electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
transformer primary bushing confusion
- Thread starter electrofelon
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Do you have a clear picture of the nameplate?
ATSman
ATSman
- Location
- San Francisco Bay Area
- Occupation
- Electrical Engineer/ Electrical Testing & Controls
From what I see it looks like a single phase HV primary and a secondary with a center tap on X2.
Send us a pic of the nameplate.
Send us a pic of the nameplate.
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
Unfortunately I have not been able to get a picture of the nameplate, that is the problem. I do not have the unit. I will try further next week.
Yes, I concur. The question is the primary bushing arrangement. I am not a MV guy, but from by experience, H1A and H1B bushings implies it is a loop feed grounded neutral unit. IF it was a delta primary, I would expect the bushings to be H1 and H2 if it was radial feed, or for loop feed H1A and H2A for primary in and H1B and H2B for primary out.. Now that I think about it though, I dont recall ever seeing a small single phase padmount with loop feed bushings....
ri
That certainly is what it looks like. I tried to blow up the NP which appears to be in the center but the picture resolution is poor.
It probably has a 2400v primary with a 240/120 1ph/3w secondary fitted with provisions for load break elbows on the primary of course.
ATSman
ATSman
- Location
- San Francisco Bay Area
- Occupation
- Electrical Engineer/ Electrical Testing & Controls
loop feed grounded neutral unit....??? not sure what what you mean with regard to the primary of a transformer.
Do not let the labeling confuse you. Two HV terminals indicate single phase. In which case "delta primary" has no meaning, only in 3 phase windings. What I would do is apply 120v on the primary H1A & H2A(gradually with a variac would be ideal) and measure the voltage at the x terminals. From these readings you could determine the winding configuration and make a diagram of what you have. But as far as putting it in service you would still need to know the voltage rating of the primary either from nameplate or contact the manufacturer with the cat or model# of the unit. What are you trying to do with it?
I just re-read your post and connected the 2400V to the "delta" you mention. This may be a 4160V, 3 phase system made up of (3) single phase units ! In this system the primaries of the 3 units are connected in delta fed from a 3 phase 4160V source (4160/sq rt of 3 = 2400V.) That would make the most sense of what you have
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big john
Senior Member
- Location
- Portland, ME
I don't really understand the context of your question regarding delta/wye, but I will say with 99% certainty that picture shows a single-phase loop-feed transformer with a 120/240V low-side.
In addition to the bushing designations, you can see a single fuse jack in the upper left that isolates the primary from the loop. If this connected to multiple phases, you'd have multiple jacks.
And you can see the bond strap on X2 that would be your low-side center tap.
In addition to the bushing designations, you can see a single fuse jack in the upper left that isolates the primary from the loop. If this connected to multiple phases, you'd have multiple jacks.
And you can see the bond strap on X2 that would be your low-side center tap.
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
Thanks for all the replies. No offense, but I am a bit surprised no one seems to understand what i am saying. I dont think my lingo is unusual. I know some folks only see MGN systems. Let me clarify a few things:
1. In regards to delta and wye, I am referring to the system this single phase transformer is fed from.
2. Delta assumes two ungrounded primary conductors, in which case this transformer would have two bushings.
3. Wye assumes a grounded neutral system, in which case this transformer is fed with 1 grounded and 1 ungrounded conductor and therefore 1 bushing.
4. If the transformer was for a delta system as purported , it should have two bushings for radial feed, or 4 for loop feed.
5. To me it looks like it is to be served L-N from a grounded neutral wye system (1 bushing) and has a second bushing for loop feed.
6. If it was indeed for a delta system, I would expect the bushings to be labeled "H1A" and "H2A" (or probably without the A letters at all unless it was loop feed, in which case there would be a B set)
1. In regards to delta and wye, I am referring to the system this single phase transformer is fed from.
2. Delta assumes two ungrounded primary conductors, in which case this transformer would have two bushings.
3. Wye assumes a grounded neutral system, in which case this transformer is fed with 1 grounded and 1 ungrounded conductor and therefore 1 bushing.
4. If the transformer was for a delta system as purported , it should have two bushings for radial feed, or 4 for loop feed.
5. To me it looks like it is to be served L-N from a grounded neutral wye system (1 bushing) and has a second bushing for loop feed.
6. If it was indeed for a delta system, I would expect the bushings to be labeled "H1A" and "H2A" (or probably without the A letters at all unless it was loop feed, in which case there would be a B set)
I've understood what you've been saying, asking all along. I just cannot contribute any information beyond what you've already surmised.
Nameplate, nameplate, nameplate!
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
I've understood what you've been saying, asking all along. I just cannot contribute any information beyond what you've already surmised.
Nameplate, nameplate, nameplate!
I suppose another way, perhaps better, to specify system and transformer configuration would be to state the voltage and number of bushings.
Yes I will try to get nameplate data this week and I'll keep y'all posted!
Tony S
Senior Member
- Location
- Resting under the Major Oak UK
With a Y primary this would give an open delta secondary.
wwhitney
Senior Member
- Location
- Berkeley, CA
- Occupation
- Retired
Do I misunderstand, or does "loop feed" in this context mean that H1A and H1B are internally connected?
Cheers, Wayne
Cheers, Wayne
H1A, H1B, and one side of the primary winding are internally connected... or should be... but I prefer to verify by way of the NAMEPLATE. :happyyes:
big john
Senior Member
- Location
- Portland, ME
You know it's's a grounded single-phase can and that virtually all of those are fed from wyes.
Looking at the nameplate isn't going to clear up anything additional: 2400V systems exist in both delta and wye.
Looking at the nameplate isn't going to clear up anything additional: 2400V systems exist in both delta and wye.
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electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
Ok found out that the unit is indeed for a grounded wye not a delta. The second bushing is just a feed thru. His original description was poorly worded. Thanks everyone for your input
ATSman
ATSman
- Location
- San Francisco Bay Area
- Occupation
- Electrical Engineer/ Electrical Testing & Controls
Xfmr Terminal Nomenclature
Xfmr Terminal Nomenclature
EB
Not sure how that has to do with this transformer in the pic. Explain feed thru.
Can you draw a diagram of how the system is connected. Sorry if it is elementary to others.
Xfmr Terminal Nomenclature
EB
Not sure how that has to do with this transformer in the pic. Explain feed thru.
Can you draw a diagram of how the system is connected. Sorry if it is elementary to others.
Looks like you have something like this if others would like to read up on it:
http://www.howard-ind.com/HowardTransformers/SinglePhasePadMountANSIType2Detail.asp
It's a single phase ANSI Type 2 MV transformer.
The two bushings are just connected together inside the transfomer. Used by the utility to connect more than one transformer in parallel without making splices or using "T's". One bushing is used for the input, and the other is used to connect the next transformer downstream.
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
A "loop feed" Transformer or "feed thru" bushing could be used for an alternate source of supply, or to feed another transformer. For example, a utility could use the feed thru to feed another transformer instead of running amother drop from a pole. In the pic, the two bushings are common.
I am still not sure of a few things about tranny designations in general. Look at this text from the link pv noob posted
High-Voltage Ratings 4160GrdY/2400 through 34500GrdY/19920 or
2400/4160Y
Does 4160grdY/2400 mean it's a 2400 volt primary with one bushing? I assume so. So what does 2400/4160Y mean? 2400 volt but 2 bushings?
kwired
Electron manager
- Location
- NE Nebraska
All it is saying is the ANSI type 2 is made in those voltage ranges, you still need to look at the nameplate of your particular unit to see it's rating.
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