# Transformer equivalent circuit open and closed circuit test

• xdeimos
In summary, the open and closed circuit tests on transformers are important tests that measure voltage ratio, phase displacement, short-circuit impedance, and load loss. These tests help determine the efficiency and performance of the transformer.
xdeimos
I see the open and closed circuit test on the transformer section

I don't understand why we doing that(open and closed circuit test)

can anyone explain and give some example?

xdeimos said:
I see the open and closed circuit test on the transformer section

I don't understand why we doing that(open and closed circuit test)

can anyone explain and give some example?

Could you be more specific please? What kind of transformers? Where have you seen this? Can you post a link? Do you have any ideas yet for why it is done?

Transformer equivalent circuit open and closed circuit tests are some of required Power Transformer Tests [IEC 60076-1Standard]
1)Measurement of voltage ratio and check of phase displacement pen secondary winding test. Since primary EMF in this case is approximately equal to supply voltage and secondary EMF is secondary output voltage the ratio of primary to secondary voltage
it is EMF ratio then directly proportional with number of turns of the windings.
2) Measurement of short-circuit impedance and load loss :short-circuited secondary winding. The primary voltage will rise until the primary current shall not be less than 50 % of rated. The transformer short-circuit impedance will be then Voltage/Current. The resistance has to be
measured separately. As the supply voltage is reduced the no-load losses-magnetic losses-will be negligible. So the active power
measured in short-circuit test will be proportional will the load-loss.

## 1. What is the purpose of the transformer equivalent circuit open and closed circuit test?

The open and closed circuit tests are used to determine the equivalent circuit parameters of a transformer, which are necessary for its accurate modeling and analysis. These tests help in understanding the performance and efficiency of the transformer and can also be used to detect any faults or defects.

## 2. How is the open circuit test performed on a transformer?

In the open circuit test, the primary winding of the transformer is left open while a voltage is applied to the secondary winding. This results in a very small current flowing through the primary side, and the voltage across the secondary side is measured. This test is used to determine the core losses and leakage reactance of the transformer.

## 3. What is the purpose of the closed circuit test on a transformer?

The closed circuit test involves applying a voltage to the primary winding of the transformer while the secondary winding is short-circuited. This test helps in determining the copper losses and equivalent resistance of the transformer. It also provides information about the voltage regulation and efficiency of the transformer under loaded conditions.

## 4. How are the equivalent circuit parameters calculated from the open and closed circuit test results?

The equivalent circuit parameters, such as core losses, leakage reactance, and equivalent resistance, can be calculated using the results of the open and closed circuit tests. These values are then used to construct an equivalent circuit model of the transformer, which can be used for further analysis and calculations.

## 5. Are the open and closed circuit tests performed on all transformers?

Yes, the open and closed circuit tests are essential for all types of transformers, including distribution, power, and instrument transformers. These tests are crucial in determining the performance and efficiency of the transformer and are also used for quality control purposes during the manufacturing process.

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