuk Tray Aplication.

Data yang dikumpulkan akan mengarah ke arah kemampuan kabel sebagai

penghantar arus, dan kemampuan isolatornya sebagai pembatas tegangan tembus

dan suhu.

Hal lain yang akan di pelajari penulis mengarah ke kamera inframerah

(ThermaCam) yang di gunakan. Prinsip dasar ThermaCam, parameter-parameter

penting yang mempengaruhi pemakaian ThermaCam, dan batasan kemampuannya.

Pengumpulan dan Pengolahan Data:

Penulis akan mengumpulkan data kasus-kasus munculnya hotspot yang terjadi pada

instalasi listrik yang digunakan, khususnya mengarah hotspot yang muncul pada

terminasi kabel OKONITE yang digunakan. Metode Instalasi yang di terapkan

dilapangan, untuk spesifikasi unit yang sama, akan dilihat metode instalasi yang

diterapkan.

Data yang ada ini akan dikelompokkan berdasarkan beban yang dipakai, area

tempat pengambilan data, dan persamaan instalasi yang diterapkan.

Experimen Pengamatan

Pada tahapan ini penulis melakukan riset apa saja yang menjadi titik awal

munculnya hotspot yang terjadi berdasarkan data yang di ambil. Penulis juga

melakukan perbaikan terhadap kejadian hotspot yang muncul, untuk melihat

apakah kasus yang sama akan berulang lagi atau tidak. Hasil percobaan, perbaikan,

dan pengamatan ini akan menjadi masukan bagi penulis untuk mendata parameter-

parametr apa saja yang menjadi penyebab hotspot pada terminasi kabel, parameter-

parameter pendukung yang menjadi pemicu kemungkinan terjadinya tingkat

kerusakan yang lebih tinggi, dan parameter-parametr luar yang mungkin menjadi

katalis terjadinya hotspot tersebut.

Pengamatan yang dilakukan penulis ruang lingkupnya meliputi kondisi lingkungan,

jenis beban yang digunakan, teknik instalasi yang diterapkan, dan hal-hal lain yang

mungkin menjadi faktor penyebab munculnya hotspot tersebut.

Data yang sudah ada akan diolah dengan bantuan software khusus yang menjadi

alat pendukung utama dalam menganalisa kasus yang terjadi.

7. TINJAUAN PUSTAKA

Pada penelitian ini penulis telah memeriksa beberapa tulisan yang memiliki

hubungan dengan pengamatan yang penulis lakukan, antara lain:

A. Haas1* and J. Kindersberger1 (DETERMINATION OF AGEING OF

POLYMERIC INSULATING MATERIALS BY THERMAL ANALYSIS

METHODS) 1 Lehrstuhl für Hochspannungs- und Anlagentechnik, TU München,

Germany. *Email: alexander.haas@tum.de

Abstract:

In this paper Differential Scanning Calorimetry (DSC) and Thermogravimetrical

Analysis (TGA) are used to evaluate different kinds of ageing phenomena in

polymeric insulating materials. Specimen of different polymer insulating materials

(cross-linked Polyolefin, ETFE and silicone rubber) with a defined preconditioning

are subject to a DSC and a TGA, identifying parameters such as glass transition,

melting temperature and degree of cross-linking and crystallisation. The samples

subsequently undergo a certain treatment in form of thermal ageing or storage in

hot salty water and by voltage stress. In the following, another analysis is being

performed. Differences in the measured curves of new and aged samples give

information about modifications in the polymer due to ageing. By the applied

methods it is possible to identify physical ageing such as inclusion of water and

chemical ageing such as cracking of polymer chains.

Zdena Benešová, Martin Škopek, Bohuš Ulrych and Ivo Doležel, Member, IEEE

( Investigation of Electric Stress of Insulation of a Three-Phase Power Cable

with Respecting its Heating by Passing Currents )

Abstract –

The paper is aimed at determination of the electric stress of insulation of a three-

phase cable and check of its dielectric strength. The task is formulated as a

combined electro-thermal problem. The steady-state temperature field is calculated

from the Joule losses produced by the currents passing through the conductors and

other metal parts of the cable. Solution to the problem is carried out numerically,

by means of the FEM-based programs. The theoretical analysis is supplemented by

an illustrative example and discussion of the results.

