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keywords: UV Imaging systems, EPRI-USA, Generators, MOTORS, Insulation Degradation, Partial Discharge, Corona Dust, Voids, Electrical Loss


The process of generating electrical power from sources of primary energy such as heat, kinetic and nuclear energy is called power generation. In most electric power plants electricity is generated by electromechanical generators that are driven by heat engines fueled by chemical combustion of fossil fuel or nuclear fission, or by energy from flowing water and wind, and "green" energy sources such solar photovoltaics and geothermal power.

Turbines and generators are the main components in power plants which generate electricity. The turbine blades spin and rotate coils of wires within circular arrangements of magnets which result in the generation of electricity.

Corona is present in high voltage rotating electric machines. It is caused by electric field being high enough to locally break down the gas that is adjacent to the solid insulation. Industry statistics by IEEE and EPRI indicate that approximately 40% of all air-cooled high voltage motors and generates failures occur due to insulation. Supporting it, the survey of 1199 hydro generators carried out by the CIGRE study committee SC11, EG11.02 present the insulation damage as the main factor in hydro generators failure mechanism

Ofil's daytime corona cameras enable pinpointing sources of corona partial discharge and designate thereby faulty components and components in deteriorating stages.

The Benefits of Using DayCor® Corona cameras

  • Lower the risk of in-service failure
  • Increase overall safety within a plant
  • Extend the time between major outages by on line assessing the rotating machine's condition
  • Identify specific failure mechanisms to determine the appropriate corrective action prior to a forced outage
  • Ensuring the effectiveness of corrective maintenance, like cleaning and re-wedging by having "before" and "after" corona inspection visualized findings
  • Find problems on new machines that may still be under warranty


  • DayCor®Luminar - ideal for any workshop or laboratory refurbishing/rewinding/testing generators and motors due to its built-in wide and narrow fields of view
  • DayCor®Superb - with excellent past performance history in hundreds of substations worldwide
  • UVollé - a handy and affordable tool used by maintenance teams inspecting nearby components


  • Valuable expensive components
  • Indoors inspection in workshops and/or laboratories
  • Inspection of nearby objects