ANSI/IEEE C57.12.10 2

[jacphi]

with reference to the above standard,i have a 2500kva , 13.8kv,480v xfmr with power BIL. para 5.7.2 of ansi c57.12.10 states that a pressure vacuum bleeder is to be provided for XFMR rated 2500kva and above with power BIL. my transformer is sealed type. is the pressure/vacuum bleeder required for a sealed type transformer.

 

[busbar]

For 2500kVA or higher—it seems like, regardless of cooling rating, a bleeder is mandated correlated with BIL [Table 8.} Apparently the consensus is that characteristics like fault-gas volume may be too great for larger power ratings to permit the sealed-tank design as discussed in §5.7.1 for <2500kVA versions. There may be historic evidence that, above a particular size, potential for tank rupture is to great a risk without an integral pressure-relief valve.

 

[jacphi]

the xfmr does have a pressure relive device.but now the question is regarding the vacuum bleeder.what are the possibilities of a vacuum being created inside a sealed type transformer.

 

[busbar]

Offhand, I would think the manufacturer would design the tank to remain unaffected over some published ambient-temperature and load range. It may pay the get specific numbers from the manufacturer {either before or after procurement.}

 

[stevenal]

A pressure relief operation followed by load removal and cooling would cause this condition.