3phase 120VAC open delta VT connections

[1948rspower]

I received a submittal drawing for a SEL 751A relay, and it indicates a customer 3 phase 120VAC open delta VT connection. Can you assist in this transformer connection? I know of 3 phase, 120/208VAC, wye connection but never seen a 3 phase 120VAC open delta connection. That would have a high leg typically if a three phase delta connection.

 

[GoldDigger]

Well, it could be a high leg delta, since with a relatively light three phase load POCO will often use an open delta, saving a transformer. As far as monitoring and metering go, it should not be any different from a closed delta. It does have a high leg, if it really is a 120/240 three phase four wire. The only difference is that the high leg is fed by one transformer, not two.

 

[jim dungar]

For metering purposes, 120V open delta connections are very common. Normally they are connected as corner grounded systems.
There is almost never any multi-voltages available.