Polarity of 3p core transformer

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SUMMARY

The discussion centers on the application of a 380V, 3-phase core type transformer used as an AC line choke in a Variable Frequency Drive (VFD). It confirms that connecting the R phase of the supply to any winding is permissible, provided the windings are consistent and not swapped end for end. Maintaining balanced phase currents is crucial to ensure a sum zero magnetic field in the shared core, which is essential for optimal transformer performance.

PREREQUISITES
  • Understanding of 3-phase transformer configurations
  • Knowledge of Variable Frequency Drives (VFDs)
  • Familiarity with inductance properties in electrical systems
  • Basic principles of magnetic fields and phase balance
NEXT STEPS
  • Research 3-phase transformer wiring configurations
  • Learn about the operation and benefits of Variable Frequency Drives (VFDs)
  • Explore inductance properties and their applications in electrical systems
  • Study the principles of magnetic field balance in transformers
USEFUL FOR

Electrical engineers, power system designers, and technicians working with transformers and Variable Frequency Drives (VFDs) will benefit from this discussion.

Amith Menon
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I have a 380V,3 phase core type transformer which is being used as AC line choke in the incomer of a VFD.As we are using only the inductance property of the transformer,I was just wondering whether we could connect R phase of the supply to any winding and then follow the phase sequence accordingly.
Thanks in advance
 
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Yes. The only important thing is to make sure that the three windings are consistent and that one is not swapped end for end. For balanced phase currents, the shared core should have a sum zero field.
 
Most likely this can only be answered by an "old timer". I am making measurements on an uA709 op amp (metal can). I would like to calculate the frequency rolloff curves (I can measure them). I assume the compensation is via the miller effect. To do the calculations I would need to know the gain of the transistors and the effective resistance seen at the compensation terminals, not including the values I put there. Anyone know those values?

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