CBM Engineering provides diagnostics of transformer and lubricating oils according to the most important characteristics in the proper laboratory conditions. This is necessary for identification of potential defects in operating transformers and oils.
Sampling is carried out in the laboratory in full accordance with the requirements of IEC 60475-2014, IEC 60567-2005 and RD 34.46.303-98. All tests are carried out with high accuracy and compliance with the necessary safety measures. Our staff adheres to all principles in accordance with environmental laws.
- Compliance with international standards: CBM Engineering laboratory fully meets the requirements of the international standard ISO / IEC 17025-2017
- Proven quality level: CBM Engineering is certified according to ISO 9001: 2015, which indicates the presence of a quality management system
- Work with high voltage equipment: CBM Engineering deals with the diagnosis of high-voltage equipment, including transformers. Knowledge of the quality of transformer oils is an essential part of the correct diagnosis.
- Modern precision equipment: The laboratory is equipped with high-precision equipment that strictly passes calibration at periodic intervals.
- Qualified staff: The staff responsible for conducting the tests and obtaining reliable results consists of qualified specialists.
Determination of breakdown voltage
Breakdown voltage characterizes the ability of the oil to withstand electrical voltage without breakdown, this ensures trouble-free operation of the entire transformer isolation system. Therefore it should be periodically diagnosed. Analysis method: This parameter with a known standard deviation and coefficient of variation is determined on the automatic installation, specially designed for the oil testing.
Determination of tan delta
Tan delta (power factor) indicates the dielectric losses of the oil, or energy that is dissipated as heat, in the presence of impurities (polar components, gummy matter, etc.).
For transformer oil in service power factor can send signal earlier than other indexes.
Analysis method: The test is carried out on the apparatus, which allows measuring dielectric losses and the capacity of liquid dielectrics simultaneously in three cells. It helps to reduce the variability of the obtained results.
Determination of the content of furan derivatives
The content of furan compounds in the composition of transformer oils provides information on the state of paper insulation inside the equipment.This is due to a good correlation of the content of
these components with the degree of polymerization of the paper material.
Analysis method: To conduct this test, the above-mentioned gas chromatograph is used.
Determination of mechanical impurities
The content of mechanical impurities is one of the main factors affecting the performance
properties of transformer oils. Mechanical impurities include fibers, dust, products of
dissolution in oil of components of transformer parts (varnishes, paints, etc.). Some impurities
appear in the oil after damage to the transformer.
Analysis method: Under appropriate conditions, all mechanical impurities contained in the oil sample are isolated in accordance with GOST 6370-83, then their quantitative content is determined. For a qualitative analysis and particle size distribution, we also use the method of counting them on the surface of a membrane filter using an optical microscope.
Determination of flash point
Flash point is one of the most important characteristics of insulating oils, since this is a parameter that indicates
their flammability and helps to prevent possible emergency situations
Analysis method: The determination of this value is carried out in a closed crucible of the semi-automatic apparatus.
Determination of antioxidant (ionol) content
Additives in oils are continuously consumed during operation. When the antioxidant additive content drops to 0.1%, the process of intensive aging of the oil begins.
For this reason, it is important to control the content of the additive.
Analysis method: In the laboratory of our company, the conditions for the correct and reliable determination of the antioxidant additive (ionol) content by the chromatographic method on a gas chromatograph have been implemented.
Determination of water-soluble acids and alkalis
Water-soluble acids and alkalis are aggressive compounds that cause corrosion of metals.
Analysis method: Using a high-precision pH meter, we determine the pH value of the aqueous extract obtained by extracting the compounds to be determined from the oil.
Determination of viscosity
Viscosity, or the thickness of the oil, is important because it determines the lubricant's film strength and efficiency in preventing friction between moving parts.
Analysis method: The viscosity is determined using a capillary viscometer. The essence of the method consists in measuring the expiration time of a certain volume of liquid under the action of gravity through a viscometer.
Calculation of hydrocarbon composition
Based on the results of some tests (density, viscosity, refractive index), our laboratory calculates the hydrocarbon composition of the oil (the content of aromatic, paraffinic, naphthenic hydrocarbons) according to the method described in the international standard ASTM D2140-08.
