The manual corresponds to the state educational standard of the discipline "Mathematical modeling of PLU" of the bachelor's training direction "Electrical engineering, electromechanics, electrotechnology" . The manual is devoted to solving the energy balance equation for high-frequency induction and arc plasmotrons, which are the source of high-energy plasma and are used in various technologies. The energy balance equation, which expresses the law of energy conservation and describes the energy processes occurring in plasmotrons, is solved using a physically clear and widespread method - the control volume method. As a result, there is a distribution of plasma temperature in the plasmotron .. The manual provides examples of energy balance solution programs written in the MathCAD environment, the distinctive feature of which is the representation of all mathematical operations (multiplication, division, grading, etc.) ) in the traditional form, and the possibilities are approaching the capabilities of programming languages (such as C, Pascal, Fortran, etc.) ). The manual is intended for students of the third - fifth courses .