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NTT has recently introduced state-of-the-art equipment to analyze your insulating fluids for metals at low concentration levels. As a result, significant price reductions are now available. As always, we provide rapid turnaround with NTT’s well-established QA/QC program.
Several methods exist for determining low concentrations of metals present in a liquid matrix such as transformer oil. Among them include electrochemical, nuclear-activation analysis, X-ray fluorescence, emission spectrometry, and atomic absorption spectroscopy (AA).
AA analysis depends on the selective absorption of descrete frequencies in the radiation spectrum by free metal atoms. During the analysis, an oil sample is burned, and the metals are turned into free metal atoms by this high-temperature incineration. During incineration, the instantaneous intensity of the radiation spectrum is measured and compared against standards to determine the presence and concentration of any free metal atoms. The most practical way to do this is to burn the oil sample in a high-temperature graphite furnace. The advantage of this method is that the oil sample can be place directly in a disposable graphite sample tube and burned in the tube without any further preparation and, more importantly, the detection levels of this method are better able to determine lower concentrations of metals. Another, less suitable method is to dilute the oil with hexane and then burn it.
|Aluminum||windings, corona shields, ceramic bushings|
|Copper||Windings, bronze & brass components|
|Iron||Core and tank|
|Lead, Tin, Silver, Zinc||Connectors, lugs, bolts and peripheral components|