Interaction mechanisms of natural ester dielectric fluid and Kraft paper

Sealed tube accelerated aging studies demonstrate a slower aging rate for cellulose insulation in natural (vegetable oil) ester dielectric fluid compared to the rate in conventional transformer oil. The interactions of natural ester fluid and cellulose insulation resulting in increased paper life are described by two interrelated chemical reaction mechanisms. Compared to the conventional transformer oil/Kraft paper system, the natural ester fluid's greater affinity for water shifts more water from the paper into the fluid in order to maintain equilibrium. The natural ester fluid reacts via the primary mechanism of hydrolysis to consume dissolved water in the fluid, shifting further the paper/fluid equilibrium to further dry the paper and produce free fatty acids. These fatty acids serve as reactants in the secondary mechanism of transesterification to modify the cellulose structure. The change in cellulose structure is verified using infrared analysis.

[1]  Charles Q. Yang,et al.  Applications of FT-IR spectroscopy to the studies of esterification and crosslinking of cellulose by polycarboxylic acids: Part I. Formation of cyclic anhydrides as the reactive intermediates , 1998 .

[2]  J. Luksich.  Aging of Cotton/Kraft Blend Insulation Paper in Natural Ester Dielectric Fluid , 2003 .

[3]  C. McShane,et al.  Fire resistant natural ester dielectric fluid and novel insulation system for its use , 1999, 1999 IEEE Transmission and Distribution Conference (Cat. No. 99CH36333).

[4]  C.P. McShane,et al.  Aging of paper insulation retrofilled with natural ester dielectric fluid , 2003, 2003 Annual Report Conference on Electrical Insulation and Dielectric Phenomena.

[5]  C. Vaca-Garcia,et al.  Solvent-free fatty acylation of cellulose and lignocellulosic wastes. Part 2: reactions with fatty acids , 1999 .

[6]  C.P. McShane,et al.  Aging of paper insulation in natural ester dielectric fluid , 2001, 2001 IEEE/PES Transmission and Distribution Conference and Exposition. Developing New Perspectives (Cat. No.01CH37294).

[7]  W. Glasser,et al.  Long-Chain Cellulose Esters: Preparation, Properties, and Perspective , 1998 .

[8]  B. Tao,et al.  Synthesis and characterization of long‐chain fatty acid cellulose ester (FACE) , 1994 .

[9]  H. S. Kwatra,et al.  Synthesis of long chain fatty acids esterified onto cellulose via the vacuum-acid chloride process , 1992 .

[10]  Ieee Standards Board.  IEEE guide for acceptance and maintenance of insulating oil in equipment , 1992 .

[11]  A. Buléon,et al.  Acidic activation of cellulose and its esterification by long‐chain fatty acid , 1999 .

[12]  L. Yong.  Study on Electrical Aging Lifetime of Vegetable Oil-paper Insulation , 2007 .

[13]  T. Edison,et al.  Aging of Kraft Paper in Natural Ester Dielectric Fluid , 2002 .

[14]  Earl L. Morrison.  Evaluation of the Thermal Stability of Electrical Insulating Paper , 1968, IEEE Transactions on Electrical Insulation.