When a buck-boost transformer is used to buck the input voltage, how are the primary and secondary voltages related?

In the case of a buck-boost transformer being used to lower the input voltage, the relationship between the primary and secondary voltages is subtractive. The primary voltage, which is the input voltage supplied to the transformer, will have a certain value, and the secondary voltage is derived from this primary voltage with a reduction or "buck" effect.

When the transformer is configured to buck, the secondary winding is connected in such a way that it introduces a voltage drop relative to the primary. Therefore, the total voltage measured across the entire transformer can be expressed as the primary voltage minus the secondary voltage. This establishes a subtractive relationship where the secondary voltage is effectively reducing the total voltage being output, ensuring that the output voltage is less than the input.

This configuration allows for adjustments in voltage that are beneficial in applications where specific lower voltage levels are required to power equipment safely and effectively. Understanding this relationship is crucial for electrical contractors when implementing solutions for voltage regulation and control.