A distributed system of protection and diagnostics of support structural elements of high-voltage power lines (HVPL) on 500 kV voltage was developed at Karaganda State technical university: -current monitoring of leakage currents of bunches of suspension insulators; -detection ice-rime depositions; -cathode protection of underground elements of support constructions; -information transfer from the sensors placed on supports on the control office on telemetric channels; -creation of the passport of each support on SCADA -system basis.The system contains set of local subsystems of protection, measurement, processing and information transfer on support, communication links and a subsystem processing and information storage on the control offices. Power supply of local subsystems is provided by the directed energy of electromagnetic fields. Detection of ice-rime deposits is carried out by the indirect methods based on the current monitoring of the support response of wind and ice loads and also temperatures and air humidity. Sensors information allows to control integral values of a leakage current of industrial frequency and surface currents of the partial discharges proceeding through strings of insulators and also to define the time-point optimum for drop-out ice-rime deposits. Radio modem and cellular communication with an automatic choice of the communication channels in the conditions of the powerful electromagnetic fields have a significant effect on an opportunity and transmission quality of information are used for transmission the telemetric information to the control office. Tests with the positive results of the experimental samples of all components of system are carried out on the operating line and in laboratories. The developed system is a basis for methods creation and technical solutions on lowering the losses of the electric power in case of its transportation on 110 and 220 kV HVPL.

As a result of the executed researches of the generating modes of the thyristor electric drive for the ground ropeways, winches of drilling rigs and other equipment with the sign-variable moment of loading was determined that the mode of recuperative braking could be realized only in case of great and average values of the electromotor speed in difference from the electric drive of a direct current in case of power supply from an ideal source of a direct current. The technical solution which excludes unstable operation modes in the countercurrent mode at small speeds was offered and it automatically provides a choice of the necessary generating mode of a recuperation or a countercurrent. Theoretical researches of the emergency braking modes connected to blackout, the need of implementation of which is caused by safety regulations which impose strict requirements to the brake way length of the main mining equipment were executed. The technical solution on the basis of the dynamic braking system with the shunting diode connected parallel to the engine drive winding is developed that allows to use the energy accumulated in the drive winding for implementation of the mode of emergency braking.

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One of the most common types of AC electric machines are asynchronous electric motors. Because of their simple and reliable design, they are used in many industries. In this paper, the object of research is an asynchronous electric motor with a short-circuited rotor. To ensure the normal operation of an asynchronous electric motor, the heating temperature of its active parts should not exceed the maximum permissible values, which are determined by the corresponding class of heat resistance of the insulation system used in the electric motor. In asynchronous electric motors, the stator winding is the most thermally vulnerable node, which is the first to fail when the temperature of the electric motor increases. Thermal protection devices protect an asynchronous electric motor from emergency operating modes accompanied by an unacceptable excess of the temperature of their windings. In order to build an indirect system of protection against overheating of the stator windings, a temperature observer has been developed using already available signals in a frequency-controlled electric drive. Simulation studies were performed in Matlab/Simulink application software packages. Simulation studies were carried out on the basis of asynchronous electric motors of the 4A series with a capacity of 30, 75 and 110 kW in the temperature range from 20 °C to 250 °C. As a result of the research, it was found that the error of indirect calculation of the temperature of electric motors, taking into account the correction factor, does not exceed 1 %. The proposed temperature observer can be used to build protections for asynchronous electric drives

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