In delta-connected load, is "Ia+Ib+Ic=0" still valid?

[powersys]

By applying Kirchhoff's current law at the "floating" neutral point of a Y-connected load, "ia + ib + ic = 0" is obtained.

Is this "ia + ib + ic = 0" hold for a (balance) delta-connected load?

Thanks.

 

[jeffrey samuel]

mostly if the delta connection is not further connected to any the load the law holds good other wise the external current say il will also be included in your term that is all

 

[FvM]

Without a "supernatural" current path, how should we imagine a non-zero current sum? In fact, the current sum is also zero for an unbalanced load.

If you are sure at least about the first result in your post, you can derive the second by applying y-d transformation and equivalence of both circuits.

 

[powersys]

Thanks Jeffrey and FvM.

I'm confused with the assumptions/conditions made in the article below (https://en.wikipedia.org/wiki/Alpha–beta_transformation).

[1st]
The article states that "...In a balanced system Ia + Ib + Ic = 0..." In my opinion, this statement is misleading.
For example, as FvM mentioned, "Ia + Ib + Ic = 0" is also true for an unbalanced system.

[2nd]
The condition for "Iγ = 0" to be true is not because it is a balanced system. Iγ is not necessarily zero in a balance Y-connected system if the neutral point is grounded. Is "... Ia + Ib + Ic = 0 thus Iγ = 0 too general"?

[3nd]
Zero-sequence can flow in a delta-connected load or system. Therefore, in my opinion, "... Ia + Ib + Ic = 0 and thus Iγ = 0..." is not correct.


Please correct me if I'm wrong. Further, do you think the statement "In a balanced system Ia + Ib + Ic = 0 and thus Iγ = 0 and two of the phase currents suffice to compute the α and β components." needs to be corrected? If YES, how should we write it?

Thanks.

 

[FvM]

The "balanced system" reservation makes only sense, if an electrical path for a "Null"-component exists, in other words a four wire power supply. In a three wire supply, the currents are not necessarily balanced to each other (= have equal magnitude), but always sum to zero.