This tool calculates the protected area between two lightning rods based on the IEC 62305 standard and the Rolling Sphere Method, suitable for building, tower, and industrial facility lightning protection design. Parameter Description Current Type Select the type of current in the system: - Direct Current (DC): Common in solar PV systems or DC-powered equipment - Alternating Single-Phase (AC Single-Phase): Typical in residential power distribution Note: This parameter is used to distinguish input modes but does not affect the protection zone calculation directly. Inputs Choose input method: - Voltage/Power: Enter voltage and load power - Power/Resistance: Enter power and line resistance Tip: This feature may be used for future extensions (e.g., ground resistance or induced voltage calculation), but it does not influence the geometric protection range. Height of Lightning Rod A The height of the primary lightning rod, in meters (m) or centimeters (cm). Usually the taller rod, defining the upper boundary of the protection zone. Height of Lightning Rod B The height of the second lightning rod, same unit as above. If the rods are of different heights, an unequal-height configuration is formed. Space Between Two Lightning Rods Horizontal distance between the two rods, in meters (m), denoted as (d). General rule: \( d \leq 1.5 \times (h_1 + h_2) \), otherwise effective protection cannot be achieved. Height of the Protected Object The height of the structure or equipment to be protected, in meters (m). This value must not exceed the maximum allowable height within the protection zone. Usage Recommendations Prefer equal-height rods for simpler design Keep spacing less than 1.5 times the sum of rod heights Ensure the protected object's height is below the protection zone For critical facilities, consider adding a third rod or using a meshed air-termination system

Calculate AC and DC current in amps from voltage, power (watts/kW), power factor, or resistance. Supports single-phase, two-phase (2-wire), three-phase, and Ohm’s Law. Ideal for electrical engineers, electricians, students, and DIY projects. Includes motor load estimation Supported Systems & Key Formulas System Type Formula Notes DC I = P / VI = V / R No power factor; pure resistive load Single-Phase AC I = P / (V × cosφ)I = S / V cosφ = power factor; S = apparent power Two-Phase (2-Wire) AC I = P / (V × cosφ) × √2 Important: This mode is specifically designed for two-phase, two-wire systems where the phase difference is 90°. The factor √2 arises because each phase contributes independently, and the total power is distributed across two conductors with orthogonal phase angles. Common in older industrial installations and some specialized motor drives. Three-Phase AC I = P / (√3 × V × cosφ)I = S / (√3 × V) √3 ≈ 1.732; used for balanced three-phase systems Ohm’s Law I = V / RI = V / Z R = resistance (Ω); Z = impedance (Ω) Example Calculation Three-phase system: 400V, 10kW, PF = 0.85 I = 10,000 / (√3 × 400 × 0.85) I ≈ 10,000 / (1.732 × 400 × 0.85) I ≈ 10,000 / 586.4 ≈ 17.0 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 circuits using I = P/V or I = V/R AC single-phase with power factor AC two-phase (2-wire) — specifically designed for 90° phase-shifted systems AC three-phase balanced systems All formulas are dynamically applied based on your selection. What if I don’t know the power factor? Use typical values: Resistive loads (heaters, incandescent lamps): PF = 1.0 Inductive loads (motors, transformers): PF = 0.8–0.9 Capacitive loads (some electronics): PF ≈ 0.95 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

Calculate resistance (Ω) from V, I, P, or Z in DC and AC circuits using Ohm’s Law. Includes power factor handling for real-world accuracy. “Tendency of a body to oppose the passage of an electric current.” This is the fundamental definition of resistance: the property of a material that resists the flow of electric current. Accurately calculating resistance is essential for circuit design, troubleshooting, and energy efficiency analysis—whether in direct current (DC) or alternating current (AC) systems. Who Is This Tool For? Electrical engineers: for load modeling, protection coordination, and pre-simulation parameter estimation. Electricians and field technicians: to quickly verify equipment resistance and diagnose short circuits, ground faults, or insulation degradation. Students and electronics hobbyists: to understand practical applications of Ohm’s Law across different circuit conditions. Energy auditors and efficiency consultants: to evaluate operational efficiency using resistance and power factor relationships. Automation and control engineers: for precise impedance matching in sensor loops or PLC input modules. Typical Use Cases Scenario Application Motor winding inspection Measure voltage and current to back-calculate equivalent resistance and detect inter-turn