Laboratory for transformer oil analysis

The Chemical Laboratory of Centralna Energoremontna Baza EAD (CERB) is created to satisfy the needs of the company, related to input and output analysis of transformer oils during the repair works.

The laboratory’s mission is to offer a wide range of analyses, related to preventive maintenance of transformer for industrial clients, power plants, national electric distribution network facilities, and, thanks to the analysis results and feedback from the qualified personnel, to offer valuable information for the transformers’ condition. This results in cost savings for maintenance due to amortization of the equipment, increase in safety and unexpected outages are prevented. The routine analyses are obligatory for this type of facilities and they are required by insurance companies, so they decrease the insurance expenses. Based on those results, one can take the right decision for maintenance.


Transformer oil analysis is one of the most effective methods for control of the transformer’s condition, early diagnostics and prevention.

The laboratory is accredited with an accreditation scope – sampling and testing of transformer oils based on the following indicators:

  • Physio – chemical tests (appearance, color, voltage between phases, density, water content, breakdown voltage BDV), acid number, flash point, anilionic point and other tests), used for diagnostics of the oil’s condition ;
  • Dissolved gas analysis (hydrogen, oxygen, nitrogen, carbon monoxide, carbon dioxide, methane, ethane, ethylene, acetylene, propene, propane, propyne), through which we can diagnose all exploitational discrepancies in the transformer ;
  • Furan compounds (with mail test 2-Fal and possible tests Fol, 5- HMF, 2ACF, 5-MEF), for inspection of the condition of the winding’s insulation paper ;
  • PCB (polychlorinated biphenyls) and PAHs (polycyclic aromatic hydrocarbons) for evaluation of the oil’s toxicity ;
  • Corrosive Sulphur, in accordance with ASTM D1275-15, for presence or absence of very dangerous corrosive Sulphur compounds in the oil, that could corrode the copper in the windings ;
  • Dibenzyl disulfide, for identification and quantity evaluation of the main corrosive sulphur factor ;
  • Passivators for localization and quantity evaluation of the mail corrosive sulphur factor ;
  • Passivators for localization and quantity evaluation of additions, that cover the impact of the corrosive sulphur compounds ;
  • Heavy metals (iron, copper, zinc, etc.) which can diagnose the level or wear-out of the metal construction elements in the transformers ;
  • FTIR (Infrared spectroscopy with Fоurier transformation), which is a fingerprint of the oil, gives the structure of the oil and secondary products.
Other services

Mercury analyses Hg) for very low concentration (ppb) on any solid or liquid material; particles calculation for pollution evaluation as per NAS 1638 or ISO4406 from light fuels from distillate or hydraulic mineral oils; PCBs(polychlorinated biphenyls), for evaluation of the toxicity level in oils, fuels, soil, surfaces and other samples from the environment; dynamic viscosity (in accordance with the Brookfield method), in low temperatures, for transformer oils; air release (gas bubbles separation time – GBST), applies on hydraulic mineral oils; determination of CFPP (Cold Filter Plugging Point) for diesel fuels, for evaluation the fuel behavior in cold conditions, as well as many other tests for different types of lubricant and liquid or gas samples of fuels, as well as water and sewage samples.