CC BY
15TECHNICAL SCIENCES
QUALITY CONTROL AND EVALUATION OF THE LIFE CYCLE INSULATED POWER CABLES
XLPE
Gontar Yu.
Master of Production, Department of Electrical Insulation and Cable Engineering, National Technical University "Kharkiv Polytechnic Institute "
Kharkiv, Ukraine Kiessaiev O.
Ph. D. (Tech.), Head of the Department of Electrical Insulation and Cable Engineering, National Technical University "Kharkiv Polytechnic Institute "
Kharkiv, Ukraine Antonets T.
Ph. D. (Tech.), deputy chief technologist, «YUZHCABLE Works» PJSC
Kharkiv, Ukraine
Abstract
The undoubted advantages of cables with XLPE insulation in comparison with cables with impregnated paper insulation are considered. Such cables are more reliable in operation. The need for design is based on technological and design features, on the number of defects, on the technology to be prepared and by the minds of the operation. Reliability is determined by technological and design features, the absence of defects, manufacturing technology and operating conditions. Tests are an integral part of cable life cycle. Life cycle assessment is an important tool for determining the actual service life. Analysis of the data obtained during the tests allows you to assess the life cycle of the cable.
Keywords: Medium voltage power cables, XLPE insulated cables, cable life cycle, cable system test methods, reliability.
In recent decades, the vector of development of medium voltage cable distribution networks is aimed at the introduction of cables with cross-linked polyethylene (XLPE) insulation. Lines that use cables with impregnated paper insulation have already developed their resource and the intensity of their failures is quite high. Cables with cross-linked polyethylene insulation have significant advantages over cables with paper impregnated insulation; they are more reliable in operation, require lower costs for installation and reconstruction [5,6]. A comparison of the main performance of cables with cross-linked polyethylene insulation and cables with paper impregnated insulation is shown in Table 1.
Table 1
Comparison of the main performance of medium voltage cables with XLPE insulation and cables with paper im-
These data are confirmed by almost forty years of experience in the operation of such cables in most industrialized countries. For example, the proportion of cables with XLPE insulation with the United States and Canada share is 85% in Germany and of Denmark -95% in Japan, France, Finland and Sweden in medium voltage distribution networks used only cable with XLPE insulation. In the CIS countries, for the first time, the industrial production of cables with cross-linked polyethylene insulation for voltages from 6 to 330 kV was mastered in Ukraine at the «YUZHCABLE Works» PJSC.
The main indicators Cables with paper impregnated insulation Cables with XLPE insulation
Long-term permissible operating temperature, C 70 90
Resistance to short-circuit currents, °C 200 250
Load capacity, % - when laying in the ground - when laying in the air 108 116 125 137
The difference of levels on the track when laying, m 15 without limits
The complexity in installation and repairs high low
Durability and safety of operation of electric cables depends on their reliability. Reliability is determined by such factors as technological and design features, the absence of defects, manufacturing technology and operating conditions.
First of all, high demands are placed on cable production technology.
In fig. 1 shows the main and additional measures to be taken by manufacturers to maintain high quality
cable products. All manufactured products must comply with regulatory documentation for each type of product and the requirements of current legislation of Ukraine. In addition, it is necessary to assess the products for compliance with the Technical Regulations and Directives of the European Union, as well as product certification.
NO DEFECTS ON THE SURFACE OF A CURRENT CORD
measures: CLEANING FROM METAL DUST; PROVIDING A SMOOTH SURFACE
NO INCLUSIONS AND VACUUM IN THE INSULATION /
measures: THREE-LAYER EXTRUSION. SELECTION OF THERMAL MODE.
SMOOTH SURFACE OF EXTRUDED SCREENS
measures:
PURE COMPOSITION OF PE. CLEANING OF EXTRUSION EQUIPMENT
measures:
LONG CABLE TEST IN A HUMID ENVIRONMENT
AT A HIGHER VOLTAGE TO CONFIRM RELIABILITY IN OPERATION
measures:
PERIODIC QUALITY CONTROL OF THE INSULATION SYSTEM BY ANALYSIS OF ELECTRIC
STRENGTH OF CABLES AT PULSE OR AC VOLTAGE. 1 every 6-12 months
Fig. 1. Quality control diagram for the manufacture of XLPE insulated medium voltage cables
Immediately after construction, as well as during operation, cable lines are subjected to various tests, which detect weaknesses or defects in the insulation and protective sheaths of cables and fittings.
The main technical characteristic of the transmission capacity of the power cable is the long-term permissible current under normalized operating conditions (100% load factor) [1]. These normalized conditions are:
1) stationary load mode;
2) normalized maximum permissible core temperature;
3) normalized ambient temperature;
4) typical type of environment for laying (ground, air, special structures);
5) normalized thermal parameters of the environment (specific thermal resistance of soil, coefficient of heat transfer from the surface of the cable in air, etc.).
To ensure the reliability of cable lines, a system of planned and preventive tests is used. According to such tests, the cables are periodically exposed to a fairly high level of direct current with the measurement of leakage currents. However, such test methods not only do not guarantee trouble-free further operation of the cable, but can also lead to a reduction in cable life.
