Unbalanced three phase delta system

Do you mean a healthy unbalanced Delta system or an open circuit Delta system?

Both have been answered at length in this forum - search it

In this case, you have to analyse the system by using symetrical components.

As per your description, you will only load one or two phases of the system.

Therefore, the system will behave as a non balanced system and therefore the only way to study it will be through symetrical components.

Try it.

An Open Delta system has always been viewed as an economical way of feeding a three phase load. It is ok as long as the system is not fully or overloaded.

However if the connected loads include sensitive electronic equipment such as motors, drives computers etc then you will experience significant system instability.

An open delta system is not as we say a very stiff system. But it can save the day as temporary supply or provide an economic alternative for a single non sensitive load.

As far as the supply Alternator is concerned little impact. The Alternator will see a balanced load. The loading capacity of the 2 single phase transformers will be 86.6% of the equivalent 3 single phase transformers. Refer to the J & P Transformer Book, where the open Delta or "V" connection is is discussed in some depth.

Greg Lynch