Testing of power transformer – Measurement of impedance voltage and load loss

    Purpose of the measurement The measurement is carried out to determine the load-losses of the transformer and the impedance voltage at rated frequency and rated current.  The measurements are made separately for each winding pair (e.g., the pairs 1-2, 1-3 and 2-3 for a three-winding transformer), and furthermore on the principal and extreme tappings.   Apparatus and measuring circuit On Figure 1 above (Circuit for...

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2. No-Load Excitation Current

This current is measured in the winding used to excite the transformer with the other windings open-circuited. It is generally expressed in percent of the rated current of the winding. No-load excitation current is not sinusoidal and contains, as we have seen, odd harmonics (predominantly third harmonic current). The ammeter used to record the no-load excitation current is an RMS meter which reads the square root of the sum of the squares of the harmonic current...

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Transformer Routine Test – Measurement Of No-Load Loss And Current

Introduction to test The no-load losses are very much related to the operational performance of a transformer. As long as the transformer is operated, these losses occur. For this reason, no load losses are very important for operational economy. No-load losses are also used in the heating test. The no-load loss and current measurements of a transformer are made while one of the windings (usually the HV winding) is kept open and the other winding...

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