Over 20 years of experience in power sector! Technical expertise & refurbishing offered to hundreds of large power transformers and primary equipment of 110-750 kV! NOVA INDUSTRIAL S.A. was the official consultant of CNTEE Transelectrica, for the period 2015-2018, in the field of “Power Stations”, for the second consecutive time after the period 2011 – 2014! Our know-how, for your safety !

Power transformers and shunt reactors prophylaxis

1. Maintenance and diagnosis service

S.C. NOVA INDUSTRIAL S.A. evaluates the technical state of the power / distribution transformers and shunt reactors based on the analyze of the history data (concerning construction, factory tests, transport, substation erecting, tests for putting into service or for preventive maintenance, incidents in operation, etc.), in addition to diagnoses tests and measurements specific to each type of transformer or shunt reactor:

  • measurement of the winding resistance;
  • measurement of the windings insulation resistance (R15 and R60) and assessment of the absorption factor;
  • measurement of the dissipation factor (tg) and of the capacitance of the winding insulation system (between windings and between windings and earth);
  • measurement of the insulation resistance (R60), dissipation factor and capacitance of the main insulation (RC1, C1 and tgC1) and of the test tap insulation (RC2, C2 and tgC2) for condenser type bushings;
  • measurement of the insulation resistance (R60) and of the winding resistance, test of the insulation using power-frequency voltage, as well as assessment of the magnetization curve (for current instrument transformers included on the bushings);
  • measurement of the insulation resistance of the magnetic core: between core end earth, between sheet packs, between scaffolds, between scaffolds and earth;
  • assessment of oil contamination level (using analysis of dissolved gases, water content, particle content, resistivity, dissipation factor, electric strength voltage, insoluble sludge, interfacial tension, neutralization value, furanic compound content, anti-oxidant inhibitor content, etc.);
  • assessment of the mechanical condition of the power transformers and shunt reactors (evaluation of the mechanical distortion of the windings), using the low voltage impulse method and the frequency response analysis method;
  • infrared investigation for early identification of potential problems, without direct contact or interference with the power transformers or shunt reactors in operation;
  • other special tests (for example diagnosis tests using the recovery voltage method).

2. Technical specifications realization, bidder’s documentation analysis and offers evaluations for bids regarding the acquisition of power transformers and shunt reactors, as well as for modernizing or repairing activities for those already in place.

3. Technical assistance for the acquisition and the supplier / factory reception; technical assistance for the erecting, putting into service, repairing and maintenance activities.

4. Incident and Faulty analyses.

5. Specific technologies for the on-site refurbishing of the power transformers and shunt reactors; project management and technical coordination of these specific works.

6. Engineering activities referring to the diagnosis expert systems, the on-line or/and off line monitoring systems, databases realizations, interpretations of the analysis and/ or tests results made during the maintenance activities.

7. Purchase of special materials or equipment necessary for maintenance activities.

8. Other consulting activities requested by energy companies and not only.

Power transformers and shunt reactors prophylaxis