Zero sequence current in delta connection

Posted on 01.06.2018 by Bruna
No zero sequence currents can flow in the lines connected to a delta connection as no return path is available for these currents. Either the star connection must be neutral grounded or a double line ground fault LLG, or single line to ground fault SLG must occur if it is a delta connection. The above equation shows that there is no zero sequence current present in the delta connection. Let us now consider various types of transformer connections.
I don't quite understand the method. My question is, how or why does it give us the negative and zero sequence impedance. I've read that for delta connections, the zero sequence currents are zero on the lines but are present within the phases. Zero sequence currents can, however, flow in the legs of a deltasuch currents are caused by the presence of zero sequence voltages in the delta connection. A balanced delta connected load with equal phas. The zero sequence current of phases a, b and c are equal in magnitude and in phase with each other. The delta connected winding is shown in the figure below.
In delta connected winding no zero sequence currents flow in the lines because there is no return path for these currents. It is circulated in the phase windings of the delta connection as shown in the figure below. Similarly, by applying KCL at nodes B and C, we have. When a terminal is open in ?, then there is no chance of flowing currents with basic frequency around the closed mesh. The equation below express the zero-phase sequence current, Delta-Connected Winding. The zero sequence currents are produced due to the existence of zero sequence voltage.