Insulating Materials in Power Transformer.Pdf

بسمميحرلا نمحرلا هللا UNIVERSITY OF KHARTOUM FACULTY OF ENGNEERING DEPARTMENT OF ELECTRICAL AND ELECTRONIC ENGNEERING INSULATING MATERIALS IN POWER TRANSFORMERS By HUSSAM MAGID AHMED ABDALLAH INDEX NO.124041 Supervisor Dr. Alfadel Zakariya A REPORT SUBMITTED TO University Of Khartoum In partial fulfillment for the degree of B.Sc. (HONS) Electrical and Electronics Engineering (POWER SYSTEM ENGINEERING) Faculty of Engineering Department of Electrical and Electronics Engineering October 2017 DECLARATION OF ORGINALITY I declare this report entitled “(Insulating materials in power transformers)” is my own work except as cited in references. The report has been not accepted for any degree and it is not being submitted currently in candidature for any degree or other reward. Signature: ____________________ Name: _______________________ Date: ________________________ ii ACKNOWLEDGEMENT All the thanks, praises and glorifying is due to the Almighty GOD, without his uncountable blesses and uninterrupted gifts I wouldn„t be here a grown man about to graduate. To my mother, who grew me up, fed me, guided me through the life, many thanks and thanks. To my father who learnt me the patience and self-confidence. For my supervisor Dr.alfadel Zakariya, for his endless guiding and support. For my colleague, my partner in this project. iii Abstract There are many types of transformers insulators, some of them are used with conductors and the others are used to insulate the metal slides from each other and the others used to insulate the windings form the iron core. After collecting the parts of the transformer, it has to be dry enough because the insulators affected by the humidity which is make its isolation properties to be less than usual. In case of high internal temperature, transformer oil is considered one of the most important part of the cooling system, preventing the chemical interactions and detecting the faults e.i (short circuit) in a transformer. iv المستخلص ػٕاسل انًحٕﻻث نٓا إَاع كثٍزِ, بؼضٓا ٌسخخذو يغ انًٕصﻻث ٔانبؼض اﻻخز ٌسخخى نؼشل انشزائح انؼًذٍَت ػٍ بؼضٓا انبؼض ٔ يُٓا اٌضا يا ٌسخخذو فً ػشل انًهفاث ػٍ انقهب انحذٌذي. ػُذيا ٌخى جًغ انًحٕﻻث ٌجب حجفٍفّ فً افزاٌ خاصّ بذنك ﻻٌ انًٕاد انؼاسنّ فً انًحٕﻻث فً غانبٍخٓا حخأثز بانزطٕبّ يًا ٌؤدي انى َقصاٌ قابهٍّ انؼشل نذٌٓا. انحزارة انذاخهٍت فً انًحٕﻻث حسبب يشاكم كبٍزة فً حال حذٔثٓا نذا ؼٌخبز سٌج انًحٕﻻث يٍ اْى انؼُاصز انًسخخذيّ فً يُظٕيّ انخبزٌذ, ٌٔسخخذو انشٌج اٌضا فً ػشل انًهفاث ػٍ بؼضٓا انبؼض, ٔ بٍٍ انًهفاث ٔ انقهب ٔانخشاٌ انخارجً ,كًا ٌسخخذو فً يُغ انخفاػﻻث انكًٍٍائٍّ ػٍ طزق حغطٍّ اﻻجشاء انؼًذٍَّ, ٔاخٍزا ٌسخخذو انشٌج ككاشف نﻻػطال انخً قذ ححذد داخم انًحٕﻻث. v Table of Contents CHAPTER 1: Introduction ............................................................................................................. 1 1.1 Overview .......................................................................................................................... 1 1.2 Problem Statement ........................................................................................................... 1 1.3 Objectives ......................................................................................................................... 1 1.4 Methodology .................................................................................................................... 1 1.5 Thesis Layout ................................................................................................................... 2 CHAPTER 2: Literature Review .................................................................................................... 3 2.1 Power systems .................................................................................................................. 3 2.2 Transformers .................................................................................................................... 4 2.2.1 Introduction ...................................................................................................................... 4 2.2.2 Basic Working of Transformers ....................................................................................... 4 2.2.3 Equivalent circuit of transformer ..................................................................................... 5 2.2.4 Classification of Transformers ......................................................................................... 6 2.2.5 Types of Electrical Transformers ..................................................................................... 6 2.2.6 Basic Parts of a Transformer ............................................................................................ 8 2.2.7 Losses in Transformers .................................................................................................. 