Water in transformer (paper/oil)

Moisture greatly effects the life expectancy of an electric transformer: it not only deteriorates the dielectric properties of insulating materials (paper and oil) but also reduces the resistance to oxidation (aging) and the mechanical strength of the paper. That is why it is recommended to maintain moisture levels of the insulating system to a minimum. Description and functioning principle TheRead more

Essentially water within a transformer derives from two sources; either external, due to a damp environment or internal, due to thermal deterioration of the papers (hydrolysis).Therefore water can be dissolved within the oil or, more seriously, be absorbed into the solid isolation (papers) with an increasing probability of thermal damage, and bubble formation moving on to partial, low energy (D1)Read more

Insulating oil within electrical equipment in operation is subject to deterioration/contamination, mainly because of the surrounding conditions. This contamination continuously reduces the dielectric properties of the fluid thereby increasing the probability of failure. The physical treatment (also called physical decontamination) of oil, a more beneficial process than replacing it, aims to eliminate any contaminants in the insulating liquid (water, solidRead more

Sea Marconi has developed the Deosvision service for analysis and diagnosis, which is aimed at preventing the catastrophical failure of electrical equipment linked to critical issues, In fact, it is very similar to what happens in clinical diagnostics, as one can monitor the health status of the transformer by analyzing a sample of oil taken from it and then makeRead more

Sampling of oil, and even more so of papers, must be carried out by qualified operators according to protocols and procedures laboratory analyses must be carried out using methods set by reference standards, as guaranteed by accredited laboratories actions to prevent the "Water in the transformer (paper and oil)" criticality, namely the dehumidification and internal transformer inspections must be carriedRead more

For the definition of action priorities and choice of countermeasures, it is necessary to diagnose whether the criticality originates internally (paper degradation) or externally (atmospheric influences). If the origin of the moisture is internal (degradation of paper and oil) the countermeasures are: Physical treatment, Physical treatment, in the first instance to be performed off-load and subsequently on-load (transformer under load).Read more

The presence of water in the paper and oil system inside the transformer can be an extremely critical condition, especially when the criticality reaches an "extremely wet insulation" level (Table A1, IEC 60422, page 42), causing unreasonable risks of electrical failure. Table A.1 – Guidelines for interpreting data expressed in per cent saturation – IEC 60422 ed. 4-2013 This conditionRead more

For diagnosis of the the "Water in the transformer (paper or oil)" criticality, Sea Marconi uses its own diagnostic metrics, namely: visual signs on the transformer (and those from any internal inspection) are interpreted; through analysis of the oil and papers (if available following internal inspection) the symptoms are identified and co-factors evaluated. One of these is undoubtedly the temperature,Read more

Symptoms (analysis) The specific symptom of the "Water in the transformer (paper and oil)" criticality is related to the presence of the following diagnostic indicators with typical values not compliant with those recommended by the IEC 60422 standard: Water in oil (IEC 60814) To these are added diagnostic indicators derived from insulating paper analysis (following any internal inspection and sampling):Read more

Signs (visual inspection) Oil* affected by the "Water in the transformer (paper and oil)" criticality can have different characteristic aspects. *here we mean the sample of oil representative of the total mass of fluid present in the transformer casing. To do this, it is necessary to take the sample at the bottom of the transformer casing. In the presence ofRead more