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Delta Wye Dyn1 not Dyn11
4

Delta Wye Dyn1 not Dyn11

Delta Wye Dyn1 not Dyn11

(OP)
I have been reading the following closed thread
http://www.eng-tips.com/viewthread.cfm?qid=41454

And then I found this pdf below.

http://www.labvolt.com/downloads/download/86379_F0...

as I understand this, the Delta Wye example shown on page 20 is a Dyn11 because the Secondary line to line voltage is leading the primary line to line voltage.

Now the next example on page 22 as I read the documents that is a Dyn7? transformer due to the 150 degree lag.

My question is in the US when I buy a transformer from someone like Sq. D
750KVA 480V 3 phase primary and a 120/208V Wye secondary.
http://products.schneider-electric.us/support/tech...

I read on here that a typicall US delta wye transformer is a Dyn1 with the secondary line to line voltage LAGGING the primary side line voltage by 30 degrees.

I like the Labvolt pdf because it included vector and time domain images to help me understand. If someone could help me understand how the dots are arranged in the US typicall transformer I would appreciate it.
thank you for your time and have a good day

RE: Delta Wye Dyn1 not Dyn11

The ANSI standard for delta-wye or wye-delta connections is that the low side lags the high by 30 degrees. Maybe someone else can answer your other question - I don't really understand it.

RE: Delta Wye Dyn1 not Dyn11

(OP)
SO reading the link you gave I see page 13 seems to be the trick. It looks like the dot connection on the delta primary is the difference unless I am missing it.
Is there a free circuit simulation software that has transformer models? I would like to play with these connections and watch the time domain effects.
As I see this the Primary line to line in the Dy11 or Dy1 is in phase with the Line to neutral voltage, the difference is L-L of the Primary to L-L of secondary.
thanks for your help. any thoughts or examples is appreciated.

RE: Delta Wye Dyn1 not Dyn11

All you really need to do is draw out the phasors. Just remember that there is a pair of windings on each leg of the core regardless of how the three coils are connected the primary and secondary. The only thing happening is reconnecting phases and polarity of one set of windings wrt to the other. I really don't see what you are going to learn from a time domain analysis.

There is ATP (http://www.emtp.org/) if you really want to bury your pick into this. I get the feeling maybe you are over-thinking it. There will always be a phase shift in a delta-wye connection.

Regards,

dpc

RE: Delta Wye Dyn1 not Dyn11

(OP)
has anyone tried to make transformers in LTSpice using ideal inductors and spice directives to define the coupling?
I found a tutorial on this but I was having some trouble. It errored saying that the nodes were floating, but I dont want to ground the delta.
Thanks.
http://cds.linear.com/docs/LT%20Journal/LTMag-V16N...
any help is appreciated.
Thank you to unclebob and stevenal I think the links you provided were very helpful.

RE: Delta Wye Dyn1 not Dyn11

I recall building an ideal transformer using the student version of Pspice a few years back. I believe I used voltage controlled voltage sources and current controlled current sources. I also recall that floating nodes were not allowed. You need to add a high value resistance to ground.

RE: Delta Wye Dyn1 not Dyn11

(OP)
do real transformers exibit a deviation from the perfect 30° shift.
For example if I measure a transformer in service would I see 29.8° due to the realities of a real machine vs the theoretical? or would it be 30.2?
I am asking because if I parallel 2 transformers and there was a slight difference I would think that would make an uneven sharing of the load.

thanks to everyone for your help,

RE: Delta Wye Dyn1 not Dyn11

Hi,

I would like to ask simple question here.

Is there difference between Ynd1 and Ynd11 ?
Is it usable to use Ynd11 to replace Ynd1 power transformer ?


Regards,
Linspire

RE: Delta Wye Dyn1 not Dyn11

I believe there's a FAQ on this forum that explains it. But given the right connections on both sides of the transformer, any Ynd can be connected to become Ynd1, Ynd3, Ynd5, Ynd7, Ynd9 or Ynd11. There is a set of rolls and swaps that will convert from any one of those possibilities to any other one of them. The even numbered vector relationships are not available in Ynd (or Dyn) regardless of how clever you are in connecting int.

