PMC Conductors consist of copper wire and insulation parts to transport electricity. PMC insulators should have anti-pollution resistance and hydrophobicity resistance.
Several critical issues regarding the structural integrity of the next generation HV HT conductors based on PMC have been recently investigated in our laboratory. First of all, the effect of excessive bending loads generated either during manufacturing, transportation and/or installation on ACCC conductors was examined both numerically and experimentally.
As an example, internal stresses in the conductor core are shown in Fig. 1. This was accomplished by performing a non-linear bending/contact analysis. The most internally overstressed region of the rod under bending was found inside the carbon/epoxy section of the rod just near the carbon/glass fiber interface, on the compressive side of the rod. A clearly defined critical bend radius for the onset of damage of the current designs of the ACCC conductors has been found [16]. Bending ACCC rods over small mandrels, travelers, pins, etc. below the critical bend radius will generate compressive stresses in the rods high enough to cause fiber kinking and splitting affecting the structural integrity of the conductors in service.
Using the critical bend radius determined numerically and verified experimentally through our research, three catastrophic failures of the conductors which occurred in Poland in 2008 (Fig. 2) and an additional failure in the US were explained. Our explanations were reported to the transmission line community in 2010 (IEEE PES, Minnesota July 2010)
The effect of high cycle fatigue (HCF) on the conductor PMC composites has also been evaluated. This was done to determine life of the conductors as a function of the degradation rate of their PMC. HCF failures of the conductors occur in-service most commonly at mechanical connections, under relatively low frequency, and low magnitude vibrations called aeolian vibrations. The vibrations will generate cracks of various shapes and orientations in the glass/epoxy part of the composite (Fig. 3) depending on the magnitude of bending, and transverse compressive stresses caused by the sleeves.
The influence of HT and HV fields on the long term performance of the PMC conductors is a significant concern at present among potential users of the conductors. Therefore, the individual and combined effects of HT, ozone and atomic oxygen on HT epoxies and glass fiber/carbon fiber/HT epoxy composites is being investigated in our present research, both experimentally and numerically. As an example, the oxidation layer in a HT epoxy subjected to 1% ozone at 140°C and the three point bending strengths after aging in different aging condition are shown in Fig. 4.
It is hypothesized that a computational chemistry approaches, such as Gaussian or Molecular Dynamics, could be used to model the interaction between a cured HT epoxy resin and the presence of elevated temperature, atomic oxygen, and/or ozone to determine their resistance to oxidation under in-service conditions. For example, Gaussian 09 was used to find the most favorable bonding sites for atomic oxygen in DGEBA cured with EDA. The very reactive atomic oxygen atom can attach in many places. However, as expected, the most energetically favorable sites were where a lone pair was available to complete the valence shell on the atomic oxygen. These sites were either on the nitrogen site of EDA or on the aromatic carbon ring of the DGEBA (Fig. 5).
PMC Conductors can be used in transmission and distribution power systems, having damaging mechanical loading and transverse loading under Aeolian vibrations at mechanical connections.
Relative Articles:
Porcelain insulators,silicone rubber insulators
Silicone rubber insulators manufacturers in India
Composite silicone rubber insulators
Advantages silicone rubber insulators
Silicone rubber insulator property
©2014 Zhengzhou Orient Power Co., Ltd All rights reserved. Tel/Fax: +86 371 86097078
sales@composite-insulator.com Orient is a composite insulator manufacturer for products of composite insulator and polymer insulator
