Single-Phase Transformers - Assignment Example

In this report, single-phase transformers were studied for their current and voltage characteristics under various variations. A single-phase transformer consists of two windings, the primary windings, and the secondary windings. In normal circumstances, the primary winding is connected to the power input into the transformer while the secondary winding is connected to the load. Both the primary and secondary winding is electrically isolated with electromagnetic induction being the only channel of connection. There exists a relationship between the number of primary windings and secondary windings and the amount of current and voltage in the output of the transformer.

A better understanding of the dynamics and characteristics of the transformers depends on the nature of the learners’ exposure. Practical observation of the transformer in operation as well as the measurement of some of its parameters such as current and voltage is a key way of fostering understanding. Further analysis of the results by the use of visual representation techniques ensures a greater understanding.

The design methodology of this practical, therefore, takes into consideration the above-mentioned learning techniques. By the end of the session, the students should have a deeper understanding of the single-phase transformers.

As shown by the results in the table, the voltage in the primary circuit is higher than that in the secondary circuit. This means that the single-phase transformer under consideration is a step-down transformer. Since there single-phase transformer is under no loading, the current required to excite the system is minimal. Only a small amount of current is required to create a magnetic flux in the system (Wakileh, 2001).

The turn ratio for an unloaded transformer can be determined by finding the ratio of applied voltage and voltage in the secondary winding as shown in expression (i) above. Thus the average turn ratio for the transformer under consideration was found as follows.
- Average E PRI = 126.45 Volts,
- Average E SEC = 58.6693 Volts.

To avoid cases of damage to the windings, the voltage applied to the primary winding is kept low as shown in the table above.

As shown in the graph above, the exciting current increases in direct proportion to the applied voltage until when the core saturation point is reached. The direct proportionality in the graph is shown by the linear part of the graph. Therefore, it is true that the exciting current has a direct relationship with alternating magnetic flux (Burke, 1994). The core saturation is reached when the applied voltage exceeds the rated capacity of the primary circuit thus breaking down the linear relationship. Therefore, as the graph slowly flattens after core saturation, a smaller increase in the transformer voltage results in a larger increase in the exciting current.

The data collection and analysis process is one tool for ensuring that learners get a maximum understanding of the topic under study. The various data points measured and recorded as well as the interpretation of the data by use of graphs is the best way to ensure understanding of the subject under study.

The relationship between primary and secondary voltages in a transformer as well as that of turn ratio was determined by the study of single-phase transformers. The relationship between the exciting current and applied voltage was also determined by the use of a graphical representation. A deeper understanding of the reasons for this relationship was also determined and explained in the discussion section.

The effect of the application of voltage to the primary circuit and its resulting saturation is a phenomenon that was also studied. The effects of core saturation on the various parameters such as voltage ratio were also examined.