Electrical

Types of Autotransfomer Q. What are the two different types of Autotransformer?       Type No.1 : Step down Autotransformer       Type No.2 : Step up Autotransformer Generally stepdown type is universally used to get a variable voltage from a supply (primary) Relations of Primary / Secondary Voltage, Currents and Transformation Rations … Read more

Advantages Disadvantages and Application of Autotransformer Q. What are advantages of an autotransformer Advantages of Autotransformer As only one winding serves as primary and also secondary, there is a saving in winding material i.e copper saving. Size is small. Cost is lesser than two winding transformer. very easy way of changing voltage. Desired voltage can … Read more

Construction of Autotransformer  AutoTransformer Main parts of Auto transformer    1. Core    2. Winding    3. Wheel (Handle)    4. Brush    5. Outer    6. Terminal box. Core : Core is made of best quality silicon steel stampings assembled to form circular (cylindrical shape). Winding : Super enamelled copper wire of high grade copper … Read more

Mechanical Forces on Transformer To overcome the problems of mechanical forces, circular coils should be used for the windings, as they can with stand the radial forces (in circular coils radial forces are cancelled by each other). Wherever it is not possible to use the circular coils, (e.g. shell type transformer) they should be braced … Read more

Comparison of Power Transformer and Distribution Transformer Q. Compare power transformer with distribution transformer Sr. No. Power Transformer Distribution Transformer 1 The rating of power transformer is very high (in MV As). The rating is in KVA and small. 2 This are used at generating stations is very high voltage transmission line and at receiving … Read more

Lightening impulse test : (This is a type test) Q. Describe the impulse voltage withstand test on transformers. In practice the transformer is subjected to lightening strokes and switching surges. In such case ordinary high voltage tests are not useful. The test voltage wave is generated by a special type of generator known as impulse … Read more

Induced over-voltage withstand test This test is routine test i.e. it is carried on all the transformers. Before commissioning the transformer it is necessary to know that the insulation resistance of a transformer is greater than a specified value, to avoid excessive leakage currents. Megger test for insulation are carried out between windings, between winding … Read more