الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
 |  | from | 119 |  |  |
| | | from | 119 | | |
Abstract
Vegetable based oils as dielectric fluids find growing acceptance and application in electric equipments as liquid insulator allover the world. They are considered as suitable fluids in accordance with the concept of saving resources and using renewable resources. Turning to renewable environmental friendly insulating fluids in power and distribution transformers became a must because the dependence on the conventional depleting mineral oil put the users in critical situation. So many companies search for natural ester benefits as a substituent of mineral oils. There are many examples produced and performed in the electric market. The aim of this study is to find a local available environmental friendly insulating fluid instead of mineral oil.
In this part, eight vegetable oils were converted into methyl esters via transesterification process to improve their physical and chemical properties. Natural esters are very hygroscopic i.e. they absorb water rapidly and with large quantities which cause them fail to face oxidation. This may lead to failure of their electrical, chemical and physical tests.
Each ester produced was divided into 2 parts: The first part was tested as dielectric fluid according to ASTM methods and the results are compared with International Standard Specifications (International Electrotechnical Commission IEC). The second part was treated with DBPC (2,6-di-tert-butyl-p-cresol) as an antioxidant additive and then tested as dielectric fluid according to ASTM methods. The results obtained were compared with IEC specifications again.
Part ІІ: STUDIES ON THE USE OF VEGETABLE BASED POLYESTERS AS DIELECTRIC INSULATING FLUIDS IN ELECTRIC EQUIPMENTS
In this part, four vegetable oils namely: linseed, rapeseed, radish and used frying oil were subjected to two successive transesterification processes. Firstly, these oils were converted into the methyl esters which were further transesterified using pentaerythritol to give the corresponding polyesters.
Each polyester produced was divided into 2 parts: the first part was tested as dielectric fluid according to (American Society for Testing and Materials ASTM) methods and the results were compared with International Standard Specifications (International Electrotechnical Commission IEC). The second part was treated with DBPC (2,6-di-tert-butyl-p-cresol) as an antioxidant additive and then tested as dielectric fluid according to ASTM methods and the results were compared with IEC specifications again. Linseed polyester and used frying oil polyester gave better results.
Part ІІІ : A FIELD STUDY: THE USE OF THE POLYESTER OBTAINED from THE USED FRYING OIL AS INSULATOR IN A MODULE OF POWER TRANSFORMER.
In this part, the polyester obtained from the used frying oil was utilized as an insulating fluid in a module of power transformer. The selection of this polyester is based on: (i) it gave better results than the other tested polyesters (cf. part II)., (ii) the used frying oil has negligible cost., (iii) being undesired waste, the use of it represents a benefit of recycling process.
The polyester of used frying oil prepared was treated with DBPC (2,6-di-tert-butyl-p-cresol) 2% w/w and a simple module of transformer was filled with it. Then the module was put under normal operation conditions for a period of one month. The insulating liquid was tested again after aging circumstances. The results obtained were found to be satisfactory and reliable compared with the IEC standards.