Calculator Inputs
Use the form below. The calculator grid shifts to three, two, and one columns by screen size.
Example Data Table
This example shows one sample scenario using the same calculation logic.
| Nominal V | Fundamental V | Fundamental A | VTHD % | ITHD % | True PF | Real kW | Score | Severity |
|---|---|---|---|---|---|---|---|---|
| 230.00 | 228.00 | 42.00 | 3.42 | 15.07 | 0.9493 | 9.198 | 97.92 | Excellent |
Formula Used
This page combines distortion, voltage variance, and power relationships into one project-facing quality view.
Voltage THD = sqrt(V3² + V5² + V7² + V9²) / V1 × 100 Current THD = sqrt(I3² + I5² + I7² + I9²) / I1 × 100 Total RMS Voltage = sqrt(V1² + harmonic voltage squares) Total RMS Current = sqrt(I1² + harmonic current squares) Distortion Factor = 1 / sqrt(1 + (ITHD / 100)²) True Power Factor = Displacement Power Factor × Distortion Factor Apparent Power = Total RMS Voltage × Total RMS Current / 1000 Real Power = Apparent Power × True Power Factor Reactive Power = sqrt(Apparent² - Real²) Voltage Deviation = |Total RMS Voltage - Nominal Voltage| / Nominal Voltage × 100Power Quality Score: The score starts at 100 and subtracts weighted penalties for voltage deviation, excessive voltage THD, excessive current THD, and low true power factor.
Estimated Cost Proxy: This is a planning proxy, not a utility tariff. It multiplies baseline energy cost by a distortion penalty term so teams can compare scenarios and prioritize work.
How to Use This Calculator
- Enter the nominal system voltage.
- Enter the measured fundamental voltage and current.
- Add the displacement power factor.
- Provide project hours and energy rate for planning.
- Enter voltage harmonic percentages for 3rd, 5th, 7th, and 9th orders.
- Enter current harmonic percentages for the same orders.
- Press the calculate button.
- Review the result block above the form.
- Study the chart, score, and recommended actions.
- Download CSV or PDF for reporting and handoff.
Frequently Asked Questions
1. What does this calculator estimate?
It combines harmonic distortion, RMS values, true power factor, power quantities, a planning score, and a disturbance cost proxy. This helps project teams compare sites, rank risks, and summarize electrical quality in one consistent view.
2. Why are voltage and current harmonics both included?
Voltage harmonics reveal source distortion. Current harmonics show how loads pollute the system. Reviewing both helps teams decide whether the problem mainly sits in the supply path, the connected equipment, or both together.
3. Is the cost proxy a real utility charge?
No. It is a planning metric for comparing scenarios. It does not replace site tariffs, utility penalties, or a detailed billing model. Use it to rank improvement options and justify follow-up engineering work.
4. What score range is considered good?
Higher is better. Scores above 90 indicate strong conditions. Scores from 75 to 89 are usually workable. Lower scores suggest rising distortion, deviation, or power factor concerns that deserve attention.
5. Can this support project status reporting?
Yes. The score, severity label, chart, and export options make it useful for dashboards, meeting packs, closeout files, and maintenance planning. It turns technical readings into simpler management signals.
6. Why does true power factor differ from displacement power factor?
Displacement power factor measures phase shift between voltage and current fundamentals. True power factor also reflects distortion. When current harmonics rise, the distortion factor drops and true power factor becomes lower than displacement power factor.
7. What harmonic limits should teams watch first?
Many teams first monitor voltage THD near 5 percent, current THD near 20 percent, true power factor below 0.95, and voltage deviation above 5 percent. Final limits should still follow your local standards and equipment needs.
8. Can I expand this calculator later?
Yes. You can add more harmonic orders, three-phase calculations, demand charges, equipment sensitivity classes, or trend history. The page structure already supports reporting, graphing, and export workflows.