s – Detection of minor faults in power transformer active part is essential because minor faults may develop and lead to major faults and finally irretrievable damages occur. Sweep Frequency Response Analysis (SFRA) is an effective low-voltage, off-line diagnostic tool used for finding out any possible winding displacement or mechanical deterioration inside the Transformer, due to large electro...

To study the voltage distribution in transformer windings under VFTO, a model for transformer windings has been developed based on Multi-conductor Transmission-Lines (MTLs) theory and the computing equations of the model based on FiniteDifference Time-Domain method (FDTD) is deduced. The Vector Fitting method is adopted to treat the frequency-dependent parameter by expanding the time-domain for...

The impact of initial conditions on the initiation of fundamental frequency ferroresonance is investigated. The investigation is carried out by simulating the behaviour of the mathematical model of ferroresonant circuit realized in the laboratory. The initiation of fundamental frequency ferroresonance is investigated by varying the values of phase angle and amplitude of voltage source in order ...

A procedure for optimum design of a high-power, high-frequency transformer is PresentedThe Procedure is based on both electrical and thermal processes in the transformer and identifies a) the VA-rating of ferrite cores in relation to the operating frequency, , , ) the optimum flux density in the core, and c) the optimum current densities of the windings providing maximum transformer efficiency....

Reliability of a power system is considerably influenced by its equipments. Power transformers are one of the most critical and expensive equipments of a power system and their proper functions are vital for the substations and utilities. Therefore, reliability model of power transformer is very important in the risk assessment of the engineering systems. This model shows the characteristic...

A frequency domain filtered-x type least mean active sound intensity adaptive control algorithm based on waveform synthesis is developed for active control of transformer noise. The algorithm is useful for providing global control of transformer noise by minirnising the mean active sound intensities for the fundamental frequency and its harmonics in the near acoustic field of the transformer. M...

In this paper, a 24 GHz transformer-coupled VCO is presented for a wide linear tuning range in the 0.13-μm CMOS process. The measured results of the proposed VCO show that the center frequency is 23.5 GHz with 7.4% frequency tuning range. The output frequency curve has wide linear tuning region (5.5%) at the middle of the curve. Also, the VCO exhibits good phase noise of −110.23 dBc/Hz at an of...

Inrush current is a very important phenomenon which occurs in transformer during energization at no load. It depends on several factors like magnetizing properties of magnetic material, resistant and inductance of primary winding, supply frequency, switching angle of circuit breaker, applied voltage etc. Objective of this study is to estimate the maximum value of transformer inrush current. Mea...

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...