सर्ज प्रोटेक्शन कैलकुलेटर — सूत्र
## Estimating Short Circuit Current
The maximum short-circuit current at a transformer secondary determines the required interrupting capacity of protective devices.
### Formula
**I_sc = I_fla / (Z% / 100)**
Where I_fla is the transformer full-load secondary current and Z% is the transformer impedance.
**I_fla (3-phase) = kVA x 1000 / (sqrt(3) x V_secondary)**
This gives the maximum available fault current at the transformer terminals. Downstream cable impedance reduces the fault current at the load.
The maximum short-circuit current at a transformer secondary determines the required interrupting capacity of protective devices.
### Formula
**I_sc = I_fla / (Z% / 100)**
Where I_fla is the transformer full-load secondary current and Z% is the transformer impedance.
**I_fla (3-phase) = kVA x 1000 / (sqrt(3) x V_secondary)**
This gives the maximum available fault current at the transformer terminals. Downstream cable impedance reduces the fault current at the load.
हल किया गया उदाहरण
500 kVA transformer, 5% impedance, 480 V secondary.
- FLA: 500,000 / (1.732 x 480) = 601.4 A
- I_sc: 601.4 / 0.05 = 12,029 A = 12.0 kA
- Available SC kVA: 500 / 0.05 = 10,000 kVA