Overvoltage propagation from transmission line into transformer winding

The paper deals with very fast transient phenomena in a system consisting of two parts: a cable line and a transformer winding. In this case an adequate model should be considered as a circuit with distributed parameters. Its description is given by a system of partial differential equations of hyperbolic type. Our approach is based on a numerical solution in the time domain and the method FDTD has been used. It allows obtaining results in a form of time-space voltage and current wave distribution along the cable line and the transformer winding. This distribution is depending on many factors some of them were studied in this paper

Mathematical model of MOV surge arrester

The paper deals with a mathematical model of surge arrester which is a very important part of the overvoltage protection of transmission lines and the connected equipment. There is described the basic model and solved numerically. The obtained results from script in MATLAB are verified by model in LTSpice

Static characteristic of components of controllable thermoelastic actuator

The paper deals with one of the basic conditions of practical employment of finely controllable thermoelastic actuators – problems of the static characteristics of its individual structural parts. It contains the formulation of the principle of such thermoelastic actuators, description of its components (a dilatation element heated by induction, auxiliary electromagnetic actuators, and self-locking friction clutches) and their mathematical models. Briefly discussed are also their corresponding computer models making use of the finite element method. The crucial point of the work consists in the presentation of the results – static characteristics of the considered structural parts of the controlled thermoelastic actuators

Propagation of surge waves on non-homogeneous transmission lines induced by lightning stroke

The paper deals with surge phenomena on non-homogeneous transmission lines. The case of surge phenomena caused by the lightning stroke is considered. The lightning is modeled as the current wave injected by the source placed at any internal point of the line. The propagation of the surge wave induced by the lightning affecting the overhead line and transmitting to the cable is evaluated. Problem is solved numerically in the time domain. The efficiency and correctness of the proposed method is shown on some illustrative examples. According to the suggested algorithms is calculated the distribution of induced current and voltage along the whole transmission line namely near to the place of the connection both lines. The manner of the linesconnection is modeled due to various two-ports

Baking of thin electrically non-conductive layers by indirect induction heating

A model of baking electrically non-conductive thin layers (paints, lacquers and other covering material) is presented. The process of baking, whose purpose is to protect the metal substrate from unfavourable influences of environmental medium, is realized by indirect induction heating of the metal substrate that transfers heat to the thin layer by conduction. The electromagnetic and temperature fields in the system are described by two partial differential equations for the magnetic vector potential and temperature. Some important results of the process are verified experimentally with a very good accordance

Inductive coupling effect on induced voltage on three-phase transmission line in consequence of lightning stroke

The paper deals with surge phenomena on hv and vhv three-phase transmission lines with earth wire. The impact of lightning stroke into the earth wire and its influence on parallel phase conductors is investigated. The model of the transmission line is created by network with distributed parameters and concurs on our previous paper. In this paper are derived basic equations respecting not only inductive and capacitive coupling among phase conductors but they involve the coupling phase conductors to the earth wire, as well. Problem is solved numerically in the time domain. Some examples illustrating the propagation of surge wave caused by lightning stroke are solved here

Transients on non-homogeneous line with space varying inductance and capacitance

The paper deals with transient phenomena on non-homogenous transmission line. The problem is solved numerically in time domain, the transmission line with space varying capacitances and inductances is considered. Practical examples are evaluated to prove an efficiency of proposed algorithm

Inductive coupling effect on induced voltage on three-phase transmission line in consequence of lightning stroke

The paper deals with surge phenomena on hv and vhv three-phase transmission lines with earth wire. The impact of lightning stroke into the earth wire and its influence on parallel phase conductors is investigated. The model of the transmission line is created by network with distributed parameters and concurs on our previous paper. In this paper are derived basic equations respecting not only inductive and capacitive coupling among phase conductors but they involve the coupling phase conductors to the earth wire, as well. Problem is solved numerically in the time domain. Some examples illustrating the propagation of surge wave caused by lightning stroke are solved here

The shrink-fit using the rotation heating

Hard-coupled model of rotation heating of a ferromagnetic clamping head is presented. The problem is described by three coupled partial differential equations whose coefficients are temperature-dependent functions. The system is solved numerically in the monolithic formulation and results from different software are compared together. The methodology is illustrated by a concrete example which was built and measured. The results are evaluated and discussed

The influence of arrangement of pernament magnets to rotation heating of ferromagnetic shrink-fit

Several arrangements of pernament magnets forming a magnetic circuit for rotation heating are presented. The problem is solved as hard–coupled model described by three coupled partial differential equations (for the distribution of electromagnetic field, temperature field and field of thermoelastic displacements). The results from the arrangements are compared together and discussed. One of them was built and measured and it verifies the results from the numerical solution