OPEN DELTA CONNECTION FOR LIGHT AND POWER BASIC AND TUTORIALS

Standard Connection
When the secondary circuits are to supply both light and power, the open-delta bank takes this form. In addition to the applications listed above for the open-delta bank for power, this type of bank is used where there is a large single-phase load and only a small three-phase load.

In this case, the two transformers would be of of different kva sizes, the one across which the lighting load is connected being the larger. This is also the connection that should be used when protected transformers are employed in a three-phase bank supplying both light and power.


Simplified Connection
This is similar to the connection above but gives a nonstandard 180° angular displacement. Otherwise the information given above is applicable to this connection.