Effective Stray Loss Control in Transformers using Various Shielding Measures

Abstract

Transformer is a vital link in the power system network. The transmission and distribution (T & D) loss varies in a range of 10 to 40 % which is considered to be signicant high. Contribution of transformers is in the range of 6 % for T & D losses. In a process of reducing total T & D losses, Loss capitalization for the modern age transformers has increased in a great extent. This indicates necessity of reducing losses (i.e. no load loss and load loss). Stray losses in the transformer contribute around 15 to 40 % in the load losses which is considered to be a significant amount. Hence to match the loss capitalization stray losses shall be reduced. This is achieved by controlling the leakage field. Large rating transformers are with strong electromagnetic field; If the field is not controlled it links with the various structural parts of the transformer e.g. core clamp, tank and will result in to excessive loss concentration, local heating (i.e. hot spots) and further gasification during service conditions. Gasification in the oil can affect reliability of transformer during service conditions. Reliability is at a prime concern for large rating power transformers; all issues related to stray field are addressed to conserve reliability of transformer. Various measures e.g. magnetic and nonmagnetic shields are known to control the stray field in the transformers; each of them their having advantages and disadvantages. Effective solution needs to be selected to make shielding measure more optimum. It is possible to effectively control stray field by use of IEM (integral equation method) and FEM (finite element method) precisely.