When connecting a secondary winding to match a 240-volt load, what configuration is needed?

To connect a secondary winding that matches a 240-volt load, a closed delta configuration is the appropriate choice. This configuration consists of three windings that are connected in a triangle shape, which allows for both voltage and current to be fully utilized across the load.

In a closed delta setup, the voltage between any two phases is determined by the line-to-line voltage, which is typically higher than the phase voltage. For a 240-volt load, a closed delta connection can efficiently supply this voltage because it allows for the generation of such line-to-line voltages necessary to meet the demands of the load. This configuration also enables the system to handle higher power ratings and provides redundancy; if one transformer in the setup were to fail, the remaining two can still continue supplying power to the load.

Other configurations, such as open delta or star, do not provide the necessary voltage scaling or redundancy needed for a robust and efficient connection. An open delta would only provide two-thirds of the potential power required, and a star configuration would provide a lower line-to-line voltage, making it unsuitable for a 240-volt requirement. Hence, the closed delta configuration is the most effective and reliable choice to match a 240-volt load.