10 2.2.8 Testing of Transformers ................................................................................................. 12 2.3 Insulating materials used in transformers....................................................................... 16 CHAPTER 3: Methodology .......................................................................................................... 17 3.1 Overview ........................................................................................................................ 17 3.2 Case study ...................................................................................................................... 17 3.2.1 introduction .................................................................................................................... 17 vi 3.2.2 transformer insulation life .............................................................................................. 18 3.2.3 solid insulators ............................................................................................................... 18 3.2.4 transformer oil ................................................................................................................ 28 CHAPTER 4:Conclusion .............................................................................................................. 42 CHAPTER 5: Recommendation ................................................................................................... 43 vii Table of figures FIGURE 2-1 MAGNETIC CORE .......................................................................................................................................... 5 FIGURE 2-2 EQUIVALENT CIRCUIT .......................................................................................................................................... 6 FIGURE 2-3CIRCUIT DIAGRAM FOR OPEN CIRCUIT TEST ............................................................................................................ 15 FIGURE 2-4 CIRCUIT DIAGRAM FOR SHORT CIRCUIT TEST ........................................................................................................... 17 FIGURE 3-1 THE SCHEMA ILLUSTRATING THE SAMPLE PREPARATION PROCEDURE ........................................................................... 21 FIGURE 3-2 THE RELATIVE PERMITTIVITY OF KRAFT PAPER AND POLYPROPYLENE IMPREGNATED .............................. 23 FIGURE 3-3 THE LOSS TANGENT AT 1000 HZ AS A FUNCTION OF TEMPERATURE FOR ................................................. 23 FIGURE 3-4 THE BREAKDOWN STATISTICS OF PRISTINE PAPER. THE DATA ARE ANALYZED ........................................... 25 FIGURE 3-5 THE BREAKDOWN STATISTICS OF PP IMPREGNATED PAPER. THE DATA ARE ............................................... 25 FIGURE 3-6 FABRE-PICHON CURVES FOR MOISTURE EQUILIBRIUM OF THE AIR-OIL-PAPER COMPLEX AS A FUNCTION OF THE AIR AND OIL SURROUNDING THE PAPER. FIGURE IS TAKEN FROM [Z] EXCEPT LABELS ARE TRANSLATED INTO ENGLISH. ............................................................................................................................................................ 27 FIGURE 3-8 OOMMEN‟S CURVES FOR MOISTURE EQUILIBRIUM FOR A PAPER-OIL SYSTEM ............................................ 28 FIGURE 3-9 MOISTURE IN WOOD PULP AS A FUNCTION OF RELATIVE HUMIDITY OF THE AMBIENT BELFRIES .PICTURE SUPPLIED BY OOMMEN AT ABB-ET1 WHO REDREW JEFFRIES‟ DATA. ................................................................ 29 FIGURE 3-10 MOISTURE IN PAPER VERSUS AMBIENT RELATIVE HUMIDITY CURVES COMPARING ........................................................ 30 FIGURE 3-11GRIFFIN CURVES FOR WATER EQUILIBRIUM IN CELLULOSE MINERAL OIL SYSTEMS .......................................................... 30 FIGURE 3-12 MIT-DEVELOPED CURVES FOR WATER EQUILIBRIUM IN CELLULOSE MINERAL OIL SYSTEMS FOR A WIDE RANGE OF MOISTURE CONCENTRATIONS ............................................................................................................. 31 viii CHAPTER 1: Introduction 1.1 Overview: The life of a power transformer is limited to the life of its solid and liquid insulation, many diagnostic techniques and tests are used to prolong the service life of the power transformer and to insure that the transformer will operate in an efficient, effective and high quality functional life. These tests and techniques will be stated in detail in the next chapters 1.2 Problem statement: Damaging of a power transformer due to external or internal faults and the part played by the insulation materials to prevent these damages Understanding and perception the Tests and techniques performed on the soiled and liquid insulation materials 1.3 Objectives: Better determination and perfect choice of a power transformer with high Specifications

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