24-09-2014, 03:37 PM
RECENT TRENDS IN TRANSFORMER DESIGN
RECENT TRENDS.docx (Size: 236.92 KB / Downloads: 49)
Abstract:
Practical transformer design requires knowledge of electrical principles, materials, and economics. Small transformers, under 10 kVA, may be designed using handbook data and pencil-and-paper calculations, but larger or mass-produced units are often designed with extensive computer aided modeling (CAM) and finite element analysis (FEA).the impressive progress of transformer technology in recent decades is based on two factors: improved character tics of material, especially core material and development of advanced design tools. In this paper, we are discussing different types of transformers namely: Energy efficient distribution transformers- amorphous core transformer, gas insulated transformers, Rectifier transformers.
Introduction
Amorphous materials were developed in the seventies of the last century. These materials are produced by rapid solidification of a liquid alloy, what gives specific magnetic properties, especially very low energy loss. However, these materials have quite low saturation induction and they are thermal unstableProduction technology and properties of amorphous materials were described. Distribution transformers are units of electric power systems, in which electricity is transformed form the voltage level 1 - 50 kV to the voltage level 120 V + 1 kV, in dependence on consumers’ needs. Energy efficiency of distribution transformers is very high, typically ranging between 96% and 99%. However, due to a large number of distribution transformers in electric power system and their long lifetime (30 - 40 years), even small improvement in the efficiency of these units could result in significant energy savings.
Amorphous Core Transformers
Construction:
Amorphous cores are usually produced as wounded, one-side cutting ones, due to mechanical properties of amorphous ribbons. This solution ensures the correct location of air gaps inside a core and simplifies electric windings assembling as well. Amorphous transformers are produced as 1-phase or 3-phase units, with 3-limbs or 5-limbs core construction. The capacity of currently produced amorphous transformers is limited up to 10 MVA. The construction of an oil immersed type amorphous transformer produced by Hitachi Corporation, which is representative for this kind of transformers
Energy Savings and Economic Profits of Amorphous Transformers
No-load loss of amorphous core transformers is very low comparing to conventional transformers with silicon steel core. It results from very low energy loss of amorphous ribbons and also its small thickness, what significant reduces eddy currents flow. The reduction of no-load. Significant energy savings result in decrease of fuel consumption in power plants, what reduces the emission of greenhouse gases. This issue is important form social considerations and for economic policy, because it simplifies the fulfillment of the international agreements of environment protection.
Rectifier Transformers:
Rectifier transformers are transformers used to feed a rectifier circuit which converts an AC current into a DC current. Due to the small conduction angle when feeding a rectifier & reservoir (capacitor), the rms AC current in the transformers secondary is somewhat higher than the DC load current. Each rectifier circuit has different conduction angles, and thus different rms current needs. The proper rms current the transformer needs to supply, and the volt amperes of each secondary, is calculated using the following formulae. (Note: Some may use "S" in place of "VA" in the following formulae). The formulae below do not take into consideration any extra current needed by voltage regulation circuits fed by the rectifier/filter assembly. They need to be added to the total power that the rectifier circuit will feed. Each rectifier and voltage regulation system uses different amounts of current, and each case has to be calculated differently.
Conclusion
In this paper introduce new materials, to develop components and processing methods to promote resource conservation and recycling, to further develop advanced technology in response to the requirements of society, and to implement useful proposal for reducing the total life cycle cost, that is to help optimize the investment of the customer side. In addition it also continues the development of transformer peripherals, for example Active noise control