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Short Circuit Data: transformer
300KVA to 75KVA
Typical equipment impedances (%Z) and X/R ratios for short circuit calculations per IEEE 141 (Red Book) and IEEE 551 (Violet Book). Covers transformers by kVA, utility sources by voltage level, cables, motor contributions, generators, and reactors.
| equipment type | rating label | asym multiplier typical (dimensionless) | impedance pct max (%) | impedance pct min (%) | impedance pct typical (%) | mva base (MVA) | standard | xr ratio max (dimensionless) | xr ratio min (dimensionless) | xr ratio typical (dimensionless) |
|---|---|---|---|---|---|---|---|---|---|---|
| transformer | 300KVA | 1.19 | 5.75 | 2 | 4.5 | 0.3 | IEEE 551-2006 Table 9-1; ANSI C57.12.01 | 6 | 3 | 5 |
| transformer | 30KVA | 1.12 | 5 | 1.5 | 2.5 | 0.03 | IEEE 551-2006 Table 9-1; ANSI C57.12.01 | 3.5 | 2 | 2.5 |
| transformer | 45KVA | 1.12 | 5 | 1.5 | 2.5 | 0.045 | IEEE 551-2006 Table 9-1; ANSI C57.12.01 | 3.5 | 2 | 2.5 |
| transformer | 5000KVA | 1.3 | 7.5 | 5.5 | 6 | 5 | IEEE 551-2006 Table 9-1; ANSI C57.12.00 | 20 | 12 | 15 |
| transformer | 500KVA | 1.21 | 5.75 | 3.5 | 5.75 | 0.5 | IEEE 551-2006 Table 9-1; ANSI C57.12.01 | 8 | 4 | 6 |
| transformer | 750KVA | 1.22 | 5.75 | 4 | 5.75 | 0.75 | IEEE 551-2006 Table 9-1; ANSI C57.12.01 | 9 | 5 | 6 |
| transformer | 75KVA | 1.14 | 5.75 | 1.5 | 3.1 | 0.075 | IEEE 551-2006 Table 9-1; ANSI C57.12.01 | 4 | 2.5 | 3 |
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