How water affects transformer oil quality and helps monitor its aging

This article attempts to explain not only how moisture affects the quality of the insulating liquid, but also how online sensing of moisture parameters can be used in continuous monitoring of oil condition, rate of oil deterioration and aging of both oil and paper insulation, because, apart from being an insulator and a coolant, oil is also an information carrier

Water in transformers

The idea to write a Q&A column about water in transformers for this magazine came from various speaking and consulting engagements. Very often during seminars, workshops or technical presentations I have been asked to explain and elaborate on ‘seems to be trivial’, but ‘appeared to be’ complex phenomena, statements or a fact related to presence and effects of water in transformers. Water in transformers is an intriguing topic and usually attracts an interest of large groups of professionals in the field of high-voltage electrical equipment operation and maintenance. From the onset of transformer manufacture, drying of solid and liquid insulation presents an operational and technical challenge, consuming a lot of effort and resources. Even after a thorough job on drying, water finds its way into a transformer taking every possible path during its transportation from factory floor to the final destination. Water is often labelled as the worst enemy of transformers and numerous research papers have been published covering this uneasy subject. Water is the source of all life on our planet, but in transformers, this is one of the major life-threatening substance. Here comes the first question

Water in transformers: Moisture equilibrium in transformer insulation systems: Mirage or reality? Part 1

In the operating transformer water is always in transition, either moving within cellulose insulation or migrating from paper to oil and versa visa. This article introduces a methodology where we use an equilibrium chart for an assessment of a dynamic process which may not reach an equilibrium and still give us a good sense of moisture state in the oil/paper system

Infected Cell Protein No. 22 Is Subject to Proteolytic Cleavage by Caspases Activated by a Mutant That Induces Apoptosis

AbstractEarlier reports have shown that the d120 mutant of herpes simplex virus 1 lacking both copies of the gene encoding the infected cells protein No. 4 (ICP4) induces apoptosis in a variety of cell lines. The programmed cell death induced by this mutant is blocked by overexpression of Bcl-2 or by transduction of infected cells with the gene encoding the viral US3 protein kinase. HEp-2 cells infected with the d120 mutant express predominantly α proteins. Studies on these proteins revealed the accumulation of a Mr 37,500 protein that reacted with antibody directed against the carboxyl-terminal domain of ICP22. We report that the Mr 37,500 protein is a product of the proteolytic cleavage of ICP22 by a caspase activated by the d120 mutant. Thus the accumulation of the Mr 37,500 protein was blocked in cells transduced with the US3 protein kinase, in cells overexpressing Bcl-2, or in infected cells treated with the general caspase inhibitor zVAD-fmk. Exposure of ICP22 made in wild-type virus-infected cells to caspase 3 yielded two polypeptides, of which one could not be differentiated from the Mr 37,500 protein with respect to electrophoretic mobility. We conclude that the cellular apoptotic response targets at least one viral protein for destruction