what is onan, onaf, ofan, ofaf in transformer?

Answer Posted / mehedi islam aneek

The first letter designates the internal cooling medium in
contact with the windings.

O= mineral oil or synthetic insulation fluid with a fire
point ≤ 300°C
K = insulating fluid with a fire point > 300°C
L = insulating liquid with no me3asurable fire point.



The second letter designates the circulation mechanism for
internal cooling medium

N = Natural convection flow through cooling equipment
and in windings
F = Forced circulation through cooling equipment and
natural convention flow in the windings (also called
"directed flow")
D = Forced circulation through cooling equipment,
directed from the cooling equipment into at least the main
windings



The third letter designates external cooling medium

A = Air
W = Water



The fourth letter designates the circulation mechanism for
the external cooling medium.

N = Natural convection
F = Forced circulation (Fans (air cooling) , pumps
(water cooling))



For example: ONAN designates an oil filled unit that has
natural convection flow in the tank and utilizes natural air
convection cooling externally.



If this transformer has fans added for forced air
externally, the designation would be ONAF.



A transformer that has natural convection cooling as a base
rating and an elevated rating when fans were added later,
would be designated as ONAN/ONAF.



High fire point fluids use the designation of "K" for fluid
type. Thus a naturally cooled high fire point fluid would be
KNAN and the same unit with fans would be KNAF.

Is This Answer Correct ?    44 Yes 3 No



Post New Answer       View All Answers


Please Help Members By Posting Answers For Below Questions

Explain the operation principle, advantages and disadvantages of the following converters: a) A 12 pulse converter b) A Switch-mode inverter c) A thyristor inverter

1498


How to calculate mf when meter equipment and meter are connected

1275


What will happen if a dc source is given to a tubelight. Will it work or wont it work....

1494


Why neutral point is consider as zero potential?

2043


diff b/w elcb and rccb

1844






IF I KNOW THE AREA OF CROSS SECTION OFTHE WIRE , WATTAGE OF THE LOAD ,VOLTAGE SUPPLY WHAT IM GIVING TO THE LOAD AND ALSO POWER FACTOR OF LOAD ....... SO GIVE ME FOR WHAT AMOUNT OF CURRENT I SHOULD USE WHICH TYPE OF CABLE?

1436


wow to calculate the transformer rating(KVA)

1685


what is the current setting for different relay protection for transformer .

1760


what is mean by dry frequency

1945


What is precision of a measurement?

678


what is mean by restructuring power system?

1552


Explain the process of commutation in a dc machine.

609


What aturn on methods of scr?

711


when the time of backcharging the transformer three phases only enough or three phase with neutral is must.from these which one is the best one.

1583


Define unilateral circuit?

707