Eaton SEFELEC 5 Series User Manual

User manual SEFELEC 5x Series 186 v1.06APPLICATION NOTESWHY DIELECTRIC TESTS ?The dielectric tests are performed in order:- to detect manufacturing fault on electrical equipment- to verify the quality of the insulating material of an electrical equipment- to verify that an electrical installation has been correctly done- to control the insulation resistance of an equipment or an installation to trace its changesduring the years.Dielectric tests consist of both insulation resistance measurements and dielectric strengthtestsGLOSSARY OF TERMS• LEAKAGE DISTANCE: The smallest required distance, measured on the surface of the insu-lating material, between 2 conductive parts, to avoid breakdown.• LEAKAGE CURRENT: Steady current flowing in an insulating material subject to high volt-age.• BREAKDOWN: The immediate break of the dielectric property of an insulating material. Eve-ry breakdown creates more or less damages to the insulating material. The breakdown testscan be therefore destructive or not.• INSULATION RESISTANCE: Characteristic of an insulating material that being subject to avoltage, shows a resistance such as the value of the leakage current which flows through itstays within acceptable limits.• DIELECTRIC STRENGTH: Ratio between the voltage at which a dielectric break of the insu-lating material occurs and the distance between the two points subject to the voltage (gener-ally given in kV/cm). Regarding the insulating material type (solid, liquid or gas) a dielectricbreak can be: a perforation, a flash over or an arc.