this paper presents a new arc starter circuit that is usable in manual metal arc welding (mma) power supplies. the proposed circuit uses an auxiliary circuit and a series coupling transformer for adding high frequency spikes to output dc voltage during arc striking. the proposed circuit is usable in inverter based arc welding supplies and it could result in a decrease of weigh, volume and expen...

Multilevel inverters are a source of high power, often used in medium-voltage application. Multilevel converters have received increased interest recently due to high quality output waveform and decrease the harmonic distortion in the output waveform without decreasing the inverter power output. A multilevel inverter uses a series of semiconductor power converters, thus generating higher voltag...

This research studies the forces on the windings of transformer due to inrush current. These forces are compared with the corresponding forces due to short-circuit of the windings. Twodimensional finite element computation of a single-phase shell-type transformer is carried out based on the maximum permissible inrush current value where its amplitude is the same as the rated shortcircuit curren...

ac railway traction loads are usually huge single phase loads. as a result, a significant amount of negative sequence current (nsc) is injected into utility grid. moreover, harmonics and consumption ofreactive power are further power quality problems that the supply network is encountering. in this paper, acompensation strategy with the aid of railway power conditioner (rpc) is proposed to over...

The objective of this research is to compute the mechanical stresses in power transformer resulting from the currents more than rated value during its operation. Due to this high fault current, mechanical stresses are produced indifferent directions which may cause the damage of winding insulation. Various techniques have been adopted to analyze the stresses on transformer windings. For the acc...

In transformers the main consequence of harmonic currents is an increase in losses, mainly in windings, because of the deformation of the leakage fields. Higher losses means that more heat is generated in the transformer so that the operating temperature increases, leading to deterioration of the insulation and a potential reduction in lifetime. This paper includes the effects of non-sinusoidal...

In the power system voltage sag become the important issue for industries. According to the survey 92% of the interruptions at industrial installations are voltage sag related. In various companies voltage sag may affect many manufactures and introduce sufficient losses in the power system. The voltage sag compensator, based on a transformer coupled series connected voltage source inverter, is ...

At high frequency, the winding losses of power transformer due to skin and proximity effects becomes a significant component in the loss calculation of the transformer efficiency. This paper examines the winding losses associated with these effects for planar-type low-profile transformers that are suitable for high frequency high density soft switching power supply application. The transformer ...

Transformer inrush currents are high-magnitude, harmonic-rich currents generated when transformer cores are driven into saturation during energization. These currents have undesirable effects, including potential damage or loss-of-life to the transformer, protective relay misoperation, and reduced power quality on the system. Controlled transformer switching can potentially eliminate these tran...