short circuits. Heating element verification Given rated voltage and power (e.g., 220V / 1500W), compute theoretical resistance to assess aging or failure. Lighting system design Calculate equivalent resistance of LED drivers or incandescent loads to ensure voltage drop stays within limits. UPS and inverter testing In single-phase AC output, combine apparent power and power factor to isolate the resistive component of the load. Educational labs Help students visualize why V/I ≠ R in AC circuits due to reactance and phase shift. Calculation Principle The calculator is based on Ohm's Law and its derived forms. Resistance (R) can be computed using any of the following equivalent formulas: R = V / I R = P / (I^2) R = (V^2) / P R = Z / Power Factor Where: R: Resistance (Ω) V: Voltage (V) I: Current (A) P: Power (W) Z: Impedance (Ω) Power Factor: Ratio of active power to apparent power, ranging from 0 to 1 Note: In AC circuits, these formulas are only fully equivalent when the power factor equals 1 (purely resistive load). Parameter Details Current Type Direct Current (DC): Current flows steadily in one direction from positive to negative pole. Frequency is zero. In this case, impedance Z equals resistance R, and power factor is always 1. Alternating Current (AC): Current direction and amplitude vary periodically at a constant frequency. Single-phase system: Two conductors — one phase and one neutral (zero potential). Two-phase system: Two phase conductors; neutral may be present in three-wire configurations. Three-phase system: Three phase conductors; neutral is included in four-wire systems. This calculator currently supports DC and single-phase AC inputs. For three-phase systems, convert line-to-line voltage to phase voltage first: V_phase = V_line / sqrt(3), then treat as single-phase. Voltage Voltage is the difference in electric potential between two points. Input method depends on system type: Single-phase: Enter Phase-Neutral voltage. Two-phase / Three-phase: Enter Phase-Phase voltage. Example: A standard 220V household outlet is single-phase → input 220V. An industrial 380V supply is three-phase → for per-phase calculation, use 380 / sqrt(3) ≈ 220V. Current Current is the flow of electric charge through a conductor, measured in amperes (A). It is one of the most direct inputs for resistance calculation via R = V / I. Power Electric power is the rate at which energy is supplied or consumed by a component, measured in watts (W). In AC systems, distinguish between: Active Power (W): Real power that performs useful work. Reactive Power (VAR): Power used to establish magnetic/electric fields; does no real work. Apparent Power (VA): Vector sum of active and reactive power: S = sqrt(P^2 + Q^2). Important: The "P" in the formulas above refers to active power (W). If you input apparent power (VA), you must also provide the power factor; otherwise, results will be inaccurate. Power Factor Power Factor = cos(phi), where phi is the phase angle between voltage and current. Pure resistive load (e.g., heater, incandescent lamp): Power Factor = 1 Inductive or capacitive loads (e.g., motors, transformers): Power Factor < 1 (typically 0.7–0.95) In AC circuits, resistance is derived from impedance and power factor: R = Z * Power Factor = Z / (1 / Power Factor) Impedance Impedance (Z) is the total opposition to alternating current flow, combining resistance (R) and reactance (X), measured in ohms (Ω). The relationship is: Z = sqrt(R^2 + X^2) Therefore, resistance can only be extracted from impedance if the power factor (or phase angle) is known. People Also Ask (FAQ) Why can’t I use R = V / I directly in AC circuits? Because V / I gives you impedance (Z), not pure resistance (R). To get R, multiply by the power factor: R = (V / I) * cos(phi). Do I need to enter power factor for DC circuits? No. In DC, there is no phase shift, so power factor is always 1, and Z = R. Can I calculate resistance if I only know reactive power (VAR)? No. Resistance relates only to active power. You need either active power (W), or apparent power (VA) plus power factor. Can this tool be used for three-phase motors? Yes, but treat it per phase. Measure phase voltage and phase current, or convert line values using V_phase = V_line / sqrt(3), then apply single-phase formulas. Usage Tips Prefer voltage + current input: Most accurate and least prone to error. Ensure unit consistency: V in volts, I in amps, P in watts. Always enter power factor for AC: If omitted, the calculator assumes cos(phi) = 1, which overestimates resistance. Validate results: Example – a 1000W heater at 220V should have R ≈ (220^2)/1000 = 48.4 Ω. Large deviations suggest input errors. This tool adheres to international electrical standards (IEC 60050) and is suitable for education, engineering design, and field maintenance—helping users quickly and accurately determine the effective resistance in real-world circuits.