I. INTRODUCTION

Transmission of the electric energy by power cables results in growth of their

temperature, which can negatively affect quality of their insulation and cause za

substantial decrease of its lifetime [3]. The reason consists in two antagonistic

trends: the tendency of transmitting currents as high as possible and, on the other

hand, to prevent the temperature rise of the cable from exceeding the admissible

value. Operation accompanied by such undesirable effects may occur at long-term

- load of the cable by the nominal current or voltage,

- overload of the cable by higher currents or voltages (that must not, however,

exceed certain values given as multiples of the nominal load).

Quantitative answers to different questions associated with these problems may be

obtained from suitable experiments or - much more operatively and (based on the

contemporary theoretical knowledge) substantially reliably - from the computer

modelling. This possibility is also used in the presented paper that deals with the

numerical solution of the electric stress of insulation of a three-phase cable NYFY

1 kV [1] in both above cases of the long-term load. Its resultant values are then

compared with the dielectric strength of the insulation, which is a function of the

temperature (that depends on the operation regime of the cable, particularly on the

passing currents).

The solution starts from formulation of the particular technical problem and its

mathematical model, that is given by equations describing the

- steady state temperature field distribution within the cross-section of the cable,

- time-dependent distribution of the electric field.

The model is then solved by the FEM-based professional program QuickField [2]

supplemented by special user programs.

Except for the methodology of computation the paper presents the most important

results of a typical illustrative example and discussion of its results. Discussed are

also possibilities of further possible improvements of the described algorithm

consisting in its hard-coupled formulation, that would enable to respect continuous

variations of the electric resistance of the cable in dependence on its temperature

rise.

8. RENCANA PENELITIAN

Pada Rencana penelitian ini, penulis akan meneliti secara langsung kesesuaian

dilapangan di bandingkan dengan teori berikut:

In the present study the performance of low-voltage polymer-insulated cables for

application in harsh environmental conditions is investigated. Temperatures up to

423 K (150°C) and saline water immersion may occur during application. The

range of applied AC and DC voltage is up to 1 kV. For the given environmental

conditions no knowledge of the specific ageing of the insulating materials is

available. Therefore, the ageing of the polymeric insulation due to the expected

stresses is investigated in detail in this study. The focus is set on the ageing

mechanism effecting the polymer structure and chemistry, since these are the cause

for any decrease in the electric performance. In future investigations, the detected

phenomena of polymer ageing will be compared to the electric performance of the

aged cables.

2. AGEING MECHANISM

Ageing can be classified in two groups: Physical ageing is a reversible, temporary

reduction of properties which disappears with the removal of the influencing factor

(defined as degradation [1]). On the contrary, chemical ageing causes an

irreversible, permanent reduction of properties (defined as deterioration [1]).

Regardless of the formal definition the term degradation is commonly used for all

kinds of ageing mechanism and shall thus be used in the same way in this study.

2.1. Chemical Ageing

All chemical ageing phenomena involve a chemical polymer reaction whereas.

Chemical ageing can be initiated by temperature alone, by water or other fluids, by

particle and ultraviolet radiation and some more [4]. In the following we will

concentrate on the phenomena most characteristic in the present investigation.

Thermal degradation follows the free radicals mechanism, initiated by oxygen or

oxidative contamination in the material [10] or other stresses [4]. Depending on

the polymer the thermal activation of reactions can lead to [10]:

depolymerisation of the main chain starting at the end of the chain

statistical chain break, which may result in

depolymerisation from resolving ends

radical transfer and disproportionation

stabilisation of fragments

break of side groups

inter-chain condensation and splitting of small molecules

Usually this type of degradation results in mainly the monomer and a mix of

oligomeres, cycled or linear, and a variety of by-products. The main reaction, the

free radicals mechanism, can be characterised by steps of initiation, radical

preserving reactions and radical recombinations [5].

