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...

This paper presents an alternative approach using the differential logic associated to Artificial Neural Networks (ANNs) in order to distinguish between inrush currents and internal faults in the protection of power transformers. The Alternative Transients Program (ATP) has been chosen as the computational tool to simulate a power transformer under fault and energization situations. The Radius ...

Inrush currents in transformers are non-sinusoidal, high magnitude currents generated due to flux saturation in the core during energization. For protection purpose, in this paper an efficient method for detection of inrush current in distribution transformer based on wavelet transform is presented. Using this method inrush current can be discriminated from the other switching transients such a...

Intriguing mal-operations and fail-to-trip of the differential protection of the converter transformer in the HVDC system are reported. In this paper, the mechanism of these abnormal operation behaviors is analyzed. By virtue of deliberately designed models of the converter transformer and the HVDC transmission system, a variety of simulation tests are carried out and above mentioned strange op...

Resonant temporary overvoltages during transformer energization may result in damage to the itself or surrounding equipment. These are caused by interplay between currents and grid impedance. Current practice assess risk of is classifying scenarios into potentially problematic non-problematic based on magnitude impedance at frequencies coinciding with harmonic frequencies. At moment, this appro...

Energization of a transformer results in sudden flow of current which is an effect of core magnetization. This current will be dominated by the presence of second harmonic, which in turn is used to segregate fault and inrush current, thus guaranteeing proper operation of the relay. This additional security in the relay sometimes obstructs or delays differential protection in a specific scenario...

The main goal of this paper is the determination of the effect of the metal oxide varistor (MOV) on various ferroresonance modes including fundamental resonance, subharmonic and chaos mode which are generated in electrical power systems. Chaos theory is used for analyzing this effect. Also, the bifurcation, phase plan diagram and time domain simulation are used for this purpose. The proposed po...

In this paper an analysis of different designs of traction transformers is given. The paper describes three-limb transformer design for 7.5 MVA and 10 MVA units and two-limb transformer design for 15 MVA and 16 MVA units. Paper also represents noise level measurement results and sound intensity frequency spectrum for 16 MVA unit. Based on results of measurements taken during heat run test on tr...

In this article, a transformer model is presented that applicable to low frequency electromagnetic transient phenomena of up 1 kHz. An example the energization no-load analyzed. A simplifed analytical approach first. Due limitations approach, numerical introduced for solution stiff differential equations describe phenomena. both cases, algorithms have been developed generating waveforms state v...