(13) Corona and RIV test
Test Method : Corona measurement shall be made in a dark laboratory. The voltage shall be increased until corona occur. The voltage level shell be recorded and then increase further up to 10-20% higher than corona on-set voltage and keep constant for 1 minute and then the voltage shall be reduced slowly while visual corona just disappears from the conductor bundle, until the bundle as a whole is free from visual corona. These levels shell be photographed with a minimum 1 minute time exposure, and voltage maintained for a minimum of 5 minutes to be sure that the discharge do not occur at this voltage level. RIV measurement shall be carried out at frequency of 1 MHz with a corona meter reading in pV. The test circuit was calibrated with a pulse generator providing electrical discharges of 50 pC. Radio Influence Voltage across measuring impedance of 100 ohms at each applied voltage is measured. The RIV measured at voltage which are increased from 200 kV to a voltage higher than 120% of phase voltage and then decreased to 200 kV.
Remark : (1) For testing galvanized steel strand of 1272 MCM ACSR/GA, 477 MCM ACSR/GA "HAWK"
and 795 MCM ACSR/GA
(2) Additional testing for 1272 MCM ACSR/GA (Item No. B2-1)