The path taken through the numerous possibilities of reactions is highly dependent

on ambient conditions and the polymer itself. Oxidative reaction is equally a

degradation process based on free radicals, which consists of steps of initiation,

propagation and termination. The mechanism depends on peroxy radicals [5]. Like

simple thermal degradation, oxidative reactions may lead to breaking of the main

chain as well as crosslinking between chains. This generally results in the

monomer itself, additionally various oxidative compounds can be formed this way

Some additive materials are capable of catalyzing an oxidative reaction of

polymers, such being copper and copper oxide [9].

Hydrolysis is, unlike thermal or oxidative degradation, an ion reaction, leading to

random scissions of macromolecules. It may not occur in all kinds of polymers.

Most vulnerable to hydrolysis attacks are ester linkages [4], which appear

especially in Polyester and epoxy resin, but also in some silicone rubber

compounds. The dependence of this reaction on the presence of vulnerable linkages

in the polymer gives the varying sensitivity of polymers to this reaction.

Hydrolysis in theory is a reversible reaction [6]. In practice the reverse reaction

requires diffusion of large macromolecules which may slow the back esterification

to an insignificant level [7].

2.2. Physical Ageing

In contrary to chemical ageing the physical ageing process does not modify the

chemical structure of the polymer. However, due to physical ageing mechanism

significant changes in material properties can be observed.

The processes which carry physical ageing can be [2]:

- alteration in molecular order and crystallisation pattern

- diffusion of gases and fluids (including water) into the polymer

- evaporation of additives such as plasticisers or flame prohibiter.

Most of these phenomena are regarded to be reversible, excluding of course the

evaporation of additives. Thus an electrical insulation, which has been immersed in

water, may regain its original properties after complete drying as long as no

hydrolytic deterioration has occurred. The crystallisation pattern of a semi

crystalline polymer in its new condition is – either by purpose or by chance –

dominated by manufacturing temperatures or thermal treatment during the

production process.

Every thermal storage alters the thermal history of the polymer and thus its

crystallisation pattern. This physical ageing effect may influence the chemical

ageing as well, since active gas particle diffusion is sensitive to the crystallinity of

the polymer [8].

3. EXPERIMENTAL

3.1. Water Storage Setup

The setup for ageing by salt water storage in combination with voltage stress is

shown in Figure 1. Cable specimen with a length of (2500 ± 50) mm were prepared

by removing the insulation of both ends of the cable and closely winding three

complete turns on a mandrel with a diameter of 10 cm. The cables were immersed

by a length l of 2 m in a 3% sodium chloride (NaCl) solution with the ends

protruding approx. 250 mm from the liquid. Grounded guard electrodes made of

copper tape were fixed at a distance from the open ends to prevent surface

currents. One end of the cable was connected to a high precision 500 V DC source

and the complete test setup was stored in a heating cabinet at various

temperatures. The measurement electrode was immersed into the saline solution

and connected to a Keithley pA-meter with 10 fA resolution. The volume resistivity

of the cable insulation can thus be calculated as follows:

3.2. Thermal Storage Setup

Storage of cable specimen at high temperatures was carried out in a furnace

according to ISO 6722. The test samples had a minimum length of 350 mm each.

The test samples were fixed by the conductor to avoid any contact between the

insulation and the supports and were separated by at least 20 mm from each other

and from the inner walls of the oven.

Two groups of specimens were tested at different storage durations and

temperatures. The first group was kept for 240 hours at a temperature of 473 K

(200°C), the second group for 6 hours at 498 K (225°C).

3.3. Simultaneous Thermal Analysis

Apparatus: The apparatus used for thermal analysis is a Linseis STA, a

combination of Differential Scanning Calorimetry (DSC) and a

Thermogravimetrical Analyser (TGA). The system consists of a heating unit which

contains the specimen on a high precision balance. Additionally, the specimen is

placed upon a thermocouple, which detects the temperature of the sample in

comparison to an empty sample carrier. The heating unit can operate at a thermal

range from liquid nitrogen up to 1000 K. The sample weight is logged with 0.5 µg

accuracy, the heat flux with 0.3 µW. The specimen mass was 13 mg for all samples.

