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Instrument for preparing reference material for dissolved gas analysis in transformer oils

The goal of the project is development and construction of the equipment for preparing the reference material for dissolved gas analysis used for prediction of faults in power transformers.

The aim of the project is to construct the instrument for preparing the house reference materials and “gas-in-oil standards”. For the prediction of incipient faults in oil insulated electrical instrument (transformer) the reference standard material for dissolved gas analysis is needed. Two methods are described in IEC 60567. The first is for preparing a large volume of gas in oil standard with the equipment used mercury, and the second is for small volume using syringes and stopcocks. There are few reference materials for dissolved gases in transformer oils available on the market. The problem is that reference materials (RM) for gas in oil are very expensive and their shell life is very short. Also there are no commercially available products that are accredited to the ISO guide 34 reference standard. Upon successful completion of this project a Transformer oil testing laboratory will have the option of preparing the reference materials to perform internal quality control of the dissolved gases in oils and/ or purchase standards accredited to ISO guide 34. Accredited standards will be preferred or even mandatory for laboratories accredited to ISO 17025. Transformer oils are used to insulate many power transformers and other electrical distribution instrument. They are disposed to ageing caused by electrical, mechanical, environmental and thermal stresses which can lead to fatal damages and faults. These faults can result in great cost not only for power transformers but also because of possible disintegration of distribution system of electricity. Moisture, acids, sludge and gases dissolved in transformer oils are known as degradation products of transformer oils owing to ageing. This is the reason that regular analysis of transformer oils is an extremely valuable preventative maintenance tool and in many instances is a mandatory requirement under health and safety legislation or insurance requirements. The analysis of transformer oils provides information about the oil and enables the detection of other potential problems, including contact arcing, ageing insulating paper and other possible faults. Under conditions of normal power transformer functioning, ageing can occur very slowly, but due to electrical and thermal faults, these processes can be accelerated. The transformer oils are exposed to chemical reactions that result in generation of soluble gases of hydrocarbon composition, like methane, ethane, ethylene, acetylene, propane and propene. Carbon monoxide, carbon dioxide, hydrogen, oxygen and nitrogen can also be present in transformer oils as a product of ageing. Concentration and gas rate generation are usually dependent on faults. The internal condition of the power transformer can be determined by dissolved gas analysis and thus the development of faults can be detected at an early stage. The new method of vacuum gas extraction of dissolved gases from oil works without use of elemental mercury, therefore eliminating the danger to health of the operator and the risk of environmental contamination. It is still fully compatible with existing methods of vacuum degassing. The dissolved gas in oil analysis (DGA) method is used for diagnostic of faults in power transformers. This is an effective and rather simple method that aims in predicting the life time of a power transformer. Analyses should be reliable, as accuracy of results is extremely important for accepting a decision about possible failures. The quality and accuracy of the results of content of different gases using DGA analysis depends on proper performance of the method. This can be achieved by standardization of the whole analytical procedureand can be achieved in two ways. Firstly using the instrumentation proposed by this project an in house reference standard can be created which can be used on a continuing basis for the calibration and system checks. In addition to this the second part of the project will allow for standards to be produced to which will be accredited to the ISO guide 34 standard. These will be fully validated standards which will be fully traceable to CRM’s and will be used for a definitive calibration on a periodic basis as determined by each laboratory.
Acronym: 
RMDGA
Project ID: 
6 779
Start date: 
01-07-2011
Project Duration: 
36months
Project costs: 
600 000.00€
Technological Area: 
Analytical Chemistry
Market Area: 
Lubricants and functional fluids

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