Free online calculator for active (real) power in DC and AC circuits. Supports voltage, current, resistance, impedance, power factor, or apparent/reactive power inputs. Active power, also known as real power, is the portion of electrical power that performs useful work in a circuit—such as producing heat, light, or mechanical motion. Measured in watts (W) or kilowatts (kW), active power represents the actual energy consumed by a load and is the basis for electricity billing. This tool calculates active power based on voltage, current, power factor, apparent power, reactive power, resistance, or impedance. It supports both single-phase and three-phase systems, making it ideal for motors, lighting, transformers, and industrial equipment. Parameter Description Parameter Description Current Type Select circuit type: • Direct Current (DC): Constant flow from positive to negative pole • Single-phase AC: One live conductor (phase) + neutral • Two-phase AC: Two phase conductors, optionally with neutral • Three-phase AC: Three phase conductors; four-wire system includes neutral Voltage Electric potential difference between two points. • Single-phase: Enter Phase-Neutral voltage • Two-phase / Three-phase: Enter Phase-Phase voltage Current Flow of electric charge through a material, unit: Amperes (A) Power Factor Ratio of active power to apparent power, indicating efficiency. Value between 0 and 1. Ideal value: 1.0 Apparent Power Product of RMS voltage and current, representing total power supplied. Unit: Volt-Ampere (VA) Reactive Power Energy alternately flowing in inductive/capacitive components without conversion to other forms. Unit: VAR (Volt-Ampere Reactive) Resistance Opposition to DC current flow, unit: Ohm (Ω) Impedance Total opposition to AC current, including resistance, inductance, and capacitance. Unit: Ohm (Ω) Calculation Principle The general formula for active power is: P = V × I × cosφ Where: P: Active power (W) V: Voltage (V) I: Current (A) cosφ: Power factor Other common formulas: P = S × cosφ P = Q / tanφ P = I² × R P = V² / R Example Calculation If voltage is 230V, current is 10A, and power factor is 0.8, then active power is: P = 230 × 10 × 0.8 = 1840 W Usage Recommendations Monitor active power regularly to assess equipment efficiency Use data from energy meters to analyze consumption patterns and optimize usage Consider harmonic distortion when dealing with nonlinear loads (e.g., VFDs, LED drivers) Active power is the basis for electricity billing, especially under time-of-use pricing schemes Combine with power factor correction to improve overall energy efficiency Common Input Combinations The calculator supports multiple input methods depending on available measurements: Voltage/Resistance: Use when current is not directly measurable Voltage/Impedance: For AC circuits with known Z and cosφ Current/Resistance: Direct calculation via P = I² × R Current/Impedance: Requires power factor to extract resistive component Voltage/Current: Most direct method, requires power factor for AC Apparent power/Reactive power: Use trigonometric relationship to find active power Apparent power: Only valid if power factor is known Reactive power: Must be combined with power factor or apparent power Supported Circuit Types Direct Current (DC): No phase shift, power factor = 1, impedance = resistance Single-phase AC: Common in homes and small commercial buildings Two-phase AC: Less common, used in specific industrial applications Three-phase AC: Standard for motors, transformers, and industrial power systems People Also Ask (FAQ) What is the difference between active power and apparent power? Active power (P) is the real power doing useful work (in watts). Apparent power (S) is the vector sum of active and reactive power (in VA). The ratio P/S is the power factor. Why is active power important for electricity billing? Utilities charge based on active power because it represents the actual energy consumed. Reactive power increases current but does no useful work, so it’s not billed directly. Can I calculate active power without knowing the power factor? Only if you know the resistance (for DC or purely resistive AC loads). Otherwise, you need either power factor or a combination of apparent/reactive power. How does this tool handle three-phase systems? For three-phase systems, enter line-to-line voltage and per-phase values. The tool assumes balanced loads and applies the standard three-phase formula: P = √3 × V_line × I_line × cosφ. Is this calculator suitable for non-linear loads like LED drivers? Yes, but keep in mind that non-linear loads may have distorted waveforms and lower power factors. Use measured RMS values and actual power factor for best accuracy. Calculation Example Given: Current type: Direct Current Voltage: 220 V Resistance: 20 Ω Using the formula: P = V² / R P = 220² / 20 = 48400 / 20 = 2420 W = 2.42 kW Result: Active power = 2.42 kW This matches the example shown in the interface screenshot. This tool adheres to international electrical standards (IEC 60050) and is suitable for engineers, technicians, students, and facility managers who need to calculate real power in various electrical systems.

