scholarly journals Effect of sPP Content on Electrical Tree Growth Characteristics in PP-Blended Cable Insulation

Materials ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 5360
Author(s):  
Shuofan Zhou ◽  
Fan Yu ◽  
Wei Yang ◽  
Zhonglei Li ◽  
Zhaoliang Xing ◽  
...  
Keyword(s):  
Crystalline Morphology ◽  
Excellent Performance ◽  
Syndiotactic Polypropylene ◽  
Cable Insulation ◽  
Deep Traps ◽  
Electrical Tree ◽  
Negative Effect ◽  
Carrier Traps ◽  
Electrical Treeing ◽  
Heterogeneous Crystallization

This paper aims at investigating the electrical tree characteristics of isotactic polypropylene (iPP)/syndiotactic polypropylene (sPP) blends for thermoplastic cable insulation. PP blended samples with sPP contents of 0, 5, 15, 30, and 45 wt% are prepared, and electrical treeing experiments are implemented under alternating current (AC) voltage at 50, 70, and 90 °C. Experimental results show that with the incorporation of sPP increasing to 15 wt%, the inception time of electrical tree increases by 8.2%. The addition of sPP by 15% distinguishes an excellent performance in inhibiting electrical treeing, which benefits from the ability to promote the fractal dimension and lateral growth of branches. Further increase in sPP loading has a negative effect on the electrical treeing resistance of blended insulation. It is proved by DSC and POM that the addition of sPP promotes the heterogeneous crystallization the of PP matrix, resulting in an increasing density of interfacial regions between crystalline regions, which contains charge carrier traps. Charges injected from an electrode into a polymer are captured by deep traps at the interfacial regions, thus inhibiting the propagation of electrical tree. It is concluded that the modification of crystalline morphology by 15 wt% sPP addition has a great advantage in electrical treeing resistance for PP-based cable insulation.

scholarly journals Electrical Detection of Degradation in Specimens of HVDC Cable Insulation

Energies ◽  
2020 ◽  
Vol 13 (15) ◽  
pp. 3963
Author(s):  
Douglas Jutsell Nilsson ◽  
Stanislaw M. Gubanski ◽  
Yuriy V. Serdyuk
Keyword(s):  
Published Data ◽  
Cable Insulation ◽  
Isolation System ◽  
Service Environment ◽  
Injection Process ◽  
Electrical Tree ◽  
Metal Seal ◽  
Environmental Isolation ◽  
Inception Voltage ◽  
By Products

One of the challenges in laboratory investigation of degradation and ageing of HVDC cable insulation is related to securing, or in other words, imitating the real service environment of the material specimens. So far, the published data refer to experiments conducted in thermo-oxidative conditions, which is not the case during normal cable operation. In service, the cable insulation is protected by a metallic barrier that blocks the transfer of any substances in and out of the construction. By-products from the cross-linking reactions cannot diffuse out and any foreign substances are blocked from entering the insulation. Thus, in order to generate results that are valid, these conditions must be replicated in laboratory experiments. This contribution presents a methodology elaborated for performing ageing experiments in a hermetically sealed environment. Degradation of the material is evaluated through changes in the electrical tree inception voltage and test object capacitance over time. Securing the environmental isolation is accomplished with an isolation system consisting of a glass enclosure with attached metallic electrodes. Indium is used to create a glass-to-metal seal between the glass and the electrodes. The electrode geometry is of needle–plane type and the needle injection process is semi-automated to ensure specimen repeatability.

Electrical treeing behavior at high temperature in XLPE cable insulation samples

2015 ◽  
Vol 22 (5) ◽  
pp. 2841-2851 ◽  
Author(s):  
Xiangrong Chen ◽  
Yang Xu ◽  
Xiaolong Cao ◽  
S. M. Gubanski
Keyword(s):  
High Temperature ◽  
Cable Insulation ◽  
Xlpe Cable ◽  
Electrical Treeing

scholarly journals Electrical Treeing in Power Cable Insulation under Harmonics Superimposed on Unfiltered HVDC Voltages

Energies ◽  
2019 ◽  
Vol 12 (16) ◽  
pp. 3113 ◽  
Author(s):  
Mehrtash Azizian Fard ◽  
Mohamed Emad Farrag ◽  
Alistair Reid ◽  
Faris Al-Naemi
Keyword(s):  
Electric Fields ◽  
Direct Current ◽  
Asset Management ◽  
Diagnostic Techniques ◽  
Power Cable ◽  
Operational Parameters ◽  
Cable Insulation ◽  
Electrical Tree ◽  
Double Electrode ◽  
Electrical Trees

Insulation degradation is an irreversible phenomenon that can potentially lead to failure of power cable systems. This paper describes the results of an experimental investigation into the influence of direct current (DC) superimposed with harmonic voltages on both partial discharge (PD) activity and electrical tree (ET) phenomena within polymeric insulations. The test samples were prepared from a high voltage direct current (HVDC) cross linked polyethylene (XLPE) power cable. A double electrode arrangement was employed to produce divergent electric fields within the test samples that could possibly result in formation of electrical trees. The developed ETs were observed via an optical method and, at the same time, the emanating PD pulses were measured using conventional techniques. The results show a tenable relation between ETs, PD activities, and the level of harmonic voltages. An increase in harmonic levels has a marked effect on development of electrical trees as the firing angle increases, which also leads to higher activity of partial discharges. This study of the influencing operational parameters of HVDC converters on power cable insulation is predicted to contribute to enhancements in cable design and progressive advancement in condition monitoring and insulation diagnostic techniques that can lead to more effective asset management in HVDC systems.

scholarly journals Temperature Effect on Electrical Treeing and Partial Discharge Characteristics of Silicone Rubber-Based Nanocomposites

2015 ◽  
Vol 2015 ◽  
pp. 1-13 ◽  
Author(s):  
Mohd Hafizi Ahmad ◽  
Nouruddeen Bashir ◽  
Zolkafle Buntat ◽  
Yanuar Z. Arief ◽  
Abdul Azim Abd Jamil ◽  
...  
Keyword(s):  
Tree Growth ◽  
Silicone Rubber ◽  
Partial Discharge ◽  
Effect Of Temperature ◽  
Growth Time ◽  
Electrical Tree ◽  
Base Polymer ◽  
Increasing Temperature ◽  
Vulcanization Process ◽  
Electrical Treeing

This study investigated electrical treeing and its associated phase-resolved partial discharge (PD) activities in room-temperature, vulcanized silicone rubber/organomontmorillonite nanocomposite sample materials over a range of temperatures in order to assess the effect of temperature on different filler concentrations under AC voltage. The samples were prepared with three levels of nanofiller content: 0% by weight (wt), 1% by wt, and 3% by wt. The electrical treeing and PD activities of these samples were investigated at temperatures of 20°C, 40°C, and 60°C. The results show that the characteristics of the electrical tree changed with increasing temperature. The tree inception times decreased at 20°C due to space charge dynamics, and the tree growth time increased at 40°C due to the increase in the number of cross-link network structures caused by the vulcanization process. At 60°C, more enhanced and reinforced properties of the silicone rubber-based nanocomposite samples occurred. This led to an increase in electrical tree inception time and electrical tree growth time. However, the PD characteristics, particularly the mean phase angle of occurrence of the positive and negative discharge distributions, were insensitive to variations in temperature. This reflects an enhanced stability in the nanocomposite electrical properties compared with the base polymer.

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