Open Delta ?

[winnie]

Three-Phase, "open delta" transformer banks are only open delta on the secondary. The primary is open wye. Each of the two primaries are connected line-to-neutral.

As @LarryFine noted, this is the most common or universal "open delta" arrangement.

But there is no reason they couldn't be built with two bushing transformers connected line-line as two legs of a delta primary.

You can have 'open wye: open delta' (most common) or 'open delta: open delta' (rare, possibly never, but in theory perfectly possible).

-Jon

 

[gar]

230410-1054 EDT

An open delta primary with no third secondary transformer with the secondary wired delta works the same as a full delta.

An open delta primary with secondaries connected in a wye does not provide three equal voltages spaced 120 degrees apart.

On the combinations that don't directly produce three balanced outputs you can with additional secondary windings produce three phase balanced outputs.

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