What is the advantage of Pressure relief device in TELK type GT over explosion vent of BHEL, even though in both cases oil will be expelled out during sudden pressure rise?

What is the advantage of Pressure relief device in TELK type GT over e

1.	What is the advantage of Pressure relief device in TELK type GT over explosion vent of BHEL, even though in both cases oil will be expelled out during sudden pressure rise?
Answer» During internal fault, the internal pressure rise is relieved by the expelling out of oil through Pressure relief device /explosion vent. However the Pressure relief device closes back when the pressure drops. Hence the oil exposure to atmosphere is minimised, thus saving large quantity of costly transformer oil from oxidation and moisture absorption. Fire hazard due to transformer oil does not exist after the closure of Pressure relief device.