Reactive power
Reactive power calculator
Check your reactive-to-active energy ratio against the limits in your country or contract, then estimate the compensation power needed for a target power factor.
Ratio check (enter your own limits)
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The vertical line marks the limit. Above the limit the bar turns red and is labelled "exceeded".
Compensation power
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P: active power, Q: reactive power, S: apparent power. The faint triangle is the current state, the dark one the target. Not to scale.
How is it calculated?
First the reactive-to-active energy ratio is compared with the limits you enter, then the capacitor power for a target power factor is calculated. Results are approximate.
Ratio check (your limits)
ratio = kVArh / kWh; exceeded if ratio > limit
Enter the inductive and capacitive limits that apply to your tariff or grid contract; there are no defaults. A ratio equal to the limit is not counted as exceeded.
Compensation power
Q = P × (tan φ1 − tan φ2), tan φ = √(1 − cos²φ) / cos φ
P: active power (kW), φ1: current and φ2: target power factor angle, Q: required capacitor power (kVAr). A sinusoidal, balanced load is assumed; harmonics are not considered.
Example
- With 10,000 kWh active, 2,500 kVArh inductive and 500 kVArh capacitive energy, the ratios are 25% and 5%; against limits of 20% and 15%, the inductive limit is exceeded.
- At 100 kW active power, raising cos φ from 0.80 to 0.95 needs approximately 42.1 kVAr of compensation.
- Penalty amounts are not calculated.
The example inputs are for illustration only; they are not verified defaults. Results are approximate and do not replace engineering advice.
Frequently asked questions
What is the reactive-to-active energy ratio?
The reactive energy (kVArh) divided by the active energy (kWh) of the same period, calculated separately for inductive and capacitive energy.
Which limits should I enter?
The limits in your tariff or grid contract. This check is country-independent and has no default limits. The Turkish page applies the EPDK limits for Turkey.
How much compensation do I need?
Q = P × (tan φ1 − tan φ2) gives the approximate capacitor power. Step selection and resonance checks must be done separately; results can differ for loads with harmonics.
Does the calculator estimate penalty costs?
No. It shows ratios and whether your limits are exceeded; penalty amounts depend on your tariff and are not calculated.