Analysis of Power Transformer Insulation Design Using FEM
Tathagat Chakraborty1, Akik Biswas2, Sudha R3

1Tathagat Chakraborty, School of Electrical Sciences and Technology, VIT University, Vellore – 632014, Tamil Nadu, India
2Akik Biswas, School of Electrical Sciences and Technology, VIT University, Vellore – 632014, Tamil Nadu, India
Sudha R., School of Electrical Sciences and Technology, VIT University, Vellore – 632014, Tamil Nadu, India
Manuscript received on July 01, 2012. | Revised Manuscript received on July 04, 2012. | Manuscript published on July 05, 2012. | PP: 366-369 | Volume-2, Issue-3, July 2012. | Retrieval Number: C0745062312 /2012©BEIESP
Open Access | Ethics and Policies | Cite 
© The Authors. Published By: Blue Eyes Intelligence Engineering and Sciences Publication (BEIESP). This is an open access article under the CC BY-NC-ND license (

Abstract: A transformer is a device that transfers electrical energy from one circuit to another through inductively coupled conductors—the transformer’s coils. A varying current in the first or primary winding creates a varying magnetic flux in the transformer’s core and thus a varying magnetic field through the secondary winding. This varying magnetic field induces a varying electromotive force (EMF), or “voltage”, in the secondary winding. This effect is called inductive coupling. If a load is connected to the secondary, current will flow in the secondary winding, and electrical energy will be transferred from the primary circuit through the transformer to the load. In an ideal transformer, the induced voltage in the secondary winding (Vs) is in proportion to the primary voltage (Vp) and is given by the ratio of the number of turns in the secondary (Ns) to the number of turns in the primary (Np) as follows: By appropriate selection of the ratio of turns, a transformer thus enables an alternating current (AC) voltage to be “stepped up” by making Ns greater than Np, or “stepped down” by making Ns less than Np. In the vast majority of transformers, the windings are coils wound around a ferromagnetic core, air-core transformers being a notable exception. Transformers range in size from a thumbnail-sized coupling transformer hidden inside a stage microphone to huge units weighing hundreds of tons used to interconnect portions of power grids. All operate on the same basic principles, although the range of designs is wide. While new technologies have eliminated the need for transformers in some electronic circuits, transformers are still found in nearly all electronic devices designed for household (“mains”) voltage. Transformers are essential for high-voltage electric power transmission, which makes long-distance transmission economically practical. Finite element modeling (FEM) is a useful and commonly used tool in the solution of electromagnetic problems that arise in the design of power transformers. With approximately 30% of all transformer failures being due to insulation breakdown (due to excessive electrostatic stress), electrostatic FEM techniques are providing engineers with a valuable means of more accurately quantifying the electric stress in their designs. The validity of FEM, in general, always depends on having sound modeling assumptions and techniques. In addition, this problem introduced further complications that required carefully considered assumptions and treatments.

Keywords: EMF, FEM