Sunday, 27 June 2021

Explosion vent, PRV of transformer and their difference

 See this content in form of Youtube video: https://youtu.be/B0mepIWyWEQ


What is Explosion vent


  • As the name suggests it is part of transformer which prevents explosion of transformer tank and give path to oil for coming out of tank when it's pressure increases

  • One type of Mechanical Protection

  • Upper side bent shape pipe connected from main tank to outside atmosphere 

  • Consists aluminium diaphragm at both ends of pipe with wire mesh

  • Diaphragm provided for prevention of moisture and dust particles inside main tank

  • Wire mesh provided to prevent entry of diaphragm inside transformer tank


What is PRV


  • Full form is pressure relief valve

  • As the name suggests it is valve that relieve excess pressure

  • One type of mechanical protection

  • Round shape valve mounted on top of transformer tank with spring mechanism


Why we use explosion vent and PRV


  • To prevent explosion in case of high pressure inside transformer tank thereby preventing damage to transformer

  • Equipment safety

  • Manpower safety

  • We get NO and NC contact in PRV so that we can trip circuit breaker of transformer when PRV operates


How it works 


  • Gas forms from oil when heavy short circuit inside tank

  • This creates pressure inside tank

  • This pressure need to release somehow otherwise tank will explode

  • This pressure breaks diaphragm of explosion vent and give path to oil and gas

  • Diaphragm breaks if inside tank pressure is more than 5 PSI or 0.35 kg/cm2

  • PRV operates if inside tank pressure is more than 0.49 Kg/cm2 or as per demand


How to observe


  • Glass window is provided on pipe of explosion vent to check oil level

  • Mounted pin rises upward when PRV operate



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