Question 159Electricity & Electronics - Assistant Engineer

The correct answer is D) kicking slightly downscale as voltage is applied. When testing insulation resistance with a megohmmeter, a slight downscale kick of the pointer as the test voltage is applied indicates current leakage along the surface of the insulation. This is due to the presence of moisture or contaminants on the insulation surface, which creates a conductive path for the test current, causing the pointer to initially dip before rising to the actual insulation resistance value. The other options are incorrect because: A) a continually rising pointer indicates good insulation without leakage; B) a dip towards zero then slow rise is indicative of poor or deteriorating insulation; and C) a constant resistance reading would suggest the insulation is not being affected by surface leakage.