What advantage does the open delta secondary have over the closed delta secondary when supplying a 120/240 single-phase load?

The open delta secondary configuration has a key advantage when supplying a 120/240 single-phase load, particularly in its ability to effectively provide power from less transformer capacity than a closed delta. In an open delta system, only two transformers are used instead of three, which allows it to operate with a reduced number of units while still delivering sufficient power for loads.

While this configuration may not deliver the total power available from a closed delta, it can supply adequate voltage and current for certain applications. Importantly, this system allows for efficient delivery of power under specific conditions, especially in scenarios where full power capacity is not required, minimizing potential losses.

The open delta configuration also enables power delivery despite the absence of one transformer's output, which can be particularly beneficial during maintenance or transformer failure. This adaptability, along with the ability to still provide significant loads with less transformer infrastructure, supports the idea that the system can operate effectively and efficiently, giving the appearance of providing power without significant loss.