Calculated Result
This block appears above the form after submission.
| Phase System | Three Phase | Length | 1.0000 km |
|---|---|---|---|
| Adjusted Resistivity | 0.017918 Ω·mm²/m | Series Resistance | 0.188606 Ω |
| Total Inductance | 0.000400 H | Inductive Reactance | 0.125664 Ω |
| Total Capacitance | 0.000000012 F | Capacitive Reactance | 265,258.238486 Ω |
| Impedance Magnitude | 0.226635 Ω | Impedance Angle | 33.6746° |
| Estimated Source Current | 1,057.207951 A | Charging Current | 0.000903 A |
| Voltage Drop | 47.105208 V | Voltage Drop Percent | 11.350652 % |
| Apparent Power | 86.256130 kVA | Real Power | 77.630517 kW |
| Reactive Power | 37.598175 kVAr | Conductor Loss | 8.147762 kW |
Calculator Inputs
Example Data Table
| Material | Length (m) | Area (mm²) | Frequency (Hz) | Impedance (Ω) | Voltage Drop (%) |
|---|---|---|---|---|---|
| Copper | 600 | 70 | 50 | 0.169461 | 6.3654 |
| Aluminum | 1200 | 120 | 60 | 0.182255 | 0.4592 |
| Copper | 250 | 35 | 50 | 0.133268 | 1.8542 |
Formula Used
Temperature adjusted resistivity: ρT = ρref × [1 + α × (T − Tref)]
Single conductor resistance: Rsingle = (ρT × Length) ÷ Area
Series resistance with parallel conductors: R = Rsingle ÷ n
Total inductance: L = (Inductance per km × Length in km) ÷ n
Inductive reactance: XL = 2πfL
Series impedance magnitude: |Z| = √(R² + XL²)
Impedance angle: θ = tan−1(XL ÷ R)
Total capacitance: C = Capacitance per km × Length in km × n
Capacitive reactance: XC = 1 ÷ (2πfC)
Voltage drop: Single phase ≈ I × |Z|, Three phase ≈ √3 × I × |Z|
This page uses a simplified lumped model. Capacitance is reported as a shunt effect through charging current. It is not merged into the series impedance magnitude.
How to Use This Calculator
- Select the conductor material or choose Custom.
- Enter resistivity and temperature coefficient values.
- Fill in reference and operating temperatures.
- Enter line length and conductor cross sectional area.
- Provide frequency, inductance, and capacitance per kilometer.
- Set the number of