Introduction. Development of cables for structured cabling systems based on twisted pairs for shipbuilding is carried out in two main directions: increasing the fire safety of cables and increasing the long-term permissible operating temperature by using new, more heat-resistant, electrical insulating materials. Purpose. Substantiation of the possibility of unshielded cables on the basis of unshielded twisted pairs with thermoplastic polyethylene insulation in PVC protective jacket in conditions of high humidity and high operating temperatures on the basis of the results of accelerated aging. Methodology. The cycle of aging under conditions of increased humidity is performed for 336 hours. Then the sample was under natural drying conditions for 1440 hours. Thermal aging in a thermostat at 90 °C was carried out in two stages: first -for 206 hours, the second -for 260 hours. In the initial state and after accelerated aging, measurements of the capacitance and tangent of the dielectric loss angle of all the insulating gaps at frequencies of 100 Hz, 1 and 10 kHz were performed. Results. According to the results of accelerated aging under conditions of high humidity and temperature, it is established that the design of an unshielded cable based on unshielded twisted pairs with thermoplastic polyethylene insulation in a protective coating based on PVC-plastic is resistant to external influencing factors. Practical value. The prolonged holding at temperature of 90 °C is equivalent to operation at temperature of 40 °C for 6.8 years. At higher operating temperatures, the lifetime of the cable is significantly reduced. References 5, tables 1, figures 5. Key words: cables based on twisted pairs for shipbuilding, accelerated aging, hygroscopic moistening, thermal aging, partial capacitance, tangent of the dielectric loss angle, service life.Представлены результаты ускоренного старения в условиях повышенной влажности и температуры образца неэкранированного кабеля на основе витых пар с полиэтиленовой термопластичной изоляцией в защитной оболочке на основе поливинилхлоридного пластиката. Оценка устойчивости кабеля к действию внешних воздействующих факторов выполнена по частичным емкостям и тангенсу угла диэлектрических потерь изоляционных промежутков между жилами. Конструктивная особенность кабеля приводит к группированию частичных емкостей в четыре характерные области. Установлена динамика изменений диэлектрических параметров в процессе гигроскопического увлажнения, естественной сушки и теплового старения при температуре 90 о С образца кабеля. Определены коэффициенты парной корреляции между диэлектрическими параметрами в исходном состоянии и после внешних воздействующих факторов. Показано, что конструкция кабеля устойчива к действию повышенной влажности и температуры. Библ. 5, табл. 1, рис. 5. Ключевые слова: кабели на основе витых пар для судостроения, ускоренное старение, гигроскопическое увлажнение, тепловое старение, частичные емкости, тангенс угла диэлектрических потерь, срок службы.

Introduction. The high saturation of the cable routes of nuclear and thermal stations, wind parks and solar power plants, onboard systems imposes stringent requirements in the field of fire safety of cables, which makes it necessary to use highly flame retardant halogen-free compositions. The introduction of flame retardants causes the mandatory modification (crosslinking) of the polymer matrix. Purpose. Determination of the optimal radiation dose based on the correlation between the mechanical and electrical characteristics of a radiation-modified halogen-free ethylene vinyl acetate copolymer with high-strength flame retardant insulation cables. Methodology. Mechanical and electrical tests of samples of radiation-modified cables with a copper conductor cross section of 1.0 mm 2 and a halogen-free filled insulation based on an EVA copolymer with a thickness of 0.7 mm have been performed. Results. A strong correlation is established between the elongation at break and the tensile strength, between the insulation resistance and the breakdown voltage. It is shown that at the optimum value of the irradiation coefficient in the range from 7 to 5, the insulation resistance increases more than twice, and the breakdown voltage at the direct current is increased by 1.3 times. The elongation at break is within the allowed values. References 12, figures 3.

