Flex
Senior Member
- Location
- poestenkill ny
Why would a delta to delta transformer have an X0 terminal on the secondary side?
Because it is actually a delta to wye transformer (which could be used to feed a delta wired load as long as the neutral is brought out to the disconnect whether it is actually used by the load or not?Why would a delta to delta transformer have an X0 terminal on the secondary side?
Because it is actually a delta to wye transformer (which could be used to feed a delta wired load as long as the neutral is brought out to the disconnect whether it is actually used by the load or not?
Or because it also contains a set of zig-zag windings to create a neutral point for the delta for some oddball reason?
There will still be a ground/bonding point for that transformer frame and other sheet metal whether it is connected to the secondary windings or not, but that should not properly be labelled X0 if not connected.
The X0 of a wye winding set should not be connected to anything if the secondary is supplying a corner grounded delta system.Would the X0 affect a corner grounded system?
Why would a delta to delta transformer have an X0 terminal on the secondary side?
I agree that it could be a 240V delta secondary... but the midwinding tap is usually marked X4.For lack of more detail, I assume this is a 480 delta to 240 delta.
It adds little cost when making a transformer like this to add the X0 terminal at the center point of one winding. This makes the unit more versatile in that you can use the X0 terminal to ground and bond the secondary as is required and you then have a 120/240 3 phase "high leg" secondary. Or you can leave the X0 not connected to anything and corner ground the secondary to be compliant (not usually the best choice).
Also if you use the transformer in reverse you just connect nothing to the X0, but then you have to run the 480 secondary corner grounded or ungrounded (neither is usually desirable but can be made compliant).
Can you post a picture of the nameplate?Why would a delta to delta transformer have an X0 terminal on the secondary side?
For lack of more detail, I assume this is a 480 delta to 240 delta.
I agree that it could be a 240V delta secondary... but the midwinding tap is usually marked X4.
This is typical texie. Just think how simple this would be should the NP information or a picture of the NP were to have been included in the OP.For lack of more detail, I assume this is a 480 delta to 240 delta.
It adds little cost when making a transformer like this to add the X0 terminal at the center point of one winding. This makes the unit more versatile in that you can use the X0 terminal to ground and bond the secondary as is reqired and you then have a 120/240 3 phase "high leg" secondary. Or you can leave the X0 not connected to anything and corner ground the secondary to be compliant (not usually the best choice).
Also if you use the transformer in reverse you just connect nothing to the X0, but then you have to run the 480 secondary corner grounded or ungrounded (neither is usually desirable but can be made compliant).
T... be a 240/120, 3ph 4w. Would not the centertap be identified as X0?
I stand to be corrected Jim. I guess I could be the only reason I could think of for an X0 termination on a "delta" which now concerns me. If it is in fact a delta where did they get an X0 from? Taking a wild guess they could have a 240y/138 which may be a drive transformer and they are assuming the 240v is a delta voltage. Simply asking just what the X1,2,and3 to X0 voltages are could explain a lot.Not according the standards in the industry. The center-tap would be X4.
If it is in fact a delta where did they get an X0 from? Taking a wild guess they could have a 240y/138 which may be a drive transformer and they are assuming the 240v is a delta voltage. Simply asking just what the X1,2,and3 to X0 voltages are could explain a lot.
Please provide us with a picture of the nameplate of the transformer as that would make it very simple to answer a lot of question. Providing verbal description often are prone to misinterpretation, assumptions and guesses.It's a 480v delta primary 240v delta secondary. The transformer is being used in a PV install. Beside the fact that inverter can only generate 3 phase 480wye it was hooked up anyway. The building it feeds is 240v corner ground delta. Voltage from the building read what it should for a corner ground system. Before we turned on the inverter I wanted to check the readings on the primary side just to be safe. H1 -G 520v H2-G 480v H3-G 208v. Didn't go phase to phase for fear of smoking my meter. The secondary is hooked up as X1-hot X2-grounded hot X3-hot. There is a terminal at the bottom of the transformer marked X0 but nothing is hooked to it. The taps on the primary side are all on the 480v tap. Why would I get such strange voltages? I thought it strange that there was an X0 on a delta and can't remember if it went to one winding or all of them.
The nameplate doesn't show an X0 :?