What do you need on the secondary side of a transformer to create a "z-bank"?

To create a "z-bank" on the secondary side of a transformer, you need four bushings. A z-bank configuration typically refers to a specific arrangement used in three-phase applications to effectively distribute electrical load and manage phase connections. With four bushings, you can create the necessary connections to configure the phases in a way that allows for a balanced load and improved electrical performance. This setup supports the functionality required for proper phase rotation and ensuring that the transformer operates efficiently and reliably.

Having fewer bushings would not provide the necessary connections for a complete and effective z-bank arrangement, while having more than four could lead to redundancy or complications in the circuit design. Thus, four bushings are optimal for creating a z-bank in transformer applications.