Download Short circuit test

Objective: objective of this experiment is to study the equivalent circuit of
transformer. And determine the transformer parameter by short circuit and open
circuit test. The purpose of this two types of test is to determine the magnetizing
reactance, equivalent core loss resistance and equivalent impedance of transformer.
Circuit Diagram:
Fig:01 Short circuit test of transformer.
Fig: open circuit test of transformer.
Data:
For open circuit test:
𝑉𝑂𝐶
56V
𝐼𝑜
.05A
𝑃𝑜𝑐
3W
𝐼𝑓𝑒
.053A
𝑅𝑓𝑒
𝑋𝑀
1054.34Ω 3200Ω
𝐼𝑚
0.017A
For short circuit test:
𝑉𝑇
𝐼𝑆𝐶
.01A
18V
𝑃𝑆𝐶
1.5W
𝑍𝑒𝑞,1−2
2000Ω
𝑅𝑒𝑞,12
15000Ω
𝑋𝑒𝑞1−2
J14866
Ans the post lab report question no 01
Here , equivalent parameter for High side
𝑉𝑠𝑐 =18V,
𝐼𝑆𝐶 =.01A
𝑃𝑆𝐶 =1.5w
Now
𝑍𝑒𝑞𝐻𝑆 =
𝑉𝑂𝐶
𝑅𝑒𝑞𝐻𝑆 =
=1800,
𝐼𝑆𝐶
𝑃𝑆𝐶
𝐼𝑠𝑐 2
=15000
𝑋𝑒𝑞𝐻𝑆 =√(𝑅𝑒𝑞𝐻𝑆 2 +𝑍𝑒𝑞𝐻𝑆 2 )=14866
𝑍𝑒𝑞𝐻𝑆
1800Ω
𝑅𝑒𝑞𝐻𝑆
15000Ω
𝑋𝑒𝑞𝐻𝑆
14866Ω
Here, equivalent parameter for Low side
𝑉𝑂𝐶 =56V
𝐼𝑜 =0.05A
𝑃𝑜𝑐 =3W
𝐼𝑓𝑒 =
𝑃𝑜𝑐
𝑉𝑂𝐶
=0.05357A
𝑉𝑂𝐶
𝑅𝑓𝑒 =
𝐼𝑓𝑒
=1045.33
𝐼𝑀 =√(𝐼𝑜 2 +𝐼𝑓𝑒 2 )=0.0175
𝑋𝑚,𝐿𝑆 =
𝑉𝑂𝐶
𝐼𝑀
=3200
𝑅𝑓𝑒,𝐿𝑆
1045.33Ω
𝑋𝑚,𝐿𝑆
3200Ω
Ans the question no 02
Open circuit test: the no load is connected to the secondary, the copper loss in the
secondary are Zero. Copper loss in the primary are negligible. Thus the wattmeter
reading is core loss.
Short circuit test: In short circuit test, voltage is low but the current is standard.
So the only losses are due to resistance of conductor. In short circuit the secondary
causes the flux density to be reduce to a very low value, making the core loss
insignificant. Thus the wattmeter reading in short circuit test is copper loss.
Ans the question no 03
𝑬′𝑳𝒔
𝑰𝑳𝑺 𝑿𝒆𝒒𝑳𝒔
𝑽𝑳𝑺
ᶿ
𝐼𝐿𝑆 𝑅𝑒𝑞𝐿𝑆
𝑰𝑳𝑺
Fig: 01 inductive load
ILS
ILS XeqLs
𝐼𝐿𝑆 𝑅𝑒𝑞𝐿𝑆
VLS
Fig: 02 capacitive load
ILS XeqLs
ᶿ
VLS
Fig:03 resistive load
𝐼𝐿𝑆 𝑅𝑒𝑞𝐿𝑆
Ans the question no o4
Why low tension side is short circuit:
In short circuit test the test is performed at rated current. As the rated current on
high voltage side is much more then less than low voltage side. So this the rated
high voltage side current is easily achieved.
Another we cannot perform short circuit on high voltage side, because the high
voltage side essentially falls to zero and since KVA power=constant, so high
voltage side current will be very high and can burn the winding.
Also short circuit test can perform other side when rating is very small.
Ans the question no 05
Modification in short circuit test:
The test is conducted on the high-voltage (HV) side of the transformer where the
low-voltage (LV) side or the secondary is short circuited. The supply voltage
required to circulate rated current through the transformer is usually very small and
is of the order of a few percent of the nominal voltage and this 5% voltage is
applied across primary. The core losses are very small because applied voltage is
only a few percentage of the nominal voltage and hence can be neglected. Thus the
wattmeter reading measures only the full load copper loss
Disscussion: In short circuit test the equivalent inpedence gives negative value
Conclusion: after performing this experiment we know how to perform
transformer test for open and short circuit test. Also know the transformer
parameter can be obtain by short circuit and open circuit test. Know why short
circuit test perform on high voltage side.
DEPARTMENT OF ELECTRICAL AND ELECTRONIC
ENGINEERING
LAB REPORT
Course Code
: EEE 301
Experiment No
: 02
Experiment Name : Determination of equivalent circuit parameter of a
transformer.
Performed date: 28/02/2015
Student Name: MD. Samiul Islam
Submitted date: 04/03/2015
Student ID : 2013-1-80-014
Group : 04
Group members ID:
2013-1-80-011
2013-1-80-013
2012-3-80-040
2013-1-80-016