Capacitor kvar required
42.1 kVAR
100 kW × (tan 0.750 − tan 0.329).
IEEE Std 141 · NEMA MG 1
Calculator 17 / IEEE Std 141
Power factor correction
Find the capacitor kvar needed to bring a load from its present power factor to a target power factor, with the before/after current impact.
Load and correction inputs
kVAR = kW × (tan(cos⁻¹ PF₁) − tan(cos⁻¹ PF₂)). Capacitor ratings shown are typical catalog sizes — confirm availability with the vendor. Capacitor installation per NEC Article 460.
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VoltForgePower Factor Correction Report
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Inputs
| Inputs | 100 kW, PF 0.8 → 0.95, three-phase 480 V |
Results
Recommended standard rating
50 kVAR
Nearest standard size at or above 42.1 kVAR.
Typical catalog ratings
Apparent power before / after
125 / 105.26 kVA
Corrected load draws -19.74 kVA less.
kVA = kW ÷ PF
Line current before / after
150.35 / 126.61 A
At 480 V, three-phase.
I = kVA × 1000 ÷ (V × √3)
Engineering disclaimer: This design aid is not a substitute for engineering judgment. Confirm final design with a licensed professional engineer and the authority having jurisdiction.
How this was calculated
- Reactive-power demand: tan(cos⁻¹ 0.80) = 0.750; tan(cos⁻¹ 0.95) = 0.329.
- kVAR = 100 kW × (0.750 − 0.329) = 42.1 kVAR.
- Round up to the nearest typical catalog rating (50 kVAR) and verify the vendor's offered sizes.
- Apparent power falls from 125 to 105.26 kVA, reducing line current from 150.35 to 126.61 A at 480 V.
Engineering disclaimer: Capacitor placement, switching, and harmonics require an engineering study; follow NEC Article 460 (enclosures, discharge resistors, disconnecting means) and verify capacitor ratings with the manufacturer. Confirm final design with a licensed professional engineer.