Short Circuit Data: motor_contribution
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 | notes | xr ratio max (dimensionless) | xr ratio typical (dimensionless) |
|---|---|---|---|---|
| motor_contribution | AGGREGATE_LV_LOAD | Aggregate LV motor load (mixed); use 0.25 pu subtransient X on motor kVA | 2.5 | 1 |
| motor_contribution | INDUCTION_LV | Motor subtransient reactance Xd approx 16.7%; contributes 4-6x FLA for 1-4 cycles | 2 | 1.2 |
| motor_contribution | INDUCTION_MV | MV induction motors >250HP; Xd 16.7-20%; higher X/R than LV | 3.5 | 1.5 |
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