Contents
What is OC and SC test in transformer?
The open circuit and short circuit test are performed for determining the parameter of the transformer like their efficiency, voltage regulation, circuit constant etc. These tests are performed without the actual loading and because of this reason the very less power is required for the test.
Why does SC test require reduced voltage?
In the short circuit test, usually, the low voltage side is short-circuited by a thick conductor. The reason for short-circuiting the low voltage side is as follows: The rated current on the high voltage (hv) side of a transformer is less than the low voltage (lv) side of the transformer.
What are the advantages of OC and SC test on a transformer?
These tests are very convenient as they provide the required information without actually loading the transformer. Further, the power required to carry out these tests is very small as compared with the full-load output of the transformer.
Why OC and SC test is performed on HV and LV side respectively?
Short circuit test in the transformer is conducted on the high voltage side and low voltage side is short-circuited. In HV winding, the rated current is less than LV winding. As rated current is less on HV side, it is convenient to conduct this test on HV side by short-circuiting the LV terminals.
Why is SC test carried by Energising side?
The SC test is conducted on HV side due to the two main reasons. Therefore, the rated current is easily achieved at HV side (due to the low current value) as compared to the LV side. On the other hand, if we short the HV terminals by connecting measuring instrument on LV side, voltage in the secondary is zero.
How do you know if a transformer is shorted?
A suspected short can be checked with an ohmmeter across the secondary winding with the source and load disconnected. If there is a short, the meter will read 0 Ω. Again the meter should be on a low scale.
Why LV winding is shorted during SC test in case of large transformers?
For an SC test, the low voltage side is shorted in order to measure the impedance of the transformer. The high voltage winding is connected to a variable voltage supply, and the supply is increased until the high voltage leg reads it’s maximum current.
Why iron losses are neglected in SC test?
Since the applied voltage Vsc is short circuitvoltage in the transformer and hence it is quite small compared to the rated voltage, so, we can neglect the core loss due to the small applied voltage.
Which is side of the transformer does the SC test on?
It should be noted that, before calculation of parameters, you must be aware in which side (primary or secondary) the test reading being recorded. Suppose if the transformer is step-up transformer, then we carry out the SC test on secondary side (HV side) while primary or low voltage side is shorted.
What kind of tests are done on a transformer?
Mainly two tests carried out on the electrical transformer that are open circuit and short circuit test of the transformer also known as SC and OC test.
How are O.C and s.c.tests on single phase transformer?
O.C. and S.C. Tests on Single Phase Transformer The efficiency and regulation of a transformer on any load condition and at any power factor condition can be predetermined by indirect loading method. In this method, the actual load is not used on transformer.
How are the circuit parameters of a transformer determined?
But the equivalent circuit parameters of a transformer are determined by conducting two tests on a transformer which are, 1. Open circuit test (O.C Test) 2. Short circuit test (S.C.Test)