1.
The nominal short-circuit voltage VSCN of a transformer means the
a)
Voltage across the primary terminals
when the secondary terminals are short circuited
b)
Voltage appearing across the secondary
terminals when they are short circuited
c)
Primary voltage when secondary terminals
are short circuited and the reated current fllows through the primary winding
d)
None of the above
2.
During short circuit test the core
losses are negligible this is because
a)
The voltage applied across high voltage
side is a fraction of its rated voltage & so is the mutual flux
b)
The current on the LV side is very small
c)
The power factor is high
d)
Iron becomes full satuarated
3.
While performing the open circuit &
short circuit tests on a transformer to determine parameters the status of LV & HV windings will be such that
a)
In OC ,LV is open & in SC HV is
shorted
b)
In OC , HV is open & in SC LV is
shorted
c)
In OC, LV is open & in SC LV is
shorted
d)
In OC, HV is open & in SC HV is
shorted
4.
For a transformer to be tested at full
load conditions but consuming only losses from mains , we do
a)
Load test
b)
open circuit & short circuit test
c)
back-to-back test
d)
none of the above
5.
The efficiency of two identical
transformers under load conditions can be determined by
a)
Back to back test
b)
Open circuit test
c)
Short circuit test
d)
Any of the above
6.
The efficiency of a power transformer
can be determined indirectly by
a)
Open circuit test alone
b)
Short circuit test alone
c)
Open circuit & short circuit tests
d)
Back-to-back test
Ans: c
7.
Transformer will operate at maximum
efficiency when
a)
Hysteresis loss=eddy current loss
b)
Eddy current loss =copper loss
c)
Copper loss=iron loss
d)
Hysteresis loss = copper loss
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