Calculate power factor (PF) in AC circuits using voltage, current, active power, reactive power, resistance, or impedance. Supports single-phase, two-phase, and three-phase systems. Based on IEC standards for electrical efficiency analysis. Input Parameter Symbol Unit Required Combinations Voltage V V (volts) With current → S = V×I Current I A (amperes) With voltage → S = V×I Active Power P W (watts) With S or Q → PF = P/S or P/√(P²+Q²) Reactive Power Q VAR With P → PF = P / √(P² + Q²) Resistance R Ω (ohms) With Z → PF = R / Z Impedance Z Ω (ohms) With R → PF = R / Z Definition and Importance Power factor (PF) is the ratio of active power (P) to apparent power (S): PF = P / S = cosφ PF = 1.0: Purely resistive load (e.g., heater), no reactive power PF < 1.0: Inductive or capacitive load (e.g., motors, transformers) Low PF consequences: Increased line current Higher copper losses Reduced transformer capacity Utility penalties (common if PF < 0.85–0.90) Calculation Methods The calculator uses one of the following equivalent formulas based on available inputs: From P and S: PF = P / (V × I) From P and Q: PF = P / √(P² + Q²) From R and Z: PF = R / Z From phase angle φ: PF = cosφ (if angle is known) Note: DC circuits are not supported — power factor is always 1.0 in DC systems. System Support Single-phase AC Enter Phase-Neutral voltage and per-phase current. Two-phase AC Enter Phase-Phase voltage; assumes balanced load. Three-phase AC Enter Line-to-Line voltage (V LL) and line current (I L). The calculator assumes a balanced system and computes total apparent power as S = √3 × V LL × I L. Typical Applications Industrial motor systems: Verify PF before installing capacitor banks Energy audits: Identify low-efficiency loads for correction Electrical design: Size conductors and protection devices with accurate current estimates Utility compliance: Ensure PF ≥ 0.95 to avoid demand charges Educational labs: Demonstrate relationship between P, Q, S, and PF Usage Guidelines Use RMS values for voltage and current in AC systems For non-linear loads (e.g., VFDs, LED drivers), measured PF may include harmonic distortion effects If only apparent power (VA) is known, active power (W) must also be provided Resistance and impedance inputs assume linear, sinusoidal conditions Frequently Asked Questions (FAQ) What is the power factor and why is it important? The power factor (PF) is the ratio of active power to apparent power in AC circuits, indicating how effectively electrical energy is being used. A high PF means less wasted energy and more efficient use of electrical infrastructure. How do I calculate power factor if I only know voltage and current? To calculate power factor using just voltage and current, you need to measure or estimate the phase angle between them. The formula is: PF = cosφ, where φ is the phase angle. Alternatively, if you can also measure active power (P), then PF = P / (V × I). Can this calculator be used for DC systems? No, power factor is a concept applicable only to AC systems. In DC systems, the power factor is always 1 because there is no phase shift between voltage and current. What does a low power factor indicate about my system? A low power factor indicates that your system has significant reactive power, which means some of the electrical energy is being stored and then released by inductive or capacitive loads without doing useful work. This results in higher currents, increased losses, and possibly utility penalties. How can I improve the power factor in my facility? Improving power factor often involves adding capacitor banks to compensate for reactive power, especially in industrial settings with many motors. Reducing the number of lightly loaded inductive devices and ensuring proper maintenance of existing equipment can also help. Is this tool suitable for three-phase systems? Yes, this calculator supports single-phase, two-phase, and three-phase systems. For three-phase calculations, enter line-to-line voltage and per-phase current values. Ensure balanced load conditions for accurate results. Why might utilities charge extra fees for low power factors? Utilities may impose penalties on customers with low power factors because they require larger capacity infrastructure to deliver the same amount of active power. Low PF increases transmission losses and reduces grid efficiency. This calculator adheres to IEC 60050 terminology and is intended for use by electrical engineers, facility managers, technicians, and students in power systems analysis.

