(ii) Visual critical voltage. It is the minimum phase-neutral voltage at which corona glow appears all along the line conductors. It has been seen that in case of parallel conductors, the corona glow does not begin at the disruptive voltage but at a higher voltage called The Vc Vv, visual critical voltage. effective value of visual critical voltage is given by the following empirical formula : where is another irregularity factor having a value of 1·0 for polished conductors and mV 0·72 to 0·82 for rough conductors.
(ii) Visual critical voltage. It is the minimum phase-neutral voltage at which corona glow appears all along the line conductors. It has been seen that in case of parallel conductors, the corona glow does not begin at the disruptive voltage Vc but at a higher voltage Vv, called visual critical voltage. The effective value of visual critical voltage is given by the following empirical formula : where mV is another irregularity factor having a value of 1·0 for polished conductors and 0·72 to 0·82 for rough conductors.
18-DISRUPTIVE-AND-VISUAL-CRITICAL-VOLTAGES.docx