I am performing an arc flash study and getting very high incident energy values. A few things I need clarification on:
Arc Duration: Since the main switch is fed by unprotected consumer mains, I have used the 2-second rule for both arc duration and reduced arc duration. Does this approach seem reasonable?
Voltage Selection: I am confused about which voltage to use for short-circuit calculations:
The transformer nameplate voltage is 22kV/433V.
A previous report I reviewed uses 415V for calculations.
IEC 60038 defines the nominal system voltage as 400V.
Which voltage should be used for short-circuit calculations in IEC 60909-based fault analysis and for arc flash energy calculations?
Attached is my arc flash study report, showing high incident energy values. Would appreciate any guidance on whether my inputs are correct or if I need adjustments.
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