Three winding transformer

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SUMMARY

The discussion centers on the behavior of zero sequence currents in a three-winding transformer, specifically regarding the inability of primary currents to balance these currents due to the isolated neutral in a star-connected primary. Participants clarify that zero sequence currents are in phase and cannot flow back through the isolated neutral, which leads to an imbalance. The conversation emphasizes the importance of understanding Kirchhoff's Current Law (KCL) in analyzing the flow of currents in this configuration.

PREREQUISITES
  • Understanding of three-winding transformer configurations
  • Knowledge of zero sequence currents and their phase relationships
  • Familiarity with star-connected primary systems
  • Basic principles of Kirchhoff's Current Law (KCL)
NEXT STEPS
  • Research the implications of isolated neutrals in transformer design
  • Study the phase relationships of zero sequence currents in electrical systems
  • Explore the effects of line-to-neutral loads on transformer performance
  • Learn about balancing techniques for three-winding transformers
USEFUL FOR

Electrical engineers, power system analysts, and students studying transformer theory will benefit from this discussion, particularly those focusing on the behavior of zero sequence currents and transformer configurations.

ranju
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while studying the purpose of tertiary winding in the this 3-winding transformer , I'hv gone through a statement that " the zero sequence component caused by line-to-neutral load on secondary side cannot be balanced by primary currents as the zero sequence currents cannot flow in isolated neutral star connected primary".
Now first of all I wanted to know that the currents in secondary are balanced by primary as this is the basic thing I am not getting this and why can't primary currents balance the zero sequence component ??
And secondly why can't the zero sequence current flow in star-primary??
I am missing some basics , so please elaborate it..??
 
ranju said:
zero sequence currents cannot flow in isolated neutral star connected primary"

Isolated neutral... hmmmmm,,, you already know the answer...

What is phase relation between zero sequence currents?

What does KCL tell you about currents into that neutral node?
 
jim hardy said:
What is phase relation between zero sequence currents?
the zero sequence are all in same phase with each other & there's a zero phase displacement between them .. I am not getting why the primary currents can't balance the zero sequence current??
 
ranju said:
the zero sequence are all in same phase with each other & there's a zero phase displacement between them .. I am not getting why the primary currents can't balance the zero sequence current??
hmmmmm. all in phase? Do they all flow into or out of the the neutral in phase?

seems there's no way back out of neutral? You said it's not connected ... Kirchhoff says what goes in must come back out?
 
Last edited:

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