What winding configuration is used to step down from 480 VAC to 120 VAC?

The configuration used to step down from 480 VAC to 120 VAC is the transformer, which employs a specific winding configuration to achieve voltage transformation. In this context, transformers operate based on the number of turns in the primary and secondary windings.

For a transformer to reduce voltage, it must have a greater number of turns in the primary winding compared to the secondary winding. This step-down function can be designed in various ways, but it fundamentally revolves around technical principles of electromagnetic induction. Through this process, voltage is reduced (or stepped down) while current is increased, adhering to the principle of conservation of power (minus losses).

The terms "series" and "parallel" refer to types of circuit configurations generally associated with resistive components, not transformers. A series configuration increases voltage by summing voltages across components, whereas a parallel configuration maintains the same voltage across all components while increasing available current. Neither of these configurations would apply directly to stepping down voltage effectively from 480 VAC to 120 VAC.

Choosing a transformer as the solution indicates an understanding of how electrical voltage can be altered using inductive methods, making it the proper characterization for this application.