Impulse Tests of Bushing
- Dry Lightning Impulse Voltage Withstand Test
- Dry or Wet Switching Impulse Voltage Withstand Test
Dry Lightning Impulse Voltage Withstand Test
- This test is applicable to all types of bushings.
- It is conducted as per I.S. 2071 (Part 2)-1976. The bushing is subjected to fifteen full wave impulse of positive polarity followed by fifteen full wave impulses of negative polarity of the standard wave form 1.2/50 us.
- The time intervals between consecutive applications of the voltage is sufficient to avoid effects from the previous application of voltage.
- The bushing is considered to have passed the test if no puncture occurs and if the number of flashover at either polarity does not execed two except for transformer bushings.
Dry or Wet Switching Impulse Voltage Withstand Test
- The bushing is subjected to fifteen impulses of positive polarity followed by fifteen impulses of negative polarity of the standard waveform 250/2500 us.
- The bushing is considered to have passed the test if no puncture occurs at either polarity and if the number of flashover at either polarity does not exceed two except the transformer bushings for which not more than two flashover at positive polarity and one flashover at negative polarity are permitted.