Vector group selection
Vector group selection
(OP)
Hi.. every body!
we want to install new power transformer, but we have problem.
My question about vector group. Is there any relation between the vector group and short circuit current. one engineer told me that if I want to use the power transformer in area near the generation, I sould select YNd1, because the short circuit current will be high, while in other areas too far from generation plants, YNd11 can be used because of the low level of short circuit current!
Is that correct?
we want to install new power transformer, but we have problem.
My question about vector group. Is there any relation between the vector group and short circuit current. one engineer told me that if I want to use the power transformer in area near the generation, I sould select YNd1, because the short circuit current will be high, while in other areas too far from generation plants, YNd11 can be used because of the low level of short circuit current!
Is that correct?






RE: Vector group selection
RE: Vector group selection
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If we learn from our mistakes I'm getting a great education!
RE: Vector group selection
But if there is no relationship, why sometimes YNd1 is used and other times YNd11. Is it just standard or there is any other reason for using different vector groups in different transformers.
RE: Vector group selection
In theory, any transformer may be connected for any vector group.
In practice there are some limitations. For example if a vector group is selected that requires a set of windings be changed from a delta configuration to wye or vice versa, the rated voltage will change.
Another practical issue may be grading of the insulation from end to end of some of the windings.
The selection of a vector group is often made to match existing transformers or system standards to facilitate parallel operation.
A question for those who are more familiar with vector groups:
Does the vector group of some transformers change if the transformer power flow is reversed? That is whether the transformer is used for step-up or step down?
Bill
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"Why not the best?"
Jimmy Carter
RE: Vector group selection
ANSI C57.12 and IEEE C57.12.00 specify that the angular displacement shall be 30 deg where LV phase vector lags the HV phase vector (Clock 1)whereas Clock 11 is specified by IEC 60076-1.Therefore you will see any trafo made in North America(NA)per ANSI is always clock 1 and any UK based transformers are Clock 11. But it does not prevent any NA ANSI trafo manufacturer to make a 12 clock transformer and any IEC trafo manufacturer (e.g. HYUNDAI)to make a Clock 1.There are so many HV substation installations in NA where the design has come from UK/Japan. In those places you will find Dyn11 or YNd11 as the case may be.
RE: Vector group selection
RE: Vector group selection
David Castor
www.cvoes.com
RE: Vector group selection
Please refer
1)section 5.6.2 of ANSI C57.12
2)section 5.7.2 of IEEE C57.12
3)section 6 of IEC 60076-1
Also please see what dpc has posted.
RE: Vector group selection
My copy of IEC 60076-1 doesn't make any stipulation in section 6, just gives some examples. I'll have to check if this is the most recent update. I don't have the IEEE standards available right now so I'll take your word for it.
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If we learn from our mistakes I'm getting a great education!
RE: Vector group selection
I will check the clauses mentioned and come back.