Techniques for Detecting Paper Degradation in Large Power Transformers
CHAPTER 1 INTRODUCTION
Power transformers are very important in the electrical power sector; they are among the expensive assets of power generation and distribution systems. .
According to Piush Verma [16], transformers are static electromagnetic devices consisting of two or more windings which are linked with a common magnetic field used for the distribution of electrical power from one voltage level to another. Some of the main parts of the transformer are; the windings, tank and insulation (solid or liquid).
Transformers normally have an operating temperature range of 60-90oC and an operation lifetime of 40 years [8]. These service temperatures cause gradual degradation of the oil and paper insulation thereby producing degradation by-products such as furans, CO2, CO and water [8].
For reliable operation of transformers, it is therefore important to embark on effective maintenance strategies using various degradation sensing techniques such as the furan analysis and infrared spectroscopy, aiming at identifying the change in properties and concentrations of these by-products associated with the degradation of transformer insulation. Predictions of such problems make the removal of the transformer from service possible before its insulation deteriorates to avoid catastrophic failures or extend the service life of the transformer.
This report therefore attempts to examine methods for detecting paper degradation in large power transformers and suggest future trends in this field.
CHAPTER 2
PAPER INSULATION
Insulation is provided by a material that reduces the flow of heat or electricity. The material can be adapted to any form and it is diverse in properties and
Power transformers are very important in the electrical power sector; they are among the expensive assets of power generation and distribution systems. .
According to Piush Verma [16], transformers are static electromagnetic devices consisting of two or more windings which are linked with a common magnetic field used for the distribution of electrical power from one voltage level to another. Some of the main parts of the transformer are; the windings, tank and insulation (solid or liquid).
Transformers normally have an operating temperature range of 60-90oC and an operation lifetime of 40 years [8]. These service temperatures cause gradual degradation of the oil and paper insulation thereby producing degradation by-products such as furans, CO2, CO and water [8].
For reliable operation of transformers, it is therefore important to embark on effective maintenance strategies using various degradation sensing techniques such as the furan analysis and infrared spectroscopy, aiming at identifying the change in properties and concentrations of these by-products associated with the degradation of transformer insulation. Predictions of such problems make the removal of the transformer from service possible before its insulation deteriorates to avoid catastrophic failures or extend the service life of the transformer.
This report therefore attempts to examine methods for detecting paper degradation in large power transformers and suggest future trends in this field.
CHAPTER 2
PAPER INSULATION
Insulation is provided by a material that reduces the flow of heat or electricity. The material can be adapted to any form and it is diverse in properties and
References: [3] Blue, R., Uttamchandi, D., and Farish, O., “Infrared detection of transformer insulation due to accelerated aging” IEEE transactions on dielectrics and electrical insulation, Vol.5, No.2, (1998). [4] Carloso, A.J.M., and Oliveira, L.M.R., “Condition monitoring and diagnostics of power transformers”. Int.J. COMADEM, Sunderland, U.K., Pp. 5-11., (1999). [5] Christofidis, S., “Analytical methods for assessing paper degradation in transformers”: thesis submitted in partial fulfilment of the requirements for the degree of master of research in electrical engineering. Cranfield University., (2006). [18] Xianyang, L., Fangjie, Z., Fenglei, H., “Research on on-line DGA using FT-IR [power transformer insulation testing]”. Proceedings of POWCON international conference on power system technology, Vol.3, (2002) [19] Copper development association Inc [24] Cambridge viscosity, no date, “Degree of polymerisation measurement equipment, [on-line photograph]” Available from http://www.cambridgeviscometer.com/laboratory-viscometers [Assessed on 5 march, 2012]