Free online reactive power calculator for AC systems.Calculate reactive power (Q) in VAR for AC systems using voltage, current, active power, apparent power, or power factor. Supports single-phase and three-phase configurations for power quality analysis, capacitor bank design, and energy efficiency optimization. Reactive power is the energy alternately flowing in inductive and capacitive components of an AC circuit without being transformed into other forms of energy. Although it does not perform useful work, reactive power is essential for maintaining voltage stability and system performance. Unit: Volt-Ampere Reactive (VAR). What Is Reactive Power and Why Is It Important? Reactive power (Q) sustains the electric and magnetic fields in motors, transformers, and other inductive loads. Without it, AC systems would collapse due to insufficient voltage support—even though it doesn’t directly consume energy. How Do You Calculate Reactive Power? Reactive power can be calculated using any of these formulas: Q = V × I × sinφ Q = √(S² − P²) Q = P × tanφ Where: V = Voltage (V), I = Current (A), φ = phase angle, P = Active power (W), S = Apparent power (VA) What Is the Unit of Reactive Power? The unit is Volt-Ampere Reactive (VAR). Larger systems use kVAR (kilovar) or MVAR (megavar). Does Reactive Power Consume Energy? No. Reactive power oscillates between source and load without net energy consumption. However, it increases current flow, causing higher losses and voltage drops in distribution lines. Can Reactive Power Be Negative? Yes. By convention: • Inductive loads (motors, transformers): Q > 0 (absorb VAR) • Capacitive loads (capacitor banks, cables): Q < 0 (supply VAR) How Does Reactive Power Affect Power Factor? Power factor (PF) = P / S = cosφ. Higher reactive power reduces PF, leading to inefficient power usage. Utilities often penalize low PF in industrial billing. Why Is Reactive Power Needed in AC Systems? It enables electromagnetic devices to function by establishing magnetic fields. Without reactive power, motors wouldn’t start, and transformers couldn’t transfer energy. How to Reduce Reactive Power in Industrial Systems? Use power factor correction via capacitor banks or synchronous condensers. This offsets inductive VAR with capacitive VAR, bringing PF closer to 1.0 and reducing line losses. Parameter Description Parameter Description Current Type Select the type of current: • Direct Current (DC): Constant flow; no reactive power • Alternating Current (AC): Reverses direction periodically System configurations: – Single-phase: Phase + neutral – Two-phase: Two phases (± neutral) – Three-phase: Three phases (± neutral) Voltage Electric potential difference. • Single-phase: Enter Phase-Neutral voltage • Two/Three-phase: Enter Phase-Phase voltage Current Flow of charge, measured in amperes (A) Active Power Useful power consumed (W). Formula: P = V × I × cosφ Apparent Power Total power supplied (VA). Formula: S = V × I Power Factor PF = P / S = cosφ. Ranges from 0 to 1. Resistance Opposition to DC current. R = ρ × l / A (Ω) Impedance Total AC opposition: Z = √(R² + (XL − XC)²) (Ω) Reactive Power Calculation Principle Reactive power \( Q \) is calculated as: Q = V × I × sinφ or Q = √(S² − P²) If the circuit is inductive, Q > 0 (absorbs reactive power); if capacitive, Q < 0 (supplies reactive power). Usage Recommendations Low power factor increases line losses and voltage drop in power systems Capacitor banks are commonly used in industrial plants to compensate reactive power Use this tool to calculate reactive power from known voltage, current, and power factor values Monitor Q to optimize transformer loading and avoid utility penalties Who Should Use This Tool? Electrical engineers: for load flow studies and PF correction design Plant maintenance teams: to audit motor efficiency and capacitor bank performance Students: to visualize the relationship between P, Q, and S in power triangles Energy consultants: to recommend cost-saving reactive power compensation strategies This calculator adheres to IEC 60050 standards and supports accurate reactive power analysis in real-world AC power systems.

