Why short circuit test is performed on high voltage side of a transformer
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24 ANSWERS

Jim Phipps, Power systems engineer (30 yrs in the T&D industry)
Answered Jul 7, 2017 · Author has 902answers and 699.8k answer views
Originally Answered: Why is a short circuit test in a transformer done on the high voltage side only?
The reason that a power transformer short circuit test is performed on the HV side is mostly due to the limitations of the power supply used to perform the test. Let us review:
The purpose for performing a short circuit test in the first place is to measure the positive-sequence impedance of the transformer ZZ. It is expressed as a percentage of the rated voltage applied to the transformer that results in rated current when the output is short circuited. It is measured at the factory using a balanced short circuit test as shown in the following single-phase equivalent circuit:

Why is a short-circuit test, in the case of transformers, done with the high-voltage side only?
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24 ANSWERS

Jim Phipps, Power systems engineer (30 yrs in the T&D industry)
Answered Jul 7, 2017 · Author has 902answers and 699.8k answer views
Originally Answered: Why is a short circuit test in a transformer done on the high voltage side only?
The reason that a power transformer short circuit test is performed on the HV side is mostly due to the limitations of the power supply used to perform the test. Let us review:
The purpose for performing a short circuit test in the first place is to measure the positive-sequence impedance of the transformer ZZ. It is expressed as a percentage of the rated voltage applied to the transformer that results in rated current when the output is short circuited. It is measured at the factory using a balanced short circuit test as shown in the following single-phase equivalent circuit:

The low-voltage (LV) winding is shorted. A balanced three-phase, alternating current (AC), variable voltage source is used to excite the high-voltage (HV) winding. The voltage source is increased from zero until rated current is measured in the HV winding using an ammeter (A). Once this operating point is reached, the HV voltage is measured with a voltmeter (V). The impedance-voltage is then expressed as a percent of the rated voltage of the transformer Z=V/Vrated×100Z=V/Vrated×100. Since the full-load current of the HV winding is typically only in the 100’s of amps range, the power supply capability can be reduced (e.g., a less expensive power supply).
If the test was performed on the LV winding, the power supply would need to have the capability of producing 1000’s of amps since the full load current of the LV winding is greater by the voltage ratio HV/LVHV/LV of the transformer.
Thus, all short circuit tests are performed on the HV side because the power supply capabilities (and cost) are reduced.
Answer:
Explanation:
short circuit test is performed on high voltage side of a transformer:
The SC test is performed on the HV side, together with the placement of the measurement equipment and shorting of the LV side. The key justification for doing the SC test on the HV side is that it will result in a lower rated current than on the LV side.
The results might not be very accurate because such a wide range of instruments and an Auto Transformer that can handle 150 A may not be easily accessible. These are the reasons why the LV side is subjected to an open circuit test, and the HV side to a short circuit test.
The transformer's low-voltage (LV) side, also known as the secondary, is short-circuited, thus the test is done on the high-voltage (HV) side of the transformer.
Our goal in a short circuit test is to determine the equivalent circuit's series branch characteristics and cu losses of T/F.
Applying 5–6% of the normal voltage will yield an easily accomplished short circuit test of the T/F at its rated current. Normally, we short the LV windings and do the test from the LV side.
Since the rated high voltage side current is substantially lower than the rated lv side current (VI = constant), this may be done with ease (compared to lv side).
Additionally, we are unable to short-circuit the high-voltage side because doing so would result in a rapid drop in voltage, a very large high voltage current (relative to the low rated current on the high-voltage side), and eventual burnout of the high-voltage side.
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