yes certainly be used as out put from secondary

during the design of power transformer,or any distribution
tfr the load current is taken into account ,and the windings
of the secondary side are accordingly designed that is the
load currents it can sustain ,insulation and cooling system
are taken into consideration...
suppose in your designing u r designed the windings to
sustain a 30 amp load current while reversing the windings
and taking the out put from primary as u stated, the load
current will be decreased at the 415 voltage side and the
current in the 220 voltage ll be increased to a factor of
transformation ratio as it has to work in same power..so the
windings of the 220 side may burnt out..if its not capable
of sustaining the increased current.

See transformer mainly used for step up purpose are of the
detal-star connection,the advantage is that in the seconary
for step up the insulation req is lessa s the voltage is
57.7 of actual vaue in secondary.So consdier ur question
now? is it advantageous.Transformer designs are done not
merely on load,but the winding
insulation,oil,insulation,cooling,etc are also important.

ok we can used as a step up transformer,but temprature of 
the transformer may be high.

it is impossible
primary is a primary ,secondary is a secondary
1 is not equal to 2
2 is not equal to 1
u know the matter first ok

sunil r u an ELECTRICAL ENGINEER? WHAT AN AMAZING ANSWER

ideally we can use. but practically there are limitations to
use. as the reasons are given in answer 2

its not possible,the while designing the the transformer we 
should calculate the capacity of load,according to the 
load  the insulation level oil level be designed,so its not 
possible one..

Dear Mr Akialok,

I think, the answer what you have given is not completely 
right.As the VA ratting is not going to change in the 
transformer, the max current in primmary & secondary will 
remain same in whatever way you use.
For example: For 1 KVA 220 V to 110 V trafo, Max primary 
current I1=1000/220 = 4.55 A & Max Seconday current 
I2=1000/110 = 9.09 A.
So even if you reverse the source voltage, in any way you 
can not use for more power.
Please reply for clarification.
Sadananda

I THINK ANSWER # 9 IS ABSOLUTELY CORRECT

We can use the step-down tansformer as step-up transformer. 
Secondary of the Transformer can be used as Primary. I am 
using it since last five years. I have no problem. Our 
Transformer was Step-Down , 2400/440V which was ordered by 
mistake. Actually we were in need of 440/2400V. So we 
connected the same Step down transformer as step-up 
transformer and it's working pefect.

mr Manoj. are u saying currectly.
if yes then i agree with u

Actually when transformer is manufactured  winding
insulation have major role.That is the number of
turn,insulation strength
and many other factor does remain same in both
winding.dielectric strength mainly depend upon
voltage(p.d).As potential difference is increased
,electrostatic stress on insulator is increase and at
certain voltage insulation rapture.Dielectrc strength of
insulator used in high tension side is high compare to low
tension side.
 When low tension side of transformer is connected with high
voltage then there is chance of insulation failure.Because
dielectrc strength of low tension side is small as compare
to high tension side.
 Theoretically it is possible.

in previous answer I mistyped that dielectric strength is
depend on pd sorry for that,actually rapturing of insulator
is depend on Pd.insulation used in low tension side is small
dielectric stength and this insulation will break down when
we will used high pd across low tension side
 but in theory point of view we can used