Calculate impedance (Ω) in AC circuits using voltage, current, power, or resistance. Supports single, two, and three-phase systems for electrical engineering and power analysis. Impedance is the total opposition of a circuit to the flow of alternating electric current, measured in ohms (Ω). It includes resistance, inductive reactance, and capacitive reactance. Impedance is a key parameter in AC circuit analysis and affects voltage drop, current flow, and protection coordination. What Is Impedance and How Is It Different from Resistance? Resistance opposes DC current and is due to material properties. Impedance opposes AC current and includes resistance plus reactive components (inductive and capacitive). In DC, impedance equals resistance; in AC, they differ. How Do You Calculate Impedance in an AC Circuit? Use one of these formulas: Z = V / I Z = √(R² + (XL − XC)²) Z = S / (V × I) → when apparent power is known Where: Z = Impedance (Ω), V = Voltage (V), I = Current (A) R = Resistance (Ω), XL = Inductive reactance, XC = Capacitive reactance Parameter Description Parameter Description Current Type Select the type of current: • Direct Current (DC): Constant flow; impedance = resistance • Alternating Current (AC): Reverses direction periodically System configurations: – Single-phase: Phase + neutral – Two-phase: Two phases (± neutral) – Three-phase: Three phases (± neutral) Voltage Electric potential difference. • Single-phase: Enter Phase-Neutral voltage • Two/Three-phase: Enter Phase-Phase voltage Current Flow of charge, measured in amperes (A) Active Power Useful power consumed (W). Formula: P = V × I × cosφ Reactive Power Energy oscillation in inductors/capacitors (VAR). Formula: Q = V × I × sinφ Apparent Power Total power supplied (VA). Formula: S = V × I Power Factor PF = P / S = cosφ. Ranges from 0 to 1. Resistance Opposition to DC current. R = ρ × l / A (Ω) Impedance Calculation Principle Impedance \( Z \) is defined as: Z = V / I For a series RLC circuit: Z = √(R² + (XL − XC)²) If XL > XC, the circuit is inductive; if XC > XL, it is capacitive. What Is the Unit of Impedance? The unit is ohm (Ω), same as resistance. Larger values may be expressed in kΩ or MΩ. Can Impedance Be Negative? No. Impedance is always a positive value because it represents magnitude of opposition. However, phase angle can be negative if the circuit is capacitive. How Does Impedance Affect AC Circuits? Impedance determines the amount of current flowing for a given voltage. High impedance reduces current, while low impedance increases it. It also affects power factor, voltage regulation, and fault current levels. What Is the Formula for Total Impedance in a Series RLC Circuit? In a series RLC circuit: Z = √(R² + (XL − XC)²) Where: XL = 2πfL XC = 1/(2πfC) f = Frequency (Hz), L = Inductance (H), C = Capacitance (F) Why Is Impedance Important in Power Systems? Impedance affects short-circuit current magnitude, voltage drop under load, transformer loading, and protective device settings. Accurate impedance values are essential for system design, relay coordination, and stability studies. Usage Recommendations Impedance affects short-circuit current, voltage drop, and protection device selection Low power factor increases line losses; consider reactive power compensation Use this tool to back-calculate unknown impedance values from measured voltage and current Verify impedance values during commissioning and maintenance to ensure system reliability This calculator adheres to IEC 60050 standards and supports accurate impedance analysis in real-world AC power systems.

