Question 1

What is the difference between kW, kVA, and kVAR?

Accepted Answer

kW (kilowatts) is real power that does actual work like running motors. kVA (kilovolt-amps) is apparent power - the total power your system draws. kVAR (kilovolt-amps reactive) is reactive power needed to maintain magnetic fields but does no useful work. PF = kW/kVA.

Question 2

Why is a low power factor bad?

Accepted Answer

Low power factor means you draw more current than necessary for your actual work, causing: higher electricity bills (demand charges), larger wire/transformer requirements, increased I²R losses, and possible utility penalties. Most utilities penalize PF below 0.85-0.90.

Question 3

How do I improve power factor?

Accepted Answer

Add capacitor banks to supply reactive power locally instead of drawing it from the utility. Size the capacitor bank using kVAR = kW × (tan θ₁ - tan θ₂). Common correction targets are 0.95 to avoid penalties and reduce demand charges.

Question 4

What causes low power factor?

Accepted Answer

Inductive loads cause lagging power factor: lightly loaded motors, welding machines, induction furnaces, fluorescent lighting with magnetic ballasts, and VFDs with poor input filtering. Leading PF (rare) comes from over-corrected capacitors.

Question 5

How does power factor affect transformer sizing?

Accepted Answer

Transformers are rated in kVA (apparent power), not kW (real power). A facility drawing 100 kW at 0.85 PF requires 117.6 kVA from the transformer — 17.6% more capacity than the actual useful work. Improving PF to 0.95 reduces the required kVA to 105.3 — freeing 12.3 kVA of transformer capacity. This means you can either use a smaller transformer (saving $2,000–$10,000 depending on size) or serve additional load from the existing transformer without upgrading. For facilities approaching transformer capacity limits, PF correction is often cheaper than a transformer upgrade.

Power Factor	Rating	Action
≥ 0.95	Excellent	No correction needed
0.90 - 0.94	Good	Consider correction for savings
0.80 - 0.89	Fair	Correction recommended
< 0.80	Poor	Correction required, likely penalties

Power Factor Triangle Calculator

Calculator Inputs

Calculation Results

Example Calculations

100 kW at 0.85 PF

How to Use

Quick Answer

Power Triangle Relationships

From kW and Power Factor:

From kW and kVAR:

Power Factor Correction Formula:

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