In this image what would be different if it were a Delta to Delta Trafo?????

Status
Not open for further replies.
iwire said:
No one has said otherwise have they?
Click to expand...

No, not explicitly. You know the point I was trying to get across: that a three wire feed does not necessarily mean it lands in a delta connected winding. Sure, delta primaries are by far the most common in the LV electrical construction field.



I do not know what that means.
Click to expand...

see above. It may and often does imply a delta winding in common usage. I personally dont like that phrase as I have found it to cause confusion frequently. I prefer using the terms delta and wye. Maybe you haven't ever experienced confusion over the term 3-wire in reference to delta and wye connections. Thats ok , YMMV.



We could have a lot of things, but we don't have a Wye / Wye transformer in the OPs picture.
Click to expand...

I obviously found it ambiguous. Sorry that bothers you so much.

I second the question.

What I posted is most certainly standard transformer information.
Click to expand...

I wasnt referring to you designation, I was referring to the drawing in the OP. I dont usually see transformers described that way and found it ambiguous especially considering the OP presumably drew it and called it a wye. Maybe his question related to connecting only three wires to a wye winding.....
 
don_resqcapt19 said:
The OP asked what would be different if the transformer was delta/delta.
Click to expand...
Many of us got caught up in the primary, partly because it seems to get asked a lot about a wye connected load needing a neutral connection, they don't always need a neutral connection.

roger said:
And post #3 pretty much answered that considering there is a grounded conductor shown.

Roger
Click to expand...
And if we know it is delta secondary and there is a neutral then it has to be a system with a high leg. The main difference in the drawing that relates to codes would be that the high leg needs to be identified with orange on the secondary side wherever it is present with the neutral conductor.
 
kwired said:
And if we know it is delta secondary and there is a neutral then it has to be a system with a high leg. The main difference in the drawing that relates to codes would be that the high leg needs to be identified with orange on the secondary side wherever it is present with the neutral conductor.
Click to expand...
So you're just repeating what I said and adding specifics.



Roger
 
kwired said:
Many of us got caught up in the primary, partly because it seems to get asked a lot about a wye connected load needing a neutral connection,
Click to expand...
I'm calling it out because of the single voltage of the primary. If you can go around your area and find a Wye-Wye transformer look at the name plate and take note of the primary and secondary voltages. It may be easiest to find it on a Padmount verses a Dry Type.

Roger
 
roger said:
I agree with Bob.

Why do you think the transformer is a YY?

If the secondary was a Delta the voltage would not be 120/208 and the colors in the secondary panel would be wrong as far as current code.

Roger
Click to expand...

There would be nothing wrong with the colors if the secondary was a 4 wire delta.
 
don_resqcapt19 said:
There would be nothing wrong with the colors if the secondary was a 4 wire delta.
Click to expand...

roger said:
Ok, I'm open for your explanation.

Roger
Click to expand...

The colors used in the drawing would be acceptable to NEC. The high leg still "shall be durably and permanently marked by an outer finish that is orange in color or by other effective means". Most will just change the color of the high leg to orange, but it could have both red and orange markings on it. Then there is still the "other effective means" as a possibility.
 
roger said:
Correct, and there is no orange in the secondary, it is even spelled out as black, red, blue. Roger
Click to expand...
It was asked what would (need) to be different if the secondary were delta. If the secondary were delta there would need to be either a high leg, a grounded phase, or it would be an ungrounded system meaning no white or gray marked conductor at all.
 
kwired said:
It was asked what would (need) to be different if the secondary were delta. If the secondary were delta there would need to be either a high leg, a grounded phase, or it would be an ungrounded system meaning no white or gray marked conductor at all.
Click to expand...
And since a grounded conductor is shown in the secondary of the illustration it would be a center grounded Delta which means it would have a "High Leg".

Roger
 
roger said:
And since a grounded conductor is shown in the secondary of the illustration it would be a center grounded Delta which means it would have a "High Leg".

Roger
Click to expand...

I know we are going round and round here, but the secondary looks wye to me. I have never seen a three phase 208 wired high leg. 104V phase to neutral on two legs and 180V high leg to neutral? That would be weird.
 
ggunn said:
I know we are going round and round here,
Click to expand...
Yes we are.
ggunn said:
but the secondary looks wye to me.
Click to expand...
It is and the OP wants to know what would be different if it were a Delta. So given the fact that there are three ungrounded and one grounded conductor present in the secondary panel it would be indicative of a Center Grounded Delta.

ggunn said:
I have never seen a three phase 208 wired high leg.
Click to expand...
Nor have I

ggunn said:
104V phase to neutral on two legs and 180V high leg to neutral? That would be weird.
Click to expand...
Yes it would be.