The cooling mode of polymer insulation after application to the extruder is one of the main factors determining cable performance. Theoretically, it is ideal to cool the insulation when the temperature of the cooling medium is equal to the melting point of the insulation material: in this case, the probability of formation of voids in the insulation is less. The cooling process is usually not subject to stringent requirements, since most insulating materials allow for quite sharp cooling. The exception is polyethylene, which requires gradual cooling. When the insulation is cooled in a cooling bath, the temperature decrease starts from the surface. In this regard, the cooling of the insulation of polyethylene is carried out in steps to a temperature at which the cooled extruded insulation will not be deformed or damaged on the receiving drum. Polyethylene is characterized by a large value of thermal expansion coefficient, the maximum value of which is in the temperature range (90-125) C. As a result, there is an uneven reduction in the volume of the upper and inner insulation layers, especially for cables with a considerable insulation thickness. The rapid cooling of polyethylene leads to the formation of cracks, air inclusions both between the insulation and the conductive core, and in the layers located near the core. Purpose. The substantiation of the technological parameters of the cooling mode of power cables based on the calculation of the thermal equivalent circuit of a conductive core insulated with polyethylene in transient thermal mode. Methodology. The calculation of the temperature distribution in the thickness of extruded polyethylene insulation at different points in time, depending on the temperature of the cooling water, is made by the method of electrothermal analogies. There is a transition from the thermal equivalent circuit of power cables to the equivalent circuit of the discrete resistive equivalent circuit method, which is calculated using the nodal potential method. As a result of solving a three-diagonal system of linear algebraic equations by sweeping and finding at each discretization step (time step) thermal power fluxes in the branches of the thermal equivalent circuit, the temperature in the thermal capacitances determines the temperature in each insulation layer. Practical value. The duration of the transition process, corresponding to the achievement of the same temperature throughout the thickness of the insulation, can be considered as a criterion in determining the length of the cooling bath sections depending on the extrusion (reception) rate. References 12, figures 6. Key words: cooling mode, polyethylene insulation, thermal equivalent circuit, discrete resistive equivalent circuit method, transient mode, nodal potentials method, system of linear algebraic equations, cooling bath length. Обґрунтовано методику розрахунку режиму охолодження силових кабелів в перехідному тепловому режимі. Представлено теплову схему заміщення ізольованої струмопровідної жили. За допомогою методів ...

High-voltage insulation systems always have some background level of the partial discharges, which does not have any significant effect on the life of the electrical insulation design. At the same time, partial discharges destroy high-voltage insulation, leading to a carburization zone around the defect. This is the «hidden» period of development of the defect. The development of a defect zone, sooner or later, leads to an arc breakdown of the entire insulating gap. Purpose. The substantiation of the efficiency of detection of technological defects in high-voltage solid insulation of electrical insulating structures according to the characteristics of partial discharges. Methodology. The conditions for the occurrence of partial discharges in the thickness of the polymer insulation are considered. The possible values of the voltage of the beginning of partial discharges are determined for a model of a cylindrical air gap near the conductor of a power cable. It is shown that with the same applied voltages to highvoltage insulation, in the latter case, air inclusions of smaller thickness are activated in comparison with a flat structure. Practical value. The efficiency of detection of technological defects in solid composite case insulation of the stator winding of turbo-and hydrogenerators is shown. Based on the comparison of the amplitude of the pulses of partial discharges of positive and negative polarity, the estimated location of the technological defects in the insulation has been established. References 19, figures 7, table 1. Key words: technological defects, partial discharges, voltage of the start of partial discharges, glass-mica paper tape, amplitude of pulses of partial discharges, location of the defect. Визначено можливі значення напруги початку часткових розрядів для моделі циліндричного повітряного зазору поблизу струмопровідної жили силового кабелю. Показано, що при однакових прикладених напругах до високовольтної ізоляції в останньому випадку активізуються повітряні включення меншої товщини в порівнянні з пласкою конструкцією. На підставі результатів проведених випробувань силового кабелю на напругу 3 кВ встановлено, що грубі технологічні дефекти в товщі ізоляції відсутні. Амплітуда розрядів в повітряних включеннях не перевищує 10 пКл при прикладеній випробувальній напрузі 5 кВ частоти 50 Гц. Показана ефективність виявлення технологічних дефектів у твердої композитної корпусної ізоляції обмотки статора турбо-і гідрогенераторів. Встановлено, що в макетах, ізоляція яких виконана стрічками меншої товщини, технологічні дефекти розташовані в товщі ізоляції. Для макета, ізоляція якого виконана стрічками більшої товщини, технологічні дефекти у вигляді розшарування розташовані на кордоні розділу провідник-композитна ізоляція. Бібл. 19, табл. 1, рис. 7. Ключові слова: технологічні дефекти, часткові розряди, напруга початку часткових розрядів, склослюдопаперова стрічка, амплітуда імпульсів часткових розрядів, місце розташування дефекту. Определены возможные значения напряжения начала частичных разрядов для...