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Cross-linked polyethylene insulated cable partial discharge test - impact factors Wire and cable

by:AAA     2020-08-22
Crosslinked polyethylene insulated cable partial discharge test factors affecting the hair to the crosslinking polyethylene insulated cable partial discharge test factors affecting xcable cross-linked polyethylene insulating power cable factory test of the partial discharge test is a non-destructive test, the purpose is to determine the sample (s) and measuring in the working voltage without obvious partial discharge. Only under the test voltage is not partial discharge or in accordance with the current national standard does not exceed a certain amount of partial discharge, can guarantee the reliability of insulation. So the partial discharge test is to ensure that product quality and detection of internal defects in insulation. Blew a lot of cable factory equipments put test equipment, and has many years of experience, but as a result of the test equipment system composition is more complicated, high technical content, and affected by many factors, in the process of testing for testers to master the requirements of testing technology. More clearly understand the discharge test of high voltage crosslinked equipment influence factors on the quality of the production and control has important practical significance. Then the influence factors of partial discharge test? ) The source of the problem of interference of partial discharge test interference can be divided into two categories: one is related to the supply voltage disturbance, the second is the interference has nothing to do with the power supply voltage. Has nothing to do with the power supply voltage disturbance is relatively extensive, but generally less affected, mainly refers to the radio, adjacent circuit switch action, rectifying the surge generator motor, high voltage testing ground discharge, etc. ; And interference is usually related to the supply voltage increases with the increase of the test voltage, such as high pressure measurement test of transformer partial discharge, high voltage cables and the corona discharge on the shield, around the metal grounding and sparks, etc. Relevant to a power supply voltage, can generally from test loop to test voltage readings in the measuring instrument when detected, try when testing can be used under the test voltage does not discharge the capacitor ( Or other appliances) Instead, the sample (s) or not connected to the high-voltage lines. ) Defects of wire and cable itself and the problem of raw materials mainly exist in the insulation defects, such as porosity of insulation, impurities, coke, or inner and outer shield bruises will cause partial discharge; Stranded conductor in the process of production of feed water, outside the conductor not clean or insulation, shielding is expected to be affected with damp be affected with damp such as cases, lead to the formation of partial discharge in water filling pores; In addition if insulation semiconduction shielding material resistivity is unqualified, namely when material resistivity than standard value, lost the effect of electromagnetic shielding, will also produce partial discharge in the end of the cable. ) Production process problems of production process is relatively more, such as cable semiconduction shielding on the charred and insulating material. The principal causes of coke burning is the main screen is broken, and or the screen mesh choice mistake. In addition, if the internal and external insulation semiconduction shielding and cross into fangs, the partial discharge of this product is not qualified. So in half a conductive material, when it is squeezed should keep semiconductive materials logistics certain tensile state, the cross section of insulation and semiconduction shielding smooth contact. ) The partial discharge test equipment and deal with the end of the cable at present most of the cable manufacturer adopts hanging type oil cup test terminal for partial discharge test, so for the purity of insulating oil and roughness on the surface of the oil cup should be strictly. Handling of the end of the cable should be no tips, ground of the testing system can lead to good. In addition the insulating oil in the oil cup should be tight during the experiments the cable insulation foam immersion shielding slit, in order to eliminate the generation of surface current and electric field of concentration, or even a very low voltage can also lead to the discharge, resulting in a serious measurement error.
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