Open And Short Circuit Test Of Transformer Pdf

open and short circuit test of transformer pdf

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We conduct open circuit and short circuit test on single phase transformer to determine the efficiency and regulation of a transformer on any load condition and at any power factor. This method of finding the parameters of a transformer is called as an indirect loading method. Open circuit test and short circuit test on the transformer are very economical and convenient because they are performed without actually loading of the transformer.

To determine the circuit constant, efficiency and regulation of a transformer, without actually loading the transformer, we perform Open-Circuit and Short-Circuit tests.

Open Circuit and Short Circuit Test on Transformer

To determine the circuit constant, efficiency and regulation of a transformer, without actually loading the transformer, we perform Open-Circuit and Short-Circuit tests. These tests give more accurate result than compared with the fully loaded transformer.

And the power consumption in these tests is minimal as compared with the transformer's output on full load. A voltmeter V, an ammeter A, and a wattmeter W are connected in the low voltage lv side of transformer.

The voltmeter v gives the rated voltage V 1 of the primary. A very small current I 0 , called the no-load current, flows in the primary side because the secondary side is open circuited.

The ammeter A, therefore, reads the no-load current I0. The power loss in the transformer occurs due to core loss and a very small I 2 R loss in the primary. Since the no-load current I 0 is very small, the I 2 R loss in the primary winding can be neglected. The instrument readings obtained in open circuit test are as follows:. In the short circuit test, usually, the low voltage side is short-circuited by a thick conductor.

As we can see that in the figure an ammeter, a voltmeter, and a wattmeter are connected on the high-voltage side. The reason for short-circuiting the low voltage side is as follows:.

The high voltage winding is supplied at the reduced voltage from a variable voltage supply. This supply voltage is gradually increased until full-load primary current flows. When the rated full load current flows in the primary winding, then it will also flow in the secondary winding by the transformer action.

When short circuit test is performed only on one side the equivalent circuit constants referred to another side can also be calculated as follows:. JavaTpoint offers too many high quality services. Mail us on hr javatpoint. Please mail your requirement at hr javatpoint. Duration: 1 week to 2 week. Electrical Machines.

Generators Speed Control of D. Motors Starting of D. Motors Types of D. Electrical Machines Interview. Next Topic Three-Phase Transformer. Manual T. Verbal A. Angular 7. Compiler D. Software E. Web Tech. Cyber Sec. Control S. Data Mining. Javatpoint Services JavaTpoint offers too many high quality services. Open Circuit Test The circuit diagram of the open circuit test for the transformer is shown below: Fig: Open Circuit Test on a Transformer A voltmeter V, an ammeter A, and a wattmeter W are connected in the low voltage lv side of transformer.

Short Circuit Test Fig: Short Circuit Test on a Transformer 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.

And we can measure this current with the help of available laboratory ammeters. Greater accuracy in the reading of the voltmeter is possible when we use the hv side as the primary because the applied voltage is less than 5 percent of the rated voltage of the winding.

ECE 494 - Electrical Engineering Laboratory III

These two transformer tests are performed to find the parameters of equivalent circuit of transformer and losses of the transformer. Open circuit test and short circuit test on transformer are very economical and convenient because they are performed without actually loading of the transformer. Open circuit test or no load test on a transformer is performed to determine 'no load loss core loss ' and 'no load current I 0 '. The circuit diagram for open circuit test is shown in the figure below. Usually high voltage HV winding is kept open and the low voltage LV winding is connected to its normal supply. Now, applied voltage is slowly increased from zero to normal rated value of the LV side with the help of a variac. When the applied voltage reaches to the rated value of the LV winding, readings from all the three instruments are taken.

Open Circuit & Short Circuit Tests on Transformers

It is possible to predict the performance of a transformer at various loadings by knowing all the equivalent circuit parameters. Without actually loading the transformer, these two assessed tests give the test results which are used to determine the equivalent circuit parameters. By these parameters, we can easily predetermine the efficiency and regulation of the transformer at any power factor condition as well as at any load condition. This method of finding the parameters of a transformer is called as an indirect loading method. This article enumerates how to perform these tests, how determine the equivalent parameters from test data and significance HV or LV side in which the calculation to be performed.

The open-circuit test , or no-load test , is one of the methods used in electrical engineering to determine the no-load impedance in the excitation branch of a transformer. The no load is represented by the open circuit, which is represented on the right side of the figure as the "hole" or incomplete part of the circuit. The secondary of the transformer is left open-circuited. A wattmeter is connected to the primary. An ammeter is connected in series with the primary winding.

If it is used for converting power from a high voltage to a low voltage, it is called a step-down transformer. The conversion efficiency of a power transformer is extremely high and almost all of the input power is supplied as output power at the secondary winding. The transformer may be represented by the equivalent circuit shown in figure 3. The parameters may be referred to either the primary or the secondary side.

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. The open circuit and the short circuit test gives a very accurate result as compared to the full load test.

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ECE 494 - Electrical Engineering Laboratory III

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Toni R.

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These two transformer tests are performed to find the parameters of equivalent circuit of transformer and losses of the transformer. Open circuit test and short.

Tilly V.

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