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Cherney E.,7 Woodland Glen Drive | Marzinotto M.,TERNA S.p.A | Gorur R.,Arizona State University | Ramirez I.,Electric Research Institute of Mexico | And 3 more authors.
IEEE Transactions on Dielectrics and Electrical Insulation | Year: 2014

The paper provides several methods to assess the condition of RTV coated porcelain/toughened glass insulators in the field. Visual observations of arcing and audible corona are the first indications that signal changes to the coating have taken place. It emphasizes that in the absence of reliable data one can use observations based on hydrophobicity to evaluate when maintenance or replacement of the coated insulators is necessary. Life extension strategies are suggested. It also demonstrates that there are differences in the hydrophobicity characteristics among commercially available coatings, and these can be quantified using standard laboratory techniques. Field experience suggests that the life of the RTV coatings can exceed 10 years even under the severest conditions of pollution. © 2014 IEEE. Source


Cherney E.A.,7 Woodland Glen Drive
IEEE Electrical Insulation Magazine | Year: 2013

A review of the literature on nanotechnology for the electrical power sector shows considerable hype in the technology, but the actual usage of nanomaterials in the sector is far below other industries. As an example, the automotive industry has made great strides in using nanomaterials because of their lower weight and higher physical strength. There are several reasons for this, the obvious one being the quantity of nanodielectrics is relatively small compared to nanomaterials in other industries. The second reason is that although there are clear improvements in some dielectric properties, for example resistance to partial discharges, the improvements in other properties are not so significant, or sometimes not even evident. Uniform dispersion of nano-sized inorganic fillers in nanodielectrics during manufacture is critical for repeatable electrical properties improvements, and this has been a problem in some of the reported properties such as breakdown strength. This comes about due to the fact that nanoparticles agglomerate easily because of the high surface energy, and conventional mixing techniques do not break apart the nanoparticle agglomerates. Another problem is the incompatibility of hydrophilic nanoparticles with hydrophobic polymers, such as silicone rubber, which results in poor interfacial interactions. © 2006 IEEE. Source


Cherney E.,7 Woodland Glen Drive | Fleming R.,7 Glenview Court | Gleichman G.,FASS
IEEE Electrical Insulation Magazine | Year: 2013

The first article in this issue is Partial Discharge Diagnostics: From Apparatus Monitoring to Smart Grid Assessment by Giancarlo Montanari and Andrea Cavallini, University of Bologna, Italy. It is the third in a series of reviews to be published in the Magazine to mark the 50th anniversary of DEIS. In it common knowledge of partial discharge mechanisms and measurements is reviewed, in order to explain why application of this powerful diagnostic technology has not been as widespread as might be expected. Condition-based maintenance of electrical apparatus based on PD detection has been moving toward on-line measurements for at least the last 20 years. So why is there still considerable activity in off-line PD testing today, probably even more than in on-line testing? The answer is straightforward: offline measurements offer the possibility of reduced noise, whereas on-line measurements may be severely affected by noise and disturbance from electrical apparatus other than that under test. Noise and disturbance rejection is essential for greater acceptability of on-line PD detection. The authors discuss some of the methods which have been proposed recently for noise rejection, based on time-of-flight techniques or on decomposition of the acquired PD pulse waveforms. Identification of the type of defect responsible for a given PD pattern is another important task, at present usually carried out by experts. However, this approach is incompatible with on-line, conditionbased-maintenance practices, because of the very large data stream generated by on-line monitoring, and the likely scarcity of experts. Thus efforts are being made to develop artificial intelligence tools, such as fuzzy logic or neural networks. © 2006 IEEE. Source


Fleming R.,7 Glenview Court | Cherney E.A.,7 Woodland Glen Drive
IEEE Electrical Insulation Magazine | Year: 2015

The first article in this issue is «The Effect of the Marine Environment on the Stator Insulation System of an Offshore Wind Turbine Generator» by Xuezhong Liu and colleagues from Xi'an Jiaotong University and Xiangtan Electric Manufacturing Co. Ltd., China. Compared with onshore wind farms, offshore wind farms have several advantages, e.g., the offshore wind speed is larger and more uniform, leading to greater wind power capacity and fewer turbulence effects, and, provided an offshore wind farm is located sufficiently far from the shore, visual impact, noise production, and shadow castcasting are less likely to be of public concern. However, the higher costs of foundation construction, more demanding technical requirements for wind turbine design such as anticorrosion, remote monitoring and controlling, and design considerations arising from operating in a hostile environment add to the complexity and cost. In order to simulate the influence of a marine environment on the insulation systems of a wind turbine generator (WTG), appropriate test conditions were replicated and a model stator of a 5-MW offshore WTG was tested. Testing involved temperature cycling between -30 and +100°C, maintaining constant temperature and humidity in the test chamber, and exposure to salt mist. In particular, the impact of the marine environment on the performance of the WTG insulation system was investigated by making nondestructive measurements of dissipation factor, DC insulation resistance, polarization index, and partial discharge inception voltage. These measurements were made before and after drying the specimens in an oven at 55°C for two hours. It was found that the dissipation factor and DC insulation resistance, degraded following exposure to the marine environment, recovered partially after drying. © 2006 IEEE. Source


Marzinotto M.,TERNA S.p.A | Cherney E.A.,7 Woodland Glen Drive | Mazzanti G.,University of Bologna
Annual Report - Conference on Electrical Insulation and Dielectric Phenomena, CEIDP | Year: 2015

This paper describes TERNA's experience over more than one decade of service of RTV coated toughened glass cap-and-pin insulators in AC lines. The installation of almost one million units and laboratory tests for the continuous monitoring of samples taken from the field have enabled promising estimates of the coating end-of-life and have increased remarkably the confidence about their reliability. In addition, trial installations of pre-coated insulators on DC lines have provided interesting results for the use of RTV coated insulators in HVDC overhead lines. Some considerations on the application of RTV half-coated cap-and-pin toughened glass insulators are also made. © 2015 IEEE. Source

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