powersys
Advanced Member level 1
I would like to discuss the underlined sentences in the text below.
[1] As triple harmonic currents have zero phase sequence they cannot exist in a three-phase balanced form unless there is a neutral return path.
[2] The rectifiers normally included in UPS equipments are of the three-phase bridge type; at there is no neutral connection there will be no significant triplen harmonic currents.
Questions:
[Q1] Kindly refer to [1] above. If the three-phase system (Y-connected and without neutral return path) is unbalanced, will triple harmonic currents appear in phase or line currents?
[Q2] Kindly refer to [2] above. The author said "no significant", which means a three-phase (Y-connected) with no neutral connection can has "little" triple harmonic currents. If my interpretation is correct, would someone please advise how these "little" triplen harmonics occurs?
Thanks
[1] As triple harmonic currents have zero phase sequence they cannot exist in a three-phase balanced form unless there is a neutral return path.
[2] The rectifiers normally included in UPS equipments are of the three-phase bridge type; at there is no neutral connection there will be no significant triplen harmonic currents.
Questions:
[Q1] Kindly refer to [1] above. If the three-phase system (Y-connected and without neutral return path) is unbalanced, will triple harmonic currents appear in phase or line currents?
[Q2] Kindly refer to [2] above. The author said "no significant", which means a three-phase (Y-connected) with no neutral connection can has "little" triple harmonic currents. If my interpretation is correct, would someone please advise how these "little" triplen harmonics occurs?
Thanks