Electrical Machines
Subject and UNIT: Electrical Machines: Unit V: Autotransformer and Three Phase Transformer
Electrical Machines: Unit V: Autotransformer and Three Phase Transformer : Syllabus, Contents
Single Phase Transformer | Electrical Machines
Subject and UNIT: Electrical Machines: Unit IV: Single Phase Transformer
Electrical Machines: Unit IV: Single Phase Transformer : Two Marks Questions and Answers
Subject and UNIT: Electrical Machines: Unit IV: Single Phase Transformer
The various applications of single phase transformers are,
Single Phase Transformer
Subject and UNIT: Electrical Machines: Unit IV: Single Phase Transformer
• When the primary voltage V1 is switched on to the transformer, the core flux and the exciting current undergo a transient before achieving the steady state. They pass through a transient period. The effect of transients is severe when voltage wave passes through origin.
Single Phase Transformer
Subject and UNIT: Electrical Machines: Unit IV: Single Phase Transformer
• The voltage ratios of the two transformers are not equal. The parallel operation under this case is still possible. But as seen previously there would be a circulating current under no load condition.
Single Phase Transformer
Subject and UNIT: Electrical Machines: Unit IV: Single Phase Transformer
• Let us now consider the case of two transformers connected in parallel having equal voltage ratios. The two transformers are having no load secondary voltage same.
Subject and UNIT: Electrical Machines: Unit IV: Single Phase Transformer
• Now we will consider ideal case of two transformers having the same voltage ratio and their voltage triangles are equal in size and shape. The circuit shown in the Fig. 6.24.1 consists of two transformers in parallel.
Single Phase Transformer
Subject and UNIT: Electrical Machines: Unit IV: Single Phase Transformer
•The conditions that must be followed for satisfactory parallel operation of transformers are as follows:
Subject and UNIT: Electrical Machines: Unit IV: Single Phase Transformer
• The transformers are connected in parallel when the load on them is more than the rating of the individual transformers. Several smaller units are operated in parallel which share a common load. Thus it is avoided that the total load is supplied by single unit due to use of parallel operation. The parallel operation is advantageous in the sense that the spare parts can be used interchangeably and their storage is easy.
Single Phase Transformer
Subject and UNIT: Electrical Machines: Unit IV: Single Phase Transformer
• For a given volume and thickeness of laminations, these losses depend on the operating frequency, maximum flux density in the core and the voltage.
Single Phase Transformer
Subject and UNIT: Electrical Machines: Unit IV: Single Phase Transformer
• For a transformer, the efficiency is defined as the ratio of output power to input power. This is its power efficiency. But power efficiency is not the true measure of the performance of some special types of transformers such as distribution transformers.
Single Phase Transformer
Subject and UNIT: Electrical Machines: Unit IV: Single Phase Transformer
• The Sumpner's test is another method of determining efficiency, regulation and heating under load conditions. The O.C. and S.C. tests give us the equivalent circuit parameters but cannot give heating information under various load conditions.