The physical process features at the point of contact of the electric rolling stock current collector and the contact wire in the system of traction power supply of DC Railways are considered. The choice of parameters of the combating icy frost formations on the wires of the contact network by melting ice method is justified

Keywords: physical process, an electric arc, melting of ice, the estimated coefficients, the choice

The short analysis the direct-current motor running with the help of regulating resistors and thermostatic resistors is made. A fixed range of thermistor resistors can be obtained by optimizing the current. There are some graphical dependence of the load moment influences on the engine acceleration through the semiconductor rheostat. The authors give some warning to combine starting rheostats.

Keywords: thermistor, starting rheostat, direct-current motor, motor starting current line graph, combined starting resistance

The authors examine the peculiarities of fiber-optic cable electric parameters changes under the influence of a strong homogeneous alternating electromagnetic field. Variants of the process which can be used to describe the influence of the electromagnetic field on the fiber-optic cable are proposed.

Keywords: Fiber optic cable, electrothermal degradation, kevlar, electrical conduction

Thermoresistors nowadays are used not only as parts of temperature sensors and flowmeters but they are used as components of starting and control devices. Use of low-powered thermoresistors as starting and control devices parts needs a lot of devices that reduces equipment reliability. Current step-up running through motor-starting devices simplifies control circuit. For using thermoresistors in electric circuits with high-discharge rate it is necessary to use special constructions in order not to let termoresistor body be overheated. Thermoresistor expansion results in changing of thermal fields distribution pattern inside this semiconductor. The authors show calculated characteristics which let determine proportions and shapes of semiconductor subject to thermoresistor temperature.

Keywords: high power thermoresistors, thermoresistors of coaxial type, current density, temperature, analogy criterion, thermal conductance, temperature gradient, thermal field, stability criterion