Determination of acidity
Acidity characterizes the degree of purification from naphthenic acids, which cause corrosion of equipment. In addition,
the interaction of acids with metals forms salts that reduce the resistance of oils to oxidation and adversely affect its dielectric strength.
Analysis method: The essence of the method for determining the acidity is to titrate the acid compounds of the test product with an alcohol solution of potassium hydroxide in the presence of a color indicator.
Diagnostic methods for physical characteristics: Determination of density
Oil density is one of the fundamental physical properties. It shall be controlled low enough to effectively prevent floating ice in oil under cold climate, which can cause transformer
failure if the transformer is energized. Analysis method: The essence of the method consists in immersion of the hydrometer in oil, taking readings on the hydrometer scale at
room temperature and recalculating the results for density at a temperature of 20°C.
Analysis method: The essence of the method consists in immersion of the hydrometer in oil, taking readings on the hydrometer scale at room temperature and recalculating the results for density at a temperature of 20°C.
Determination of color
Color is the simplest indicator that allows you to make first assumptions about the quality of the oil. Color is the simplest indicator that allows you to make first assumptions about the quality of the oil.
Analysis method: In our laboratory this parameter is determined using the reliable color comparator according to ASTM D1500 standard with obtaining results on the scale of the same name. The color of lubricating oils is determined according to the same standard and on the same color comparator as transformer oils with obtaining results on the ASTM scale.
Determination of refractive index
Transformer oils are characterized by a certain constancy of physicochemical properties, including the refractive index.
This value allows you to calculate the hydrocarbon composition of the oils.
Analysis method: Refractive index is determined on a modern high-precision refractometer.
Determination of kinematic and dynamic viscosity
Proper high-temperature viscosity can ensure ideal effect of cooling and heat dispersion of transformer oil during long time service,
while proper low-temperature viscosity can ensure working safety of lowest cold start of transformer.
Analysis method: The kinematic and dynamic viscosity is determined using a capillary viscometer. The essence of the method consists in measuring the expiration time of a certain volume of liquid under the action of gravity through a viscometer.
Dissolved gas analysis (DGA)
DGA can provide insights into thermal and electrical stresses sustained by oil-immersed power transformers. It can help prevent further damage.
To compare the results in order to assess their reliability, DGA is also carried out on the alternative device.
Analysis method: The chromatographic method is used to determine the content of gases (H2, CO, CO2, CH4, C2H6, C2H4, C2H2, N2, 02) dissolved in oil. For this purpose, we use the automated gas chromatograph with a built-in flame ionization detector (FID) and a thermal conductivity detector (TCD) or katharometer. The modern device used in our testing laboratory, operating on the principle of photoacoustic spectroscopy, determines the concentration of compounds such as hydrogen, methane, ethane, ethylene, acetylene, carbon monoxide and carbon dioxide.
Determination of water content
The water content in the transformer oil, which accumulates as a result of its aging, negatively affects the properties, since even its small amounts significantly reduce the breakdown voltage of the oil.
Gradual waterlogging can lead to an accident with the irretrievable loss of expensive equipment.
Analysis method: Water detection is analyzed using the coulometric device for Karl Fischer titration according to IEC 60814-2013. The device has high accuracy and allows you to determine even 1 ppm of water in the analyzed oil sample. To compare the results and thereby ensure the highest accuracy, the analysis of water content is also carried out by a chromatographic method. Water from transformer oil is extracted with acetonitrile, and the resulting extract is analyzed on a gas chromatograph with a thermal conductivity detector.
Determination of sludge content
Determining the presence of sludge is an important test, as it allows you to identify the presence of deep aging products dissolved in oil that can precipitate in the active part
of electrical equipment. Precipitated aging products have the most negative effect on solid insulation.
Analysis method: The method consists in diluting oil with n-heptane and separating the sludge soluble in it.
Determination of interfacial tension
To measure interfacial tension of transformer oil in service is effective method for checking whether there is soluble polar impurities in oil resulted from aging.
Analysis method: The determination of this parameter in our laboratory is carried out by the ring method according to ASTM D 971-20. The advantage of this analysis is the ability to determine even a small amount of dissolved polar contaminants or oxidation products.