Is the Transformer Short Circuit Calculation Correct?

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SUMMARY

The discussion focuses on calculating the short circuit current at transformer terminals using a specific example: a 6.6kV/400V, 3 Phase, 10MVA transformer with an impedance of 8%Z. The calculated full load current (FLC) is determined to be 14,434A. By applying the formula for short circuit current, the participant arrives at a value of 180kA, confirming the calculation method and principles involved. The approach emphasizes the importance of understanding transformer impedance in short circuit scenarios.

PREREQUISITES
  • Transformer impedance calculations
  • Understanding of three-phase power systems
  • Short circuit current analysis
  • Basic electrical engineering principles
NEXT STEPS
  • Study transformer short circuit analysis techniques
  • Learn about the impact of transformer impedance on fault currents
  • Explore the use of software tools for short circuit calculations
  • Review IEEE standards for short circuit current calculations
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Electrical engineers, power system analysts, and anyone involved in transformer design and fault analysis will benefit from this discussion.

fonz
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Ok I've read a lot of articles and seen a lot of different ways of calculating the short circuit current at the transformer terminals.

So I'm going to apply my own intuition and see if I can arrive at the correct value if someone could please confirm my answer.

6.6kV/400V
3 Phase
10MVA
8%Z

By definition %Z is the % of Vp that causes FLC under short circuited conditions.

FLC = 10000000/(1.732*400) = 14434A

so 8% 6600V = 528V

6600/528 = 12.5

So 12.5*11434= 180kA

Is this correct? I know I've simplified it and rounded generously but I'm just trying to get the general principle down.

Thanks
Dan
 
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