Final answer:
An open delta is a three-phase, four-wire power system using two transformers and is also known as a V-connection. It supplies reduced capacity three-phase and single-phase power, often used for light loads or when a third transformer is not cost-effective.
Step-by-step explanation:
A open delta is a variation of a three-phase, four-wire system that only utilizes two transformers. This system, also known as a V-connection or open delta connection, can supply three-phase power when one of the transformers in a delta-secondary is removed, leaving only two transformers in the circuit.
The open delta connection can provide power for balanced or unbalanced loads but with a reduced capacity compared to a conventional three-transformer delta system.
While the total power capacity is reduced to about 57.7% of a full three-transformer delta setup, the open delta retains the ability to supply both three-phase and single-phase loads. It is often used when three-phase power is needed but the load is light or the cost of a third transformer is not justified.