RE: Delta Wye Dyn1 not Dyn11

How about if the my place electric utility used to be Ynd1 for their system. Is acceptable for them to purchase Ynd11 instead of Ynd1, while the other equipments ( surge arrester, earthing transformer, disconnector, etc ) are used same as Ynd1 transformer system.

RE: Delta Wye Dyn1 not Dyn11

(OP)
To Davidbeach's point, I think that is what I am trying to understand. Exactly how to I rearrange the wires (rools and swaps) to achieve different phase relationships. I find myself in front of a transformer with the client and the EC asking me exactly which wire goes where. I cant just say well rewire the delta and secondary to get a different phase angle. I also don't know how to configure things to get Ynd3 or Ynd9, but I thanks to others here now understand the 1,5,7,11 relationships.
To the point that was made eariler, it may seem like I am getting to far into things(so to speak) but when all eyes are on you and the transformer in question is 7.5 MVA and built in Croatia the cost and responsibilty that is on one's shoulders makes you double and triple check your understanding.
That is why I want to simulate these things electronically before I ruin a custom wound transformer. The language barrier from the manufacturer has put me in the hot seat to direct the EC.

RE: Delta Wye Dyn1 not Dyn11

I wouldn't even consider making this determination in the field with contractor looking over my shoulder. This is not something that is done on a routine basis. You need to take adequate time to evaluate the existing conditions, what the end result needs to be, and then determine how to achieve it. Then get another engineer to review what you come up with. If the contractor has to wait a day or two, then that's just the way it is. There are a lot of issues to consider before you start changing the vector orientation of a transformer. This is not the same as bumping motor to check the rotation.

RE: Delta Wye Dyn1 not Dyn11

Dpc gives very sound advice, as always.

From your handle, I am going to guess you are either in Wisconsin or you are from Wisconsin. If this job is in the US, you really have a duty to design the connection on paper, seal it, and sign it.

No matter how much the pressure, I would refuse to make that call on my feet. I would just tell them that I would return with a signed and sealed wiring diagram in two days. Waving your hand to indicate how the wiring is to be done for a connection that is very valuable and requires thought will never help when push comes to shove.

Put your foot down on them. Draw it up, get some peer review if you are uncomfortable. Then hand it over.

Best to you,

Goober Dave

Haven't see the forum policies? Do so now: Forum Policies

RE: Delta Wye Dyn1 not Dyn11

Hmm there's difference right between Ynd and DYn rite..from the FAQ, I read these stated Dyn,Dd0 and Yn15, doesnt mention Ynd1 or Ynd11

RE: Delta Wye Dyn1 not Dyn11

Neutral brought out - actually means there is no neutral connected to winding ?

RE: Delta Wye Dyn1 not Dyn11

Linspire,
It is true the FAQ deals with DY transformers rather than YD. I thought perhaps the engineers here might find the concept useful and be able to apply it to their specific situations.

RE: Delta Wye Dyn1 not Dyn11

(OP)
In response to some of the above, we are doing a project where the transformer is coming from croatia. It has 4 delta windings at 3160 and a single wye winding that is connecting to the 13.8KV grid.
The 4 windings are connected to 4 inverters paralleled to improve performance.
The unit is coming as a tank, a core, and then we have to wire the windings to the terminal bushings and connect the thermocouples. then we will fill it with oil with the help of a vacuum pump.

When we took on this project we felt when we required the drive manufacturer to provide the grid side(7MVA Delta/ungrounded Wye) and the test side transformer(the transformer described above) I would recieve an assembled and factory tested unit.
It turns out I was mistaken and that putting a core in the tank, connecting the windings to the correct terminal bushings and all the other work was part of "Installation"
I am working on getting drawings from the transformer manufacturer to make sure all the windings are arranged correctly.
I will be grounding the test side Wye winding.
The input side(7MVA) isnt grounded becuase their drive derives a pseudo ground point and solidly grounding it would prevent them from doing what they want. I am using 15KV 100% rated cable on the 3160 side because this pseudo ground is apparently not perfect so they do see some voltage "abnormalities" on the input side. They are using the ungrounded wye inductance (10.6%) impedance as the first L of their LCL harmonic filter.

I do appreciate all the input and I am working to understand this before I am on site supervising the electrician, but at the end of the day the EC wont take any responsibility, and they shouldn't.
The links provided have been very helpful. have a great thanksgiving.

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