Electrical Resistance Calculator (DC and AC)

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

Calculation of voltage

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.