Non-destructive methods of testing medium voltage cable lines are widely used in the world:
• method of measuring and determining the location of partial discharges in power lines;
• method of measuring and analyzing the reverse voltage in the insulation;
• method of measuring the relaxation current in isolation;
• method of measuring the dielectric characteristics of cable insulation;
• method of pulse reflectometry for preliminary localization of low-impedance damage in power lines;
• method of preliminary localization of high-impedance damage in CL;
• method of control of integrity of a cover of power cables and definition of places of malfunction in covers.
In medium voltage cable lines of the main causes of aging of insulation during operation (reduced electric strength) is the effect of partial discharges and elevated temperatures. In world practice, a direct assessment of the operational capacity of the cable is used in the form of long tests [1], the so-called long term test, which is also called resource tests. Long duration (annual or biennial) and significant cost make these tests inaccessible for use in real production conditions [2].
Testing is an integral part of the cable life cycle. Life cycle assessment is an important tool for determining the actual service life. In the overall life cycle of XLPE cables, tests to verify the quality of the cable itself include 2U0 hot cycle tests with 50/60 Hz alternating current (AC) or 20-300 Hz alternating current (ACRF) or alternating current ultra-low frequency 0.01-1 Hz (VLF), measurement of the tangent of dielectric loss angle tg 6 and partial discharges of PD at (1.75-1.5)U0 [3].
In recent years, there has been a tendency to decrease the level of the test voltage and decrease the frequency with a simultaneous increase in the duration of tests and their saturation with diagnostic procedures to reduce the destructive effect of test voltages on insulation [1-3].
Analysis of the data obtained during the tests allows you to assess the life cycle of the cable. These are laboratory tests for accelerated aging, and tests of cables obsolete during operation. Dow Electrical & Telecommunication (DowE&T) has conducted comparative tests to maintain the electrical strength of XLPE insulated medium voltage cables and ethylene-propylene rubber-insulated cables, laid underground and operated for 17 years. The results of these field and laboratory tests for accelerated aging in a humid environment have shown that cables with XLPE insulated insulation can last at least 40 years.
Comparing the test results of cable materials for aging can be one of the reliable factors in assessing the life cycle of a cable product. Such tests prove that high-quality materials manufactured in accordance with the standards ensure long-term preservation of the performance of cables and, as a result, the entire power system.
Conclusions: The undoubted advantages of cables with XLPE insulation in comparison with cables with impregnated paper insulation are considered. Such cables are more reliable in operation. Reliability is determined by technological and design features, the absence of defects, manufacturing technology and operating conditions. Tests are an integral part of cable life cycle. Life cycle assessment is an important tool for determining the actual service life. Analysis of the data obtained during the tests allows you to assess the life cycle of the cable.
References
1. IEC 60840 - Ed.3.0. Power cables with extruded insulation and their accessories for rated Voltages above 30 kV (Um = 36 kV) up to150 kV (Um = 170 kV) - Test methods and requirements. - 2004.
2. СHГРЭ № 303 «Revision of qualification procedures for high voltage and extra high voltage AC extruded underground cable systems». - 2006.
3. S.C. Moh, "Very low frequency testing-its effectiveness in detecting hidden defects in cables, 17th international conference on electricity distribution, Cired, Barcelona, 2003.
4. Distribution of the temperature in the power undersea cables. Electrical Insulation and Dielectric Phenomena, 2010. CEIDP '4. IEEE Conference. 01-03 Mar. 2010. p. 119 - 121.
5. Larina Je.T. Silovye kabeli i vysokovol'tnye kabel'nye linii. [Power cables and high voltage cable lines] Moscow, Energoatomizdat Publ., 1996. 464 p.
6. Karpushenko V.P., Shhebenjuk L.A., An-tonec' Ju.A., Naumenko O.A. Silovi kabeli niz'koi' ta seredn'oi' naprugi. [Low and medium voltage power cables] Kharkiv, Region-inform Publ.,2000. 376 p.
МАТЕМАТИЧНЕ МОДЕЛЮВАННЯ ТОПОЛОГ1Й МЕРЕЖ VANET
Виштвський В.В.
Державний унгверситет телекомунгкацш, завгдувач кафедри комп'ютерних наук, д.т.н., професор,
м. Кшв, Украша Зшченко О.В.
Державний унгверситет телекомунгкацт, завгдувач кафедри штучного ттелекту, к.т.н., доцент,
м. Кшв, Украша Березовська Ю.В.
Державний унгверситет телекомунгкацш, аспгрант, м. Кшв, Украша
Березiвський М.Ю.
Державний унгверситет телекомунгкацш, аспгрант, м. Кшв, Украша
MATHEMATICAL MODELING OF VANET NETWORK TOPOLOGIES
Vyshnivskyi V.
State University of Telecommunications, Head of Department of Computer Science, Doctor of Technical
Sciences, Professor, Kyiv, Ukraine Zinchenko O.
State University of Telecommunications, Head of Department of Artificial Intelligence, candidate of science
(technic), associate professor, Kyiv, Ukraine
Berezovska Yu.
State University of Telecommunications, postgraduate student, Kyiv, Ukraine
Berezivskyi M. Y.
State University of Telecommunications, postgraduate student, Kyiv, Ukraine
