Frequency response analysis (FRA) is a method which is used to detect mechanical faults in transformers. The FRA response of a transformer is determined by its geometry and material properties, and it can be considered as the transformer’s fingerprint. If there are any mechanical changes in the transformer, for example if the windings are moved or distorted, its fingerprint will also be changed...

An overview of the research and developments into new transformer design, undertaken in the Department of Electrical and Computer Engineering, University of Canterbury, is presented. Initially, single phase, 50 Hz, l1/0.23kV pole mount distribution transformers were fitted with either silicon or amorphous steel cores. The transformer tanks were filled with either standard transformer oil or liq...

In this paper, different topologies of dual-frequency modified 3-way Bagley polygon power dividers are designed and analyzed. Equal split power division is achieved at arbitrary design frequencies. In the first structure, two-section transmission line transformer is used to realize the dual-frequency operation. In the second and third structures, dual-frequency T-shaped and π-shaped matching ne...

This paper addresses the optimum transformer design problem to minimize the active part cost of three phase core type distribution transformer. The transformer design process involves substantial heuristic exercise to select the design, best suited to a set of specifications. The design problem considers minimization of total cost of core and conducting material, while constraints are imposed o...

Reliable energy flow is paramount and power transformers are critical, and costly, assets in the grid. As an asset class, power transformers constitute one of the largest investments in a utility’s system. For this reason transformer condition assessment and management is a high priority. In several parts of the world the transformer fleet is operating beyond its design life and with higher ave...

Transformers are normally designed and built for use at rated frequency and sinusoidal load current. A non-linear load on a transformer leads to harmonic power losses which cause increased operational costs and additional heating in transformer parts. It leads to higher losses, early fatigue of insulation, premature failure and reduction of the useful life of the transformer. To prevent these p...

Sweep frequency response analysis is a major advance in transformer condition analysis. Frequency response is performed by applying a low voltage signal of varying frequencies to the transformer windings and measuring both the input and output signals. The ratio of these two signals gives the required response. This ratio is called the transfer function of the transformer from which both the ma...

This paper presents a new approach to identify distributed parameters of a lumped-element model for a power transformer. A simplified circuit of a lumped-element model is developed to calculate frequency responses of transformer windings in a wide range of frequency domain. In order to seek optimal parameters of the simplified circuit of the transformer, an intelligent learning technique, based...

This paper describes a procedure for frequency dependent modeling of power transformers from measured terminal characteristics. The admittance matrix is measured in the frequency domain using a network analyzer and a dedicated measurement setup. Subsequent approximation of the admittance matrix with rational functions using Vector Fitting gives an EMTP-type compatible model suitable for transie...

Spiral inductors fabricated using a 90nm CMOS process have been characterized and analyzed. The extracted series resistance increases with frequency and temperature. The extracted resistance temperature coefficient exhibits a strong dependence on operating frequency. It gradually decreases with frequency and is different from the results using DC temperature coefficients. A single π-model is us...