Calculator Inputs
Example Data Table
| System | Load (kW) | Voltage (V) | PF | Length (km) | R/km (ohm) | X/km (ohm) | Temp Factor |
|---|---|---|---|---|---|---|---|
| Three Phase | 250 | 11000 | 0.92 | 12 | 0.18 | 0.12 | 1.00 |
| Single Phase | 45 | 415 | 0.88 | 1.5 | 0.26 | 0.08 | 1.06 |
| Three Phase | 600 | 33000 | 0.95 | 25 | 0.11 | 0.15 | 1.03 |
Formula Used
Single phase current: I = P / (V × pf)
Three phase current: I = P / (√3 × V × pf)
Adjusted resistance: Radj = Rper km × temperature factor
Single phase loss: Ploss = I² × Rloop
Three phase loss: Ploss = 3 × I² × Rphase total
Voltage drop: For single phase, Vdrop = I × (R × cosφ + X × sinφ). For three phase, Vdrop = √3 × I × (R × cosφ + X × sinφ).
Efficiency: Efficiency = Output Power / (Output Power + Line Loss) × 100
Annual loss cost: Annual loss kWh = loss kW × operating hours per day × 365. Cost = annual loss kWh × energy cost.
How to Use This Calculator
Start by choosing single phase or three phase operation. Enter the delivered load power, system voltage, power factor, and one way line length.
Next, supply conductor resistance and reactance values per kilometer. Add a resistance temperature factor when hot operating conditions raise conductor resistance.
Optionally enter daily operating hours and energy cost. These values help estimate yearly wasted energy and its financial effect.
Press the calculation button. The results section appears above the form and summarizes current, voltage drop, total loss, efficiency, and estimated yearly loss cost.
Use the CSV button for spreadsheet work. Use the PDF button to save or print the full page as a report.
FAQs
1. What does this calculator estimate?
It estimates current, voltage drop, resistive power loss, receiving end voltage, efficiency, thermal dissipation, annual energy waste, and yearly loss cost.
2. Why is power factor included?
Power factor affects current magnitude for a given real power. Lower power factor increases current, which raises I²R losses and usually worsens voltage drop.
3. Why do single phase and three phase formulas differ?
Single phase circuits use a full return path, while three phase systems distribute current differently across phases. That changes total resistance treatment and voltage drop relationships.
4. What is the temperature factor for?
Conductors get hotter under load and at higher ambient temperatures. Higher temperature raises resistance, so the factor lets you model more realistic loss results.
5. Is reactance used in loss calculations?
No. The loss calculation here is based on resistive heating. Reactance is included for approximate voltage drop because it changes the voltage relationship with current and phase angle.
6. Are these results suitable for final protection studies?
No. This page is for engineering estimation and comparison. Detailed design should also consider conductor geometry, frequency effects, unbalance, harmonics, corona, and standards.
7. What voltage should I enter?
Enter the sending end operating voltage for the line. The calculator then estimates the drop and reports an approximate receiving end voltage.
8. Can I compare conductor options with this page?
Yes. Change resistance, reactance, and temperature factor values for each option. Lower resistance generally reduces heating losses and improves efficiency.