FOT

Wire and cable on-line monitoring condition and method

by:FOT     2020-07-15
In recent years, with the wide use of described. properties power cable, described. properties for safe operation and management, power cable power cable insulation online monitoring technology obtained the rapid development. Abroad began in the early 20 century 60 s described. properties of cable insulation aging vulnerability detection and monitoring technology research, is still in the further development, especially in Europe and the United States and Et in this and other developed countries have accumulated some experience. Described. properties abroad in online monitoring system for the cable aging development process provides a large number of monitoring results, the rich and the criterion of aging of cable defects; Degradation and crosslinking cable system development trend, combined with the monitoring results of comprehensive analysis, try to carry out the described. properties of power cable aging residual life assessment of the insulation of ontology and its accessories. Is Japan described. properties cable insulation aging defect detection technology in terms of practice, cable detection technology for 10 kv and below are not on-line and on-line. Not include on-line, the absorption current, residual voltage dc leakage current, potential attenuation method ( Dc) ; Residual charge, dc voltage superposition method ( Dc and power frequency) ; Ac loss current method ( Power frequency) ; Dielectric loss method ( Ultra-low frequency) 。 Online, including: the dc component, pulse method ( Power frequency) ; Dc voltage superposition method ( Dc and power frequency) And so on. For higher voltage class, there is no on-line, with not only on-line, and no longer use the absorption current, dc component, pulse method, such as increased such as dc bias, partial discharge, compression method. Other countries have to partial discharge test described. properties used in high voltage cable and its accessories, such as the Netherlands, Switzerland, the UK, etc. On the basis of GB9330 - at present domestic to low voltage cable - - - - - - 1988, using the method of pressure rise step by step, control cable thermal aging experiments and as a test basis and calculation method. At the same time there are many scholars and research units to track monitoring techniques and methods of the foreign research, accumulated some criterion about cable defect detection and aging, but in the 110 kv and above described. properties cable has no systematic research and engineering application. Although the low and medium voltage grade cable insulation aging defects detection method diversification development, accumulated quite a test data, to achieve effective judgment detection; And high voltage cable aging test method is different, part of the method is confirmed by the electric power department. So far are described. properties cable insulation aging diagnosis technology development, 110 kv and above level of practice in a high pressure level is far less rich, need further study, but tend to implement on-line partial discharge detection and cable temperature monitoring has become a consensus. Described. properties cable implementation of partial discharge detection means the main problem is: on the road at the scene of the determination of the environment is more under the condition of interference sources, how to improve the partial discharge detection sensitivity. Therefore, the foreign developed high frequency discharge ( HFPD) Or discharge (very high frequency VHFPD) New type of detector. Shanghai jiaotong university laboratory has developed a high voltage discharge measurement system, high frequency on the cable, ontology, joint, and the end of the on-site partial discharge detection and meet the real-time sampling analysis of partial discharge signal, the discharge signal recognition and discharge size determination. Now another described. properties of power cable protection monitoring measures the whole cable real-time temperature monitoring and tapping temperature monitoring assessment technology. When the cable is local overheating due to unknown reason, or in the electricity peak period, full load running described. properties of power cable conductor temperature rise has reached the highest working temperature, the cable insulation will tolerate more than the normal working conditions. So in order to ensure the safe operation of the cable, need to monitor multiple cable joint temperature change at the same time, and USES the mathematical physics model of cable joint calculation and analysis of conductor temperature, to ensure the safe operation of the cable.
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