Calculate neutral current in 3-phase systems with unbalanced loads using phase A, B, C currents. No harmonics assumed. Compliant with NEC 220.61 & IEC 60364. Calculate the neutral current in a three-phase, four-wire system based on unbalanced phase currents. This tool uses vector summation principles for linear loads only, assuming no harmonic distortion. When You Need This Calculation Determining whether your neutral conductor is properly sized for mixed single-phase loads Verifying compliance with NEC Article 220.61 or IEC 60364-5-52 for neutral load calculation Preventing overheating due to excessive neutral current in panelboards Designing feeders for commercial buildings with unbalanced lighting and receptacle loads Performing preliminary load analysis during electrical inspections Underlying Principle The neutral current is calculated using the following formula: IN = √(IA2 + IB2 + IC2 - IA×IB - IB×IC - IC×IA) Where: IA, IB, IC: Phase currents in amperes (A) IN: Resultant neutral current (A) Note: This formula applies to sinusoidal, linear loads with 120° phase separation. It does not account for harmonic currents, which can significantly increase neutral current. Practical Example Scenario: A commercial building has the following phase currents: Phase A: 10 A Phase B: 5 A Phase C: 2 A Calculation: I_N = √(10² + 5² + 2² - 10×5 - 5×2 - 2×10) = √(100 + 25 + 4 - 50 - 10 - 20) = √(59) ≈ 7.68 A → Rounded to 7.7 A This means the neutral conductor must carry ~7.7 A continuously. If not sized correctly, it may overheat or trip protective devices. Key Limitations & Assumptions No harmonics: Assumes purely resistive/reactive loads (e.g., motors, heaters). Does not model triplen harmonics from VFDs, computers, or LED drivers. Linear loads only: Not suitable for non-linear loads where current waveforms are distorted. Phase angle assumption: Assumes standard 120° phase difference between A-B-C. Not valid for unbalanced systems with phase shifts. Single frequency: Only applicable to 50/60 Hz AC systems. Not for DC: This is an AC phasor sum; does not apply to DC systems. Use Cases by Industry Industry Application Commercial Buildings Panelboard neutral sizing for lighting and outlets Industrial Facilities Feeder design for mixed motor and control loads Data Centers Assessing neutral current in UPS distribution Residential Verifying service entrance neutral capacity Education Teaching three-phase system behavior For Professionals Who design or inspect electrical systems per NEC or IEC 60364 size neutral conductors to prevent overheating troubleshoot neutral-related faults in panelboards perform load calculations for new construction or retrofits teach power system fundamentals to students Compliance Context NEC Article 220.61: Requires neutral load calculation based on unbalanced current IEC 60364-5-52: Specifies rules for final circuit and socket-outlet installations IEEE 141: Recommends practices for electric power distribution UL 486A/B: Wiring device standards including neutral handling Frequently Asked Questions How do you calculate neutral current in a 3-phase system? For unbalanced linear loads without harmonics, use: I_N = √(I_A² + I_B² + I_C² - I_A×I_B - I_B×I_C - I_C×I_A). This accounts for phase angles and vector addition. In balanced systems, I_N = 0. Why is neutral current important? Neutral current carries the imbalance between phases. If too high, it can overheat conductors, trip breakers, or cause voltage drop—especially in lighting or IT systems where loads are often unbalanced. What happens if neutral is not connected? Without a neutral connection, phase voltages become unbalanced, potentially causing equipment damage or malfunction. The neutral ensures stable voltage across single-phase loads. Does this calculator include harmonic effects? No. This tool assumes linear loads with no harmonics. For non-linear loads (e.g., VFDs, LED drivers), triplen harmonics (3rd, 9th, etc.) add in phase on the neutral—can cause up to 1.7× total load.

