Answer / gunasekaran

as per standard it is not same cooling is depending upon
the rated MVA percentage impedance depending upon the MVA
rating if low MVA %impedance is low if high MVA %Z is high
in standard upto30MVA we can use ONAN
upto60MVA ONAF
above 60MVA we can use OFAF
upto 1.5MVA AN
if customer asking we can use for colling method for any
rating.

Answer / abhishek

according to property there are 2 types of xmer 1.step up
2.step down.but according to construction core type and
shell type.

Answer / satya dev

Imopedence is depending upon the core winding and rating
capacity, it is not depending upon the cooling system.

Answer / vamsi.n

COOLING SYSTEM OF THE TRAMFORMER IS DEPENDING UPON THE
CAPACITY AND DESIGN OF THE MANUFRATURER THER IS NO
TECHNICAL RELATION BETWEEN PERCENTAGE OF IMPEDENCE AND
COOLING SYSTEM, BUT PHYSICALLY ONAN IS USED FOR LOWER
CAPACITY TRANSFORMERS AND ONAF IS USED FOR HIGHER CAPACITY
TRANSFORMERS IN THAT WAY THE PERCENTAGE WILL DIFFER WITH
EACH OTHER

Answer / akr

yes percentage impedamce depandes on system voltage

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