Open Circuit of a 1 phase transformer |how would you perform| LEARN AS TOPPER

Q-  Draw the connection diagram for the open circuit and short circuit tests of a 1-φ transformer showing all the necessary instruments/meters. Describe how would you perform these tests?

SHORT CIRCUIT TEST OF A TRANSFORMER?

OPEN- CIRCUIT TEST

The purpose of the open-circuit test is to determine the no-load current and losses of the transformer because of which their no-load parameters are determined. This test is performed on the primary winding of the transformer. The wattmeter, ammeter and the voltage are connected to their primary winding. The nominal rated voltage is supplied to their primary winding with the help of the ac source.

The secondary winding of the transformer is kept open, and the voltmeter is connected to their terminal. This voltmeter measures the secondary induced voltage. As the secondary of the transformer is open, thus no-load current flows through the primary winding

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The value of no-load current is very small as compared to the full rated current. The copper loss occurs only on the primary winding of the transformer because the secondary winding is open. The reading of the wattmeter only represents the core and iron losses. The core loss of the transformer is the same for all types of loads.

     

OPEN CIRCUIT TEST | LEARN AS TOPPER

Let,

W₀ – wattmeter reading

V₁ – voltmeter reading

I₀ – ammeter reading

Then the iron loss of the transformer,  Pi = W0 

The no-load power factor is

Working component I_w is

Putting the value of W0 from the equation (1) in equation (2) you will get the value of the working component as

Magnetizing component is

No-load parameters are given below:
  Equivalent exciting resistance is

• Equivalent exciting reactance is 

SHORT CIRCUIT TEST

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