SSIMS Molecular Selective Imaging: a new diagnostic tool to investigate metal passivators in scrapped transformers

In every high voltage grid, the replacement of assets is a slow but steady process that guarantees long-term reliability of the power distribution networks. The prioritisation of such interventions is based on complex rating criteria specifically designed to highlight potential issues of certain machines (or families of machines) in need of care. Given the tremendous costs of operations such as the replacement of a power transformer it is not surprising to observe constant efforts devoted to finding new and better monitoring and diagnostic tools. These are capable of delivering invaluable information about the conditions of a transformer, in service or after it is either failed or proactively scrapped, allowing a better comprehension of underlying chemical-physical phenomena occurring. Ideally, advanced monitoring and diagnostic tools should ultimately result in improved rating parameters to be applied in the evaluation of future interventions. This feasibility study evaluates the use of static secondary ion mass spectrometry (SSIMS) molecular selective imaging as a diagnostic tool for power transformer. SSIMS is herein demonstrated to be able to assess, without doubts, the presence and integrity of the passivation layer produced by Irgamet®39 on copper surfaces in laboratory tests. The technique has also been tested on real samples collected from one of the phases of a 400/275kV autotransformer proactively scrapped and proved to be applicable without significant sample preparation. The possibility of its use in the study of the distribution of Irgamet®39 across the windings is also demonstrated. Further development of SSIMS as a diagnostic tool would be significantly increasing the grade of detail at which scrapped/failed units could be inspected. A better understanding on how the operating conditions or the design of a transformer can affect the anticorrosion protection layer at the molecular level would open the way to significant ad hoc improvements of both operative guidelines and rating criteria for power transformers

Influences of parturition on home range and microhabitat use of female black-faced impalas

The use of home ranges and microhabitats by female black-faced impalas Aepyceros melampus petersi was investigated using radio-telemetry over a 4-month period that coincided with parturition at Ongava Game Reserve, north-west Namibia. The aim of the study was to test how ranging patterns and microhabitat use were affected by the presence of young. The mean minimum convex polygon (MCP) home range of the 11 tracked female black-faced impalas exceeded the largest of home ranges of impalas elsewhere by at least six times, and females used significantly larger total ranges (MCPs) after birth, although (50% kernel) core areas did not change significantly. Females were more likely to be solitary or alone with a lamb in the first week of their lambs' lives than in the periods after or before that time, and they both shifted their home ranges and changed their microhabitat use after parturition. Decisions on microhabitat and space use by female black-faced impalas appeared to be affected by parturition