3 phase 480 corner grounded delta

[domnic]

3 Phase grounded delta three wire 480 volt to single phase 240/120 volt transformer to 200 amp panel , does the 480 volt grounded phase always come in contact with the neutral of the 200 amp panel through bonding ?

 

[iwire]

3 Phase grounded delta three wire 480 volt to single phase 240/120 volt transformer to 200 amp panel , does the 480 volt grounded phase always come in contact with the neutral of the 200 amp panel through bonding ?

Indirectly yes.

 

[kwired]

And that 480 volt system grounded conductor is in contact with the grounded conductor of the source supplying it - from POCO's is often a system that is 7200 volts to ground.

 

[infinity]

Why a 3Ø primary and 1Ø secondary?

 

[domnic]

Why a 3Ø primary and 1Ø secondary?

I need 240 volt single phase .

 

[ggunn]

I need 240 volt single phase .

Then you will use only one or two of the 480/277 phases, not all three.

 

[domnic]

Grounded phase

Grounded phase

No matter witch two of the 3 phase transformer lugs I use the grounded phase will be in contact with the neutral in the 120/240 panel.

 

[ggunn]

No matter witch two of the 3 phase transformer lugs I use the grounded phase will be in contact with the neutral in the 120/240 panel.

Well, OK, but since the primary and secondary are only connected magnetically it doesn't make any difference. You could, for example, feed 480V corner grounded to the primary and have 208/120Y on the secondary with the center of the wye grounded.

 

[infinity]

No matter witch two of the 3 phase transformer lugs I use the grounded phase will be in contact with the neutral in the 120/240 panel.

The corner ground has a single grounded phase what if you use the two ungrounded phases?

 

[ggunn]

The corner ground has a single grounded phase what if you use the two ungrounded phases?

It doesn't matter. The transformer secondary doesn't know or care if one of the primary phases is grounded. Grounding is a DC quantity and transformers do not pass DC.

 

[iwire]

It doesn't matter. The transformer secondary doesn't know or care if one of the primary phases is grounded.

I agree

Grounding is a DC quantity

I am puzzled.

 

[ptonsparky]

I am puzzled.

I feel better, so am I.

 

[electrofelon]

No matter witch two of the 3 phase transformer lugs I use the grounded phase will be in contact with the neutral in the 120/240 panel.

That is correct. Every transformer that has a grounded system on both sides will have the grounded conductors from both systems bonded together.

 

[Ingenieur]

I agree



I am puzzled.

Zero sequence?

a xfmr X0 is actually the sec zero sequence grounding reactance
it is infinite on the primary

 

[ggunn]

I agree



I am puzzled.

Ground is an offset of zero volts DC and as such is not passed by a transformer. That may not be mathematically rigorous but it gets the point across. To me, anyway.