Question

Please answer the problem below for all parts . Please show all work and write clearly. Thanks.

(a) (0) What is the difference between an autotransformer and a conventional transformer? 2. (ii) Why are high-impedance transformer used in electric toys? (b) Three single-phase transformers each rated at 150 kVA, 7200 V/600 V, 60 Hz, are connected in wye-delta on a 12470 V, 3-phase line. If the load is 450 kVA, calculate the followings: (i) The current flowing in the incoming and outgoing transmission lines. (ii) The current flowing in the primary and secondary windings. (ii) Draw the schematic diagram of the transformer and show the current flowing through each of the windings and the voltage across each of the windings.

Answer 1

i)There are several differences between the autotransformerand the conventional transfomer. One of the major differences between themis that the autotransfomer has only one winding whereas the has two separate windings

Basis For Differences Autortransformer Conventional transformer Definition A transformer, having only one winding a part of which acts as a pri a ry and the other as a secondary It is a static machine which transfers electrical energy from one end to another without changing frequency Number of Auto-transformer has only one winding wound on a laminated core It has two separate winding, i.e., primary and secondary winding. Windings EIE Symbol Circuit Globe Circuit Globe Insulation The primary and secondary winding are not electrically insulated. The primary and secondary winding are electrically insulated from each other. Induction Size Power Self Induction Mutual Induction Large Through transformation Small Partly by transformation and partly by direct electrical connection. Transfer Voltage Better Good

ii) Transformers are a key component in tuming electricity into movement,,If a toy received full voltage, it would explode or catch fire, potentially resulting in injuries and accidents. This is where transfomers come in, taking the high-voltage alternating current (AC) emanating from the power outlet andtransforming it or stepping it down to the toy's specific voltage requirement. So that tom step down the high voltage the high impedance transformers are required.

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