Q = U₀ * I * sinφ
Q = P * tanφ
Q = S * sinφ
Q = √(S² - P²)
Q = I² * Z * sinφ
Q = (I² * R * sinφ) / cosφ
Q = (U₀² * sinφ) / Z
Q = (U₀² * sinφ * cosφ) / R
Q = U * I * sinφ
Q = P * tanφ
Q = S * sinφ
Q = √(S² - P²)
Q = I² * Z * sinφ
Q = (I² * R * sinφ) / cosφ
Q = (U² * sinφ) / Z
Q = (U² * sinφ * cosφ) / R
Q = √3 * U * I * sinφ
Q = P * tanφ
Q = S * sinφ
Q = √(S² - P²)
Q = √3 * I² * Z * sinφ
Q = (√3 * I² * R * sinφ) / cosφ
Q = (√3 * U² * sinφ) / Z
Q = (√3 * U² * sinφ * cosφ) / R
Q = Reactive power (VAr)
S = Apparent power (VA)
P = Active power (W)
I = Current (A)
U₀ = Voltage [L - N] (V)
U = Voltage [L - L] (V)
R = Resistance (Ω)
Z = Impedance (Ω)
cosφ = Power factor
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, it is essential for maintaining voltage stability and system performance. Unit: Volt-Ampere Reactive (VAR).
Select the type of current:
Direct Current (DC): Constant flow from positive to negative pole; no reactive power
Alternating Current (AC): Reverses direction and amplitude periodically at constant frequency
System configurations:
Single-phase: Two conductors (phase + neutral)
Two-phase: Two phase conductors; neutral may be distributed
Three-phase: Three phase conductors; four-wire system includes neutral
Note: Reactive power only exists in AC circuits.
Electric potential difference between two points.
For single-phase: Enter Phase-Neutral voltage
For two-phase or three-phase: Enter Phase-Phase voltage
Flow of electric charge through a material, measured in amperes (A).
Active Power
The power actually consumed by a load and converted into useful energy (e.g., heat, motion).
Unit: Watts (W)
P = V × I × cosφ
Apparent Power
The product of RMS voltage and current, representing total power supplied by the source.
Unit: Volt-Ampere (VA)
Formula:
S = V × I
Power Factor
Ratio of active power to apparent power, indicating efficiency of power usage.
Formula:
PF = P / S = cosφ
where φ is the phase angle between voltage and current. Value ranges from 0 to 1.
Resistance
Opposition to current flow due to material properties, length, and cross-sectional area.
Unit: Ohm (Ω)
Formula:
R = ρ × l / A
Impedance
Total opposition of a circuit to alternating current, including resistance, inductive reactance, and capacitive reactance.
Unit: Ohm (Ω)
Formula:
Z = √(R² + (XL - XC)²)
Reactive power \( Q \) is calculated as:
Q = V × I × sinφ
or:
Q = √(S² - P²)
Where:
S: Apparent power (VA)
P: Active power (W)
φ: Phase angle between voltage and current
If the circuit is inductive, Q > 0 (absorbs reactive power); if capacitive, Q < 0 (supplies reactive power).
1. Low power factor increases line losses and voltage drop in power systems
2. Capacitor banks are commonly used in industrial plants to compensate reactive power
3. Use this tool to calculate reactive power from known voltage, current, and power factor values
Positive Q indicates inductive loads absorbing reactive power. Negative Q indicates capacitive loads supplying reactive power.
In power‑factor‑correction projects, capacitors generate negative reactive power to offset positive inductive reactive power from motors and transformers.
Enter line‑to‑line voltage under three‑phase mode. Enter phase‑neutral voltage under single‑phase mode.
Wrong voltage type will produce incorrect reactive‑power results. Reactive power equals zero for DC mode.
This tool works on ideal sine‑wave assumptions and outputs theoretical reactive‑power values only. Harmonic distortion and line losses are not considered.
For real‑world compensation design, use on‑site power‑quality‑analyzer readings and prevent over‑compensation.
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