Connecting Transformers with Two Secondary Windings: Series and Parallel Configurations

When working with transformers that have two secondary windings, the process of connecting them can vary significantly based on the required output voltage and the specific application. In this article, we will explore the methodology of connecting two secondary windings rated at 12V 2.5A each in both series and parallel configurations. We will also delve into the different methods of connecting these windings, including floating outputs and center-tapped configurations, with a focus on voltage regulation and power output.

Connecting Secondary Windings in Series

One way to connect the two secondary windings is to place them in series. In a series connection, the secondary terminal voltage will be the sum of the individual winding voltages. In your case, with each secondary winding rated at 12V, the total voltage across the series connection will be:

12V (first winding) 12V (second winding) 24V

This configuration is often used to achieve a higher overall voltage output from the transformer. However, it’s important to ensure that the current limit of both windings is taken into account, as the current through both windings will be the same.

Other Connection Methods

Depending on the specific requirements of your application, there are different ways to connect the two secondary windings. Here, we will discuss two main methods: connecting them as separate floating outputs and connecting them as a center-tapped output.

Separate Floating Outputs

For applications where you need two independent output voltages, a separate floating output configuration can be used. In this setup, the two windings are connected individually, and each provides its own independent voltage. For instance, if you need an output of 12V and another of -5V, you can connect the windings in such a way that they provide these independent outputs.

Center-Tapped Configuration

In a center-tapped configuration, the windings are connected such that they share a common return lead, usually the center tap. This configuration is useful when you need symmetric outputs with opposing polarities. For example, if you require a symmetric pair of outputs like -12VDC and 12VDC at 12 watts each, you can connect the windings to a ground-referenced center tap. Each output is referenced to the common return, ensuring that the voltages are symmetric but with opposite polarities.

Asymmetrical Center-Tapped Output

For asymmetrical outputs, where the power requirements differ, a center-tapped configuration can still be employed, but with additional considerations. Consider an example where one output is 5VDC at 5ADC (25W) and the other is 12VDC at 1.0ADC (12W), with the higher power output regulated. In this case, the 12VDC output might be connected to the 5VDC output as an autotransformer, and both share a common return line. This setup allows the 12VDC output to be at least partially regulated by the control loop that regulates the 5VDC output.

Conclusion

The method of connecting two secondary windings in a transformer depends on the application requirements. Whether you need independent floating outputs, symmetric outputs with a center tap, or asymmetrical outputs with regulated voltage, understanding the nuances of each connection method is crucial. Depending on the application, choosing the right configuration can significantly impact the functionality and efficiency of the transformer.

Key Takeaways

Series connection of secondary windings increases the output voltage by the sum of the individual windings. Floating outputs provide two independent voltage sources. Center-tapped output supplies symmetric but oppositely polarized voltages. Asymmetrical center-tapped configuration allows for different power requirements and regulated outputs.

Frequently Asked Questions

Q: How do you connect two transformers with different voltage outputs?
A: Connect them in a way that suits the output voltage requirements. For different voltage outputs, floating configurations may be used. For symmetrical outputs, a center-tapped configuration is appropriate. Q: What is the benefit of using a center-tapped transformer?
A: It allows for symmetric outputs with opposite polarities, which is useful in applications requiring balanced power supplies. Q: Can a transformer be used for asymmetrical power requirements?
A: Yes, by connecting the higher power output to the lower power output as an autotransformer, you can achieve asymmetrical voltage regulation.

Whether you are working on a project that requires a specific transformer configuration or just curious about the technical details, understanding these connection methods can help you achieve the desired output and ensure efficient and reliable operation of your circuit.