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ANALYSIS OF TRANSFORMER OIL

Breakdown voltage

The breakdown voltage is important as a measure of the oil's ability to withstand electrical stresses. This analysis determines the voltage threshold at which the dielectric oil breakdown occurs when it is subjected to an electric field.

Moisture content

Consist of measuring the moisture content of dielectric oil to prevent associated risks. In fact water molecules are capable of carrying an electrical charge and, if enough are present, electricity will “leap” across the molecules causing “arcing”. Unwanted movement of electricity inside the transformer causes damage and can be critical, leading to power shutdown.

Neutralization number (acid content)

Measures the degree of acidity of the dielectric oil which correlates to its level of degradation. An acidic transformer oil is prone to causing corrosion of metallic parts. The rate of increase of the transformer oil's acidity is a good indicator of its aging rate. The acidity level is used as a general guide to determine when to replace or regenerate (process) the oil.

Colorimetry and appearance

This analysis determines the clarity and the presence of abnormal or foreign compounds in the oil. This test highlights the aging of the oil.

Analysis of dissolved gases

This analysis quantifies all the gases created by the degradation of the dielectric oil. Through the presence and the relationship between the dissolved gases in the transformer oil, it is possible to identify, for example, a hot spot, an electric arc or an atypical degradation of the cellulosic insulation, which could lead to a preventive intervention on the transformer in order to avoid breakdowns and costly machine downtime. The dissolved gases are:

H2 (hydrogen),
O2 (oxygen),
N2 (nitrogen),
CH4 (methane),
CO (carbon monoxide),
CO2 (carbon dioxide),
C2H4 (ethylene),
C2 H6 (ethane),
C2H2 (acetylene).

Analysis of furanic compounds

Furanic compounds are produced when the insulating properties of the cellulose paper deteriorate. Measuring the concentration of these compounds makes it possible to estimate the degradation and the residual lifetime of the cellulosic insulation of the transformer.

PCB analysis (Polychlorinated Biphenyls)

This analysis allows to determine the level of pollution of the transformer oil. The PCBs are carcinogenic components to avoid in the transformer oil.

Corrosive sulfur compounds

Sulfur compounds present in the oil can lead to the corrosiveness of the transformer oil.

Tangent of Delta (Tan Delta)

The dielectric dissipation factor, which is a dimensionless quantity, is directly related to the resistivity and the permittivity in alternating voltage of a dielectric fluid. A measurement of the transformer oil's resistivity is also considered to be an important parameter for monitoring oils in service, as its values have been found to be a reasonably proportional to oxidative acids and to be affected by unwanted contaminants such as metal salts and water in the transformer oil.

Additional testing and services

Transformer oil processing (treatment)
Metals and particles counting
Viscosity
Fourier Transform Infrared spectroscopy analysis (FT-IR)
Spectrometry
Conductivity
Density

CONSULTING, MAINTENANCE, SALES AND OTHER SERVICES

Our additional services and competences include:

HTA and HTB electrical work
Overhaul, inspection and maintenance of power transformers and distribution (submerged or dry transformer)
In-depth expertise of transformers
Standard electrical measurements (insulation, transformation ratio, magnetizing current, no-load tests, short-circuit, etc.)
Advanced electrical measurements (Tan Delta, SFRA, IDAX, etc.)

Maintenance, diagnosis and repair of ABB type On-load Tapchanger (UB, UZ, UC) and type MR (V, M, MS…)
Sale of electrical equipment and accessories for transformers and others
Supply of electrical measuring devices and maintenance equipment (treatment machine, tank, pump, crane, etc.)
Sale of transformer oil

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