Minimum Short-Circuit Current Calculator

Calculate AC/DC current in amps from voltage, power (watts/kW), power factor, or resistance. Supports single-phase, three-phase, and Ohm’s Law. Supports: Single-phase and three-phase systems Active power → current Apparent power → current Resistance/impedance → current Bilingual support Key Formulas Single-phase: I = P / (V × cosφ) Three-phase: I = P / (√3 × V × cosφ) Single-phase: I = S / V Three-phase: I = S / (√3 × V) Single-phase: I = V / R Three-phase: I = V / (√3 × Z) Example Three-phase system, 400V, 10kW, PF=0.85 → Current ≈ 17.5 A Typical Equipment Current Reference Equipment Power Voltage Power Factor Estimated Current Household Refrigerator 150 W 230 V 0.95 ≈ 0.69 A LED Lighting (Total Load) 200 W 230 V 0.98 ≈ 0.89 A Electric Kettle 2.2 kW 230 V 1.0 ≈ 9.6 A Air Conditioner (1.5 HP) 1.1 kW 230 V 0.85 ≈ 5.6 A Three-Phase Water Pump 7.5 kW 400 V 0.88 ≈ 12.3 A Industrial Motor (15 kW) 15 kW 400 V 0.9 ≈ 24.1 A Solar Inverter (DC Output) 5 kW 48 V — ≈ 104 A Frequently Asked Questions (FAQ) Can this calculator handle both AC and DC circuits? Yes! It supports DC (using I = P/V or I = V/R) and AC single-phase/three-phase systems (with power factor and impedance). What if I don’t know the power factor? For resistive loads (heaters, incandescent lamps), use PF = 1.0. For motors, a typical value is 0.8–0.9. You can adjust it to see how current changes. Is this suitable for motor full-load current (FLC) estimation? This tool calculates theoretical current using formulas. For NEC-compliant FLC values, refer to standard tables—but this is excellent for preliminary sizing and understanding. Why does three-phase current use √3 in the formula? In balanced three-phase systems, line voltage is √3 times the phase voltage, which reduces the current per conductor for the same power—improving efficiency. Applications Home Electrical Projects: Size breakers, wiring, and outlets based on appliance current draw. Solar & Battery Systems: Calculate DC current for inverters, charge controllers, and battery banks. Industrial Maintenance: Estimate motor or pump operating current before installation. Education & Training: Visualize how voltage, power, and power factor affect current in real time. Energy Audits: Convert equipment nameplate data (kW, V, PF) into actual current for load analysis. Who Should Use This Tool? Electrical engineers and designers Electricians and maintenance technicians Students of physics or electrical engineering DIY homeowners installing EV chargers, solar panels, or workshops Renewable energy professionals

Calculates the neutral current in a three-phase, four-wire system based on phase currents. Supports: Any three-phase current values Real-time neutral current calculation Bilingual support (Chinese/English) Key Formula I_N = √(I_A² + I_B² + I_C² - I_A×I_B - I_B×I_C - I_C×I_A) Where: I_A, I_B, I_C: Phase currents I_N: Neutral current Example Phase A: 10A, Phase B: 10A, Phase C: 5A → Neutral current ≈ 5.0A

Maximum short-circuit current

Calculate the operating current (I b ) of electrical equipment based on active power, voltage, power factor, and coincidence factor—essential for sizing cables, breakers, and protection devices in AC systems. This tool helps engineers, electricians, and designers determine the actual running current under real-world conditions, including multiple loads with varying usage patterns. Supports: Single-phase, two-phase, and three-phase AC systems Standard voltages (e.g., 230V L-N, 400V L-L) Custom voltage input Adjustable power factor (cosφ) Adjustable coincidence factor (F c ) for group load estimation Input via active power (P) or apparent power (S) Key Formulas Single-phase: I b = (F c × P) / (U 0 × cosφ) I b = (F c × S) / U 0 Two-phase: I b = (F c × P) / (U × cosφ) I b = (F c × S) / U Three-phase: I b = (F c × P) / (√3 × U × cosφ) I b = (F c × S) / (√3 × U) Apparent Power: S = √(P² + Q²) Variables: I b : Operating current (A) F c : Coincidence factor (0–1) P: Active power (W) Q: Reactive power (VAr) S: Apparent power (VA) U 0 : Line-to-neutral voltage (V) U: Line-to-line voltage (V) cosφ: Power factor (0.1–1.0) Example Three-phase system, 400 V (L-L), 10 kW, PF = 0.85, F c = 1.0 → Operating current ≈ 19.5 A Frequently Asked Questions (FAQ) What is operating current? Operating current (I b ) is the actual current drawn by equipment during normal operation, adjusted for load diversity using the coincidence factor. Why include coincidence factor? Because not all loads operate at full capacity simultaneously. For example, a factory may have 10 motors, but only 7 run at once → use F c = 0.7 to avoid over-sizing circuits. Can I use this for DC systems? No—this calculator is designed for AC systems only. For DC, use I = P / V (no √3 or power factor). How do I find the power factor if I don’t know it? Use typical values: 0.8–0.9 for motors, 0.95–1.0 for resistive loads (heaters, lighting). You can adjust it to see how current changes. Applications Electrical Design: Size conductors, circuit breakers, and fuses based on actual load demand. Panel Load Calculation: Estimate total current for multiple devices using coincidence factor. Energy Audits: Convert nameplate data into real-world current draw. Renewable Integration: Calculate inverter output current with partial load factors. Educational Use: Teach students about AC power relationships and load diversity. Who Should Use This Tool? Electrical engineers designing LV distribution systems Electricians installing motors, pumps, or HVAC systems Maintenance technicians troubleshooting overloads Facility managers planning upgrades or expansions Students learning AC power fundamentals