3W Transformers
3W Transformers
(OP)
This may sound simple to others but I will take a shot in asking. What are the applications of a 3 winding transformers and when they are supposed to be applied. If three voltage levels pose as an advantage, wouldn't be suitable to use two winding transformers instead? What are the advantages and disadvantages?
GO PLACIDLY, AMIDST THE NOISE AND HASTE-Desiderata






RE: 3W Transformers
How about a concrete example so we can provide a worthy answer. Hmmmmmm?
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: 3W Transformers
Economic - one three-winding transformer can do the work of two two winding transformers in many situations. On a $/kVA basis, the 3-winder will be less expensive (for large kVA ratings).
Short circuit ratings - splitting the low side into two windings will reduce the available SC current and can help in some situations.
You can also get two different voltages on the secondary and tertiary windings.
On paper, they can look pretty attractive, but they are tough to replace when they fail and a single failure will generally knock out more of the system.
RE: 3W Transformers
May I ask any refence or link that would give me a deeper view on this? Thanks
GO PLACIDLY, AMIDST THE NOISE AND HASTE-Desiderata
RE: 3W Transformers
Three winding and auto-transformer are not the same thing at all, except that nearly all power system auto-transformers include a third winding as a delta tertiary. You can have three windings and not have an auto-transformer. Generally a step of one or two standard voltages (up to about 3:1 on voltage) will be auto-transformers for economic reasons. Larger voltage steps typically are not auto-transformers.
An industrial buck/boost transformer is a two winding auto-transformer.
RE: 3W Transformers
And that is so. If there are two Y windings, your triplene harmonics have a high impedance that creates problems. Putting a tertiary D winding "hangning" makes the triplenes seeing a low impedance (3x120=360, so a D winding is a short to them). And that helps a lot. But this is only necessary if you have primary and secondary in Y. Usually, you have a primary D and a secondary Y. Then, the tertiary is not needed.
Gunnar Englund
www.gke.org
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