Verifying Transformer Rating
Verifying Transformer Rating
(OP)
I have a power transformer marked
KVA = 2501/2800/3250/3500
Class ONAF
55/65 deg
Is it correct that the 2501/2800 are ratings at 55/65, no fans, and the 3250/3500 are 55/65 with fans?
KVA = 2501/2800/3250/3500
Class ONAF
55/65 deg
Is it correct that the 2501/2800 are ratings at 55/65, no fans, and the 3250/3500 are 55/65 with fans?






RE: Verifying Transformer Rating
RE: Verifying Transformer Rating
As to sizing - it depends. As long as the transformer is adequately protected and it is felt that the rating will not be exceeded, I be OK with one xfmr. Obviously a second transformer would allow for more flexible loading, greater reliability, and probably extend the life of both transformers, it would represent a major expense. I'd design the system so it can be added later.
RE: Verifying Transformer Rating
To confirm - you are indicating you'd consider tying both the existing and new generators (total output 3.2 MVA/0.8 pf) through the single, existing 3500 KVA transformer, provided protection was configured to ensure transformer ratings were not exceeded? This would end up decreasing the overall KVA/reactive capability of the facility, although in normal operation this should not be an issue. As the existing GSU and gear is already installed, designing for a future connection would also involve some expense. I am guessing the mgmt. will elect to leave the existing xfmr and interconnecting switchgear line up as is. I had envisioned a second or new, larger transformer.
RE: Verifying Transformer Rating
RE: Verifying Transformer Rating
RE: Verifying Transformer Rating
RE: Verifying Transformer Rating
when talking about genset ratings keep in mind that acc. to ISO 8528-1 'Application, ratings and performance' only 'Continuous Power (COP)'-rated genset are capable of delivering 100% of nameplate power on a 24/7 basis. Others like 'Prime Power (PRP)' usually are either limited to 70% on average over a 24-h-period or have limited running hours per year (500hrs at 100% for a 'Limited-Time running Power (LTP)'-rated genset). So except for COP-Operation the transformer may be downsized w/o compromising its life expectancy.
Load factors may also be different between manufacturers and deviate from the ISO standard.
Johannes
RE: Verifying Transformer Rating
RE: Verifying Transformer Rating