Roger
 
roger said:
It is and the OP wants to know what would be different if it were a Delta. So given the fact that there are three ungrounded and one grounded conductor present in the secondary panel it would be indicative of a Center Grounded Delta.
Click to expand...

Just an interesting observation: There are different ways to interpret and answer the original question. You take the angle of "this is the conductors we have, so if we keep those, what kind of delta fits that." I take the angle of "ok a delta, well erase the secondary stuff you have there and here are the options..." (as I did in post #6). Im am not saying one way of addressing the question is more right or wrong, just noting the difference. Similarly with the transformer designation in the drawing, I gave the OP words more weight and took into account that the drawing was not say drawn up in autocad. Others treated the drawing as gospel. Again, I am not saying one reading of the OP is more correct, just interesting to see how different people analyze and interpret things.

Regarding transformer designations, I'll retract the "industry standard" comment. I guess I dont really know if there actually is a specific "industry standard" in terms of the use of the words "delta" and "3-wire". I did do some digging though. I looked at a website that sells used transformers and they have photos of the data plates on almost every one. http://www.philipsbrothers.com/. About half of the delta primary padmounts just had a single voltage on the data plate. The other half had the voltage and the word delta. Of course they all had the phasor diagram on the dataplate. All of them said the voltage and the word delta in the verbal description. I didnt see any use of the term "3-wire"

Just today I came across an example of why I like to see the word "delta"/ 1.33 MW PV project plan set. Drawn/stamped by an EE. Also had third party review. Transformer shown as 12.47-480 volt, but its a wye-wye. You cant assume everything will denote a transformer correctly.
 
electrofelon said:
No, not explicitly. You know the point I was trying to get across: that a three wire feed does not necessarily mean it lands in a delta connected winding. Sure, delta primaries are by far the most common in the LV electrical construction field.
Click to expand...

No, I do not get your point, I am lost why, when a question is posted with a picture and designation of a transformer you are talking about other transformers.


see above. It may and often does imply a delta winding in common usage. I personally dont like that phrase as I have found it to cause confusion frequently. I prefer using the terms delta and wye. Maybe you haven't ever experienced confusion over the term 3-wire in reference to delta and wye connections. Thats ok , YMMV.
Click to expand...


See above? :?

What phrase? :huh:



I obviously found it ambiguous. Sorry that bothers you so much.
Click to expand...

Bothered no.

Confused why you find standard terminology ambiguous, yes.



I wasnt referring to you designation, I was referring to the drawing in the OP. I dont usually see transformers described that way
Click to expand...

Have you looked at transformer labeling? :huh:


This thread has been a cluster .... and the OP has not been back. :D
 
electrofelon said:
I doesn't say "delta". In jargon, "3 wire" usually means delta. Also considering the nature of the sketch and the op question, I could see 3 wire referring to how many conductors are attached to the primary.
Click to expand...

A wye ungrounded primary with a wye grounded secondary would be a very unstable connection, to the point of impractical. The 120 volt loads would dim and brighten as though the secondary neutral was never connected.


electrofelon said:
I think it is an important concept for those who are learning that 1) you can connect three wires to a wye supply or source 2) "x wire" and delta wye connections refer to different things 3) one could have a wye connection but not have access to the wye point.
Click to expand...


Correct, if the primary wye always remained 100% balanced as with a heating load where each coil is an even resistance or an ungrounded wye secondary. As soon as you connect ground or load to the secondary transformer neutral you must bring a neutral to the primary terminal.


And FWIW, moving away from this thread in general, but Y ungrounded Y ungrounded is not a preferred connection in the POCO world due to voltage stress/voltage fluctuations. Transformers are none linear, and when switched on the coils do not have equal impedances resulting in voltage shift between the H0 and earth. This shift can reflect in the secondary voltages.
 
Last edited:
iwire said:
No, I do not get your point, I am lost why, when a question is posted with a picture and designation of a transformer you are talking about other transformers.





See above? :?

What phrase? :huh:





Bothered no.

Confused why you find standard terminology ambiguous, yes.





Have you looked at transformer labeling? :huh:


This thread has been a cluster .... and the OP has not been back. :D
Click to expand...

I believe my post #34 answers most of your questions. If not, I'm sorry, I am giving up on trying to convey my thought process.
 
Status
Not open for further replies.
Top