The chamber of the heating unit has continuously been flushed with Nitrogen

during the complete measuring procedures.

A two-step heating cycle is performed on all samples (Figure 2). The initial cooling

is followed by the first heating run with 10 K/min from 173 K (-100°C) up to 473 K

(200°C) for PO-X and silicone rubber and 573 K (300°C) for ETFE. A second

cooling period with -5 K/min gives the defined thermal history for the following

second heating run, which goes up to 1000 K (≈ 700°C) by a rate of 10 K/min. In

addition, to exclude influences from the first heating run on the TG results, a

separate TG analysis with another sample of the same material was performed

starting from room temperature up to 1000 K by a rate of 10 K/min.

In general, a DSC analysis consists of two heating runs. The curve of the first

heating run is dominated by the thermal and mechanical history of the tested

material and the curve of the second heating run gives information about material

characteristics. Focused on the detection of ageing effects, physical ageing can be

detected in a DSC by various differences between the measurement curves of new

and aged samples [2]:

The first heating run of the aged sample indicates a higher melting peak

temperature and higher crystallinity than the first heating run of the new sample

In the second heating runs of new and aged sample no difference can be observed

Chemical ageing in turn can be detected in a DSC as follows:

- The first heating runs of new and aged sample indicate differences in

melting peak temperature and crystallinity

- The second heating run of the aged sample indicates reduced crystallinity

and a lower peak temperature

9. SUMBER YANG DIPERLUKAN

Untuk kelancaran proses analisis maka diperlukan data – data yang lengkap dan

benar supaya tidak terjadi kesalahan yang tidak diinginkan. Untuk penelitian ini

yang diperlukan adalah data – data seperti : hasil pengambilan gambar dari kamera

inframerah, electrical circuit diagram dari instalasi listrik yang diambil, hasil

inspeksi temperature dan arus saat operasional, dan software khusus untuk

mengolah dan menganalisa gambar thermacam yang sudah di ambil tersebut.

Penulis juga membutuhkan data berapa unit yang mengalami munculnya hotspot

dalam setahun. Di sini penulis akan mencoba membandingkan dengan data pada

tahun berikutnya. Sehingga akan terlihat suatu perubahan atau tidak.

Data-data mengenai infrastruktur secara kelistrikan juga akan sangat menunjang

kegiatan penulis. Terutama sekali data kabel jenis OKONITE type Tray

Application yang di gunakan pada setiap unit yang akan di amati penulis.

10. JADWAL KEGIATAN

KEGIATAN BULAN 1 BULAN 2 BULAN 3 BULAN 4

Studi Literatur X X

Pengumpulan Data X X

Pengolahan Data X X

Analisa Data X X X

Penulisan X X X X

Penyerahan X

11. RINGKASAN

Tujuan yang ingin dicapai dalam Skripsi ini adalah:

Mendapatkan parameter apa saja yang menyebabkan kenaikan suhu pada terminasi

kabel sehingga pengaruh negatif terhadap isolator kabel bisa di kurangi

Mendapatkan metode pencegahan untuk meminimalisir terjadinya hotspot pada

terminasi kabel.

Hasil yang diperoleh dari skripsi ini diharapkan dapat memberi manfaat sebagai

berikut:

Menjadi referensi dalam operasi kabel listrik

Menjadi bahan pertimbangan teknis untuk mengurangi kerusakan isolator kabel

power 3-phase.

12. DAFTAR PUSTAKA

Wire & Cable – Electrical Manual – Chevron Corporation

Internet

Investigation of Electric Stress of Insulation of a Three-Phase Power Cable with

Respecting its Heating by Passing Currents (2000) - Zdena Benešová, Martin

Škopek, Bohuš Ulrych and Ivo Doležel, Member, IEEE

DETERMINATION OF AGEING OF POLYMERIC INSULATING

MATERIALS BY THERMAL ANALYSIS METHODS (2009) A. Haas1* and

J. Kindersberger1 1 Lehrstuhl für Hochspannungs- und Anlagentechnik, TU

München, Germany