A single-phase 10-kVA 480/120-V transformer is to be used as an autotransformer tying a 600-V distribution...

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A single-phase 10-kVA 480/120-V transformer is to be used as an autotransformer tying a 600-V distribution line to a 480-V load. When it is tested as a conventional transformer, the following values are measured on the primary (480-V) side of the transformer: Open-circuit test Voc=480 V Loc=0.41 A Voc= 38 W Short-circuit test Vsc = 10.0 V Isc = 10.6 A Psc = 26 W (a) Find the per-unit equivalent circuit of this transformer when it is connected in the conventional manner. What is the efficiency of the transformer at rated conditions and unity power factor? What is the voltage regulation at those conditions? (b) Sketch the transformer connections when it is used as a 600/480-V step-down autotransformer. (c) What is the kilovoltampere rating of this transformer when it is used in the autotransformer connection? (d) Answer the questions in (a) for the autotransformer connection. A single-phase 10-kVA 480/120-V transformer is to be used as an autotransformer tying a 600-V distribution line to a 480-V load. When it is tested as a conventional transformer, the following values are measured on the primary (480-V) side of the transformer: Open-circuit test Voc=480 V Loc=0.41 A Voc= 38 W Short-circuit test Vsc = 10.0 V Isc = 10.6 A Psc = 26 W (a) Find the per-unit equivalent circuit of this transformer when it is connected in the conventional manner. What is the efficiency of the transformer at rated conditions and unity power factor? What is the voltage regulation at those conditions? (b) Sketch the transformer connections when it is used as a 600/480-V step-down autotransformer. (c) What is the kilovoltampere rating of this transformer when it is used in the autotransformer connection? (d) Answer the questions in (a) for the autotransformer connection.

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