UPS बैटरी साइज़िंग कैलकुलेटर
UPS सिस्टम के लिए उचित बैटरी क्षमता निकालें।
277 V for 480Y/277, 120 V for 208Y/120
Total impedance of fault path
Ground Fault Current
461.7 A
Ground Fault Current vs System Voltage (Phase-to-Ground)
सूत्र
## Ground Fault Current Estimation Ground fault current flows when a live conductor contacts grounded metal. Its magnitude determines how quickly protection devices clear the fault. ### Formula **I_gf = V_phase / (Z_ground + Z_source)** **Touch Voltage = V_phase x Z_ground / (Z_ground + Z_source)** Low ground-path impedance ensures high fault current, which trips protective devices quickly. High impedance (poor grounding) results in low fault current that may not trip the breaker, leaving a dangerous condition.
हल किया गया उदाहरण
277 V phase-to-ground, 0.5 ohm ground path, 0.1 ohm source impedance.
- 01Ground fault current: 277 / (0.5 + 0.1) = 461.7 A
- 02Fault power: 277^2 / 0.6 = 127,882 W
- 03Touch voltage: 277 x 0.5 / 0.6 = 230.8 V (dangerous)
अक्सर पूछे जाने वाले प्रश्न
What is a safe touch voltage?
Below 50 V is generally safe for dry conditions (IEC 60479). Above this, ground fault protection must clear quickly (within milliseconds).
Why maintain low ground impedance?
Low impedance ensures high fault current, which trips breakers or GFCIs quickly. High impedance may prevent tripping, leaving a shock hazard.
What is GFCI/RCD protection?
Ground Fault Circuit Interrupters detect imbalance between line and neutral (indicating ground fault) and trip at 5-30 mA to protect people.
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