Calculate apparent power (VA) in AC/DC circuits using voltage, current, power factor, resistance, or impedance. Supports single, two, and three-phase systems for electrical engineering. Apparent power is the vector sum of active and reactive power, representing total power supplied by the source. It is measured in Volt-Ampere (VA) and is crucial for sizing transformers, generators, and circuit breakers. What Is Apparent Power and How Is It Calculated? Apparent power (S) is the total power flowing in a circuit, regardless of whether it performs useful work. It is calculated as: S = √(P² + Q²) S = V × I (single-phase) S = √3 × V × I (three-phase) Where: P = Active power (W), Q = Reactive power (VAR) V = Voltage (V), I = Current (A) What Is the Unit of Apparent Power? The unit is Volt-Ampere (VA). Larger systems use kVA (kilovolt-ampere) or MVA (megavolt-ampere). How Do You Calculate Apparent Power in a Three-Phase System? In a three-phase system: S = √3 × VL-L × IL Where: VL-L = Line-to-line voltage IL = Line current Note: This assumes balanced loads. For unbalanced systems, sum individual phase powers. Is Apparent Power the Same as Real Power? No. Real (active) power (P) is the power that performs useful work (e.g., heat, motion). Apparent power (S) includes both real and reactive components. They are equal only when power factor = 1. What Is the Relationship Between Apparent, Active, and Reactive Power? They form a right triangle known as the **power triangle**: Active power (P) = S × cosφ Reactive power (Q) = S × sinφ Apparent power (S) = √(P² + Q²) Where φ is the phase angle between voltage and current. Why Is Apparent Power Important in Electrical Systems? Apparent power determines the capacity of electrical equipment like transformers, cables, and switchgear. Utilities use it to bill commercial/industrial customers and assess system loading. Parameter Description Parameter Description Current Type Select the type of current: • Direct Current (DC): Constant flow; S = V × I • Alternating Current (AC): Reverses direction periodically System configurations: – Single-phase: Phase + neutral – Two-phase: Two phases (± neutral) – Three-phase: Three phases (± neutral) Voltage Electric potential difference. • Single-phase: Enter Phase-Neutral voltage • Two/Three-phase: Enter Phase-Phase voltage Current Flow of charge, measured in amperes (A) Active Power Useful power consumed (W). Formula: P = V × I × cosφ Reactive Power Energy oscillation in inductors/capacitors (VAR). Formula: Q = V × I × sinφ Power Factor PF = P / S = cosφ. Ranges from 0 to 1. Resistance Opposition to DC current. R = ρ × l / A (Ω) Impedance Total AC opposition: Z = √(R² + (XL − XC)²) (Ω) Apparent Power Calculation Principle Apparent power \( S \) is defined as: S = √(P² + Q²) Alternatively: S = V × I (single-phase) S = √3 × V × I (three-phase) S = V² / R (for DC or purely resistive AC) S = I² × Z Usage Recommendations Use this tool to size transformers, generators, and UPS systems Monitor apparent power to prevent overloading equipment Enter any two known values (e.g., V & I, P & PF) to compute missing parameters For three-phase systems, ensure line-to-line voltage is used This calculator adheres to IEC 60050 standards and supports accurate apparent power analysis in real-world electrical systems.

Calculate motor current (amps) from kW or HP, voltage, power factor & efficiency. Supports DC, single-phase & 3-phase AC motors. Free online tool for engineers & electricians. How to Use This Calculator Enter your motor’s power (kW or HP), voltage (V), power factor (PF), and efficiency (η). The tool automatically computes the current (amps) for: Direct Current (DC) motors Single-phase AC motors Three-phase AC motors (most common in industrial applications) Common Applications This calculator helps professionals with real-world tasks such as: Sizing circuit breakers and fuses – Ensure protection devices match motor current draw. Selecting wire gauge – Prevent overheating by choosing correct cable size. Verifying nameplate data – Cross-check manufacturer specs during maintenance. Designing motor control panels – Accurately specify contactors, overload relays, and starters. Energy audits – Estimate operating current for efficiency analysis. Key Formulas The calculator uses industry-standard formulas based on IEC and NEC guidelines: DC Motor: I = P ÷ (V × η) Single-Phase AC: I = P ÷ (V × PF × η) Three-Phase AC: I = P ÷ (√3 × V × PF × η) Note: Power (P) must be in watts (W). If using horsepower (HP), it is automatically converted to watts (1 HP = 746 W). Frequently Asked Questions (FAQ) How many amps does a 10 HP motor draw? It depends on voltage and phase. For example, a 10 HP (7.46 kW), 480V three-phase motor with PF=0.85 and η=0.9 draws about 11.8 amps. What is full load current (FLC)? Full load current is the maximum current a motor draws when operating at rated power and voltage. It’s used to size protective devices per NEC Table 430.250. Why do I need power factor and efficiency? Because motors don’t convert 100% of electrical input into mechanical output. Ignoring PF and η leads to underestimating current—potentially causing tripped breakers or fire hazards. Can I use this for generator sizing? Yes! Calculate motor starting and running current to ensure your generator can handle the load without voltage drop. Does this work for variable frequency drives (VFDs)? This calculator gives fundamental frequency current. VFDs introduce harmonics, so actual current may differ. Use for initial estimates only.