Behavior of transformer insulation under short-time overvoltage
This paper reports on a series of tests made on transformer insulation samples with automatically applied short-time a.c. overvoltages above the corona inception level to determine the conditions under which damaging corona occurs. Modified dielectric tests for power transformers are discussed.
A bibliographic review of trends in design and management of electrical power transmission transformers
Electricity transmission substations are fixed infrastructure assets, and the power transformer is the most visible item of equipment. The technologies embedded in protection and control switchgear, as well as in power transformers change over the very long life of a substation, even though the basic functionality remains the same. Changes in equipment technologies present salient but real challenges in design of electricity transmission networks, and especially on acquisition, operation and maintenance, and disposal of transformers deployed in substations. In addition to obsolescence, some of the challenges include age-related degradation, as well as increasingly sophisticated loading requirements on substations. A bibliographic search between 1970 and 2014 indicates that new materials plus computer-aided modelling and tools are widely applied to design and manufacture transformers to achieve higher voltage and power ratings, while sensors, information and computing systems technologies and big data analytics are increasing applied to determine transformer health index. Empirical data obtained from a case study utility suggests that operators and maintainers tend to focus on technical health indices, and this raises concern as to the robustness of decisions to decommission, refurbish, replace, and dispose of transformers in electricity transmission substations. Keywords—electrical transformer technology trends; transformer replacement decisions; substation asset management
Analog Computer Study of Switching Surge Transients for a 500-ky System
Discussion is presented of the results of an analog computer study which was conducted to determine the switching surge transients on the planned 500-kV Southern California Edison Company system and to find a means to limit them to a magnitude which would give economic design parameters for the system.