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Transformer - Short Circuit Test

This document describes a procedure for conducting a short-circuit test on a single-phase transformer to determine its full load copper loss, equivalent reactance, and equivalent resistance referred to the secondary side. The test involves short-circuiting the secondary windings, applying a low voltage to the primary, and measuring the current, voltage, and power. These measurements are used to calculate the equivalent circuit parameters according to formulas provided in the theory section. A pre-lab exercise is also given to practice calculating these parameters from sample test data.

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Elisha Nissi
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98 views2 pages

Transformer - Short Circuit Test

This document describes a procedure for conducting a short-circuit test on a single-phase transformer to determine its full load copper loss, equivalent reactance, and equivalent resistance referred to the secondary side. The test involves short-circuiting the secondary windings, applying a low voltage to the primary, and measuring the current, voltage, and power. These measurements are used to calculate the equivalent circuit parameters according to formulas provided in the theory section. A pre-lab exercise is also given to practice calculating these parameters from sample test data.

Uploaded by

Elisha Nissi
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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SCHOOL OF ELECTRICAL AND ELECTRONICS ENGINNERING

SHORT - CIRCUIT TEST ON A SINGLE-PHASE TRANSFORMER

OBJECTIVE
To carry out Short - circuit test on a single-phase transformer

THEORY B
The purpose of this test is to determine full load copper loss, equivalent reactance and
equivalent resistance as referred to the metering side. Since applied voltage is very low
(5-10% of rated voltage), flux linking with the core is very small and therefore iron losses
are so small that these can be neglected, therefore the power input (the wattmeter
reading) gives total primary and secondary copper loss at rated load.
Full load copper loss is given by PSC = ISC2Req
Equivalent resistance referred to the metering side R01 = PSC/ ISC2
Equivalent impedance referred to the metering side Z01 = VSC/ISC
Equivalent reactance referred to the metering side X01 = √ Z012- R012

PRE-LAB EXERCISE
The primary of a single phase transformer is rated at 10A and 1000V. On short circuit
test, the readings are I1= 10A, V1 =126V and PSC = 400W. Find parameters of equivalent
circuit as referred to the secondary side.

INSTRUMENTS AND EQUIPMENT


1. Power supply: variable line 0 to 500 Va.c 4A
2. Moving-iron ammeter 2-4A
3. Moving-iron voltmeter 25-50V
4. Electrodynamic wattmeter 2-4A/250-500V
5. Machine mod. M-13/EV (rating: 240/415V)

Machines lab Page 1


CIRCUIT DIAGRAM

Figure 1

PROCEDURE

Note - for higher accuracy, the short circuit test must be as short as possible

1. Connect the circuit as shown in figure 1with the primary of the transformer
connected to the terminals of the a.c. variable line (phase and neutral)
2. Short-circuit both the secondary windings by a thick wire or strip or through an
ammeter
3. Switch on the power supply and increase the voltage gradually until a current
value equal to 3.5A rated value (or even 10% higher) can be read on the ammeter,
at the same time, read the voltage and the power
4. Tabulate the results as shown in the table below
5. From the test results and the transformer rating mentioned above, find parameters
of equivalent circuit as referred to the secondary side
6. Write report for the exercise

PSC (watts) VSC (V) ISC (A)

Machines lab Page 2

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