Third Harmonics Wye-Wye Connection

Dear all,

In your case, there is no 3rd harmonic current in both primary and secondary.

Even the neutral at secondary is earthed, the impedance against 3rd harmonic current is very high and the secondary winding will appear as a choke coil against 3rd harmonic.

Often, Wye-Wye transformer is equipped with embedded delta to create 3rd harmonic circuit. If there is no 3rd harmonic circuit in a transformer, secondary voltage will include 3rd harmonic.

Regards

"Often, Wye-Wye transformer is equipped with embedded delta to create 3rd harmonic circuit. If there is no 3rd harmonic circuit in a transformer, secondary voltage will include 3rd harmonic"

embedded means tertiary true? saying wye-wye you mean what ? (about neutral-earth connections I ask )

why does a delta create 3.harmonic? as far as I know this eliminates it..

Dear all,

Embedded Delta is called as stabilizing Delta. Actually this is a tertiary, but there is no load to be connected. If you purchase a Wye-Wye transformer, it may be Wye-Wye-stabilizing Delta. This Tertiary is normally does not appear in single line diagrams since there is no external connection.

Regards

so pls tell me, if you have a wye(grounded) -wye(ungrounded)

and wye (ungrounded )- wye (grounded) transformers in turn(for both cases I ask separately ), what would you say about triplen harmonics? pls give some detail, do they flow or has some other effect on the windings?

Dear all,

Talking about the current follow, triplen harmonics (odd, multiple of 3rd harmonic) will behave same as 3rd harmonic. Or you may call them as zero phase current.

If the power source is on primary side of a transformer, the secondary will have a 3rd harmonic voltage caused by hysteresis of the core. To reduce the 3rd harmonic voltage at secondary, normally, a 3 phase transformer has a delta winding in it. The delta winding creates a short circuit for the 3rd harmonic and it is consumed in the delta winding.

If there is no delta in a three phase transformer, such as Wye-Wye winding, a secondary current must induce a primary current. If the primary current has not current path, secondary current will not flow into the secondary winging.

The summary is following.

Wye (Grounded) - Wye (Ungrounded) High impedance to 3rd harmonic.

Wye (Ungrounded) - Wye (Grounded) High impedance to 3rd harmonic.

Wye (Ungrounded) - Wye (Ungrounded) High impedance to 3rd harmonic.

Wye (Grounded) - Wye (Grounded) 3rd harmonic current depends on external impedance.

Regards

I need a little more information from you before I answer your question.

1. Is the primary star side neutral connected to its source? (even though it is unearthed)

2. Is this source of the primary winding earthed or un-earthed?

3. Is the secondary star neutral distributed? Or is it only earthed solidly at the source?

4. What are the type of loads connected to the secondary star side of this transformer? (include both single phase loads as well as three-phase loads)

you can try to give some information of the main cases, Please tell me how triplen harmonics cancel out for a wye wye (while one of them is earthed ) at the lines while they have to add to each other but since they cant find a path to flow they do not occur but cancel out.?