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The issue of designing devices with optimal characteristics of converting an electrical signal and its shape without distortion is relevant when developing a device with small dimensions for electric rolling stock. In this article, the influence of transformer parameters on the form of voltage transmission is considered and recommendations are given on the choice of values of these parameters. This applies to pulse, differential, and low-power transformers. The study of this issue is moving from theory to constructive calculation. In the era of digital twin design, the computational mathematical model of the transformer will allow for a quick decision on compliance with the inherent requirements for the product. Being universal, the proposed model allows performing calculations for any pulse transformer, provided that the appropriate initial data is specified and will allow obtaining an estimated characteristic of the transformer already at the design stage. The study showed the relationship between the transformer design, the materials used for the magnetic circuit and the shape of the output signal. Obviously, the dissipation inductance and the capacitance of the windings are the main parameters that introduce distortion into the signal. Modeling of the winding design and the selection of magnetic alloys or ferrites help to reduce eddy currents in the magnetic circuit, which improves the characteristics of the output signal and reduces the effect of the constant component of the current at the end of the pulse. A transformer model with reduced core dimensions made of steel with a smaller rolled thickness and a homogeneous domain structure, as well as the use of a distributed winding along the core, which has a minimum intrinsic capacitance, had the least effect on the output signal with an acceptable signal distortion of 3 %. The resulting transformer model can be used to create a finished product.

The authors consider the question of the limits of applicability of the capacitor method for measuring the real part of the dielectric constant of printed circuit boards and telecommunications cabled rail transport using the example of FR-4 fiberglass laminate and the cable PK-75-4-12 in the frequency range from 10 Hz to 100 MHz. The measurements were carried out at a constant temperature and humidity of a known material. Comparison of the obtained values with the passport data on the material is carried out; a measurement procedure is developed with overlapping frequency ranges by changing the values of the measuring resistors from larger to smaller with increasing frequency of the input signal. It is shown that in the high-frequency region, the measurement accuracy is directly affected by the parasitic inductance of the capacitor sample under study, as well as the active resistance of the leads and plates and its increase due to the skin effect. The article also discusses the ways of accounting and calculating the parasitic elements of a capacitor. One of these ways is to study the characteristics of the elements of the sample at the first proper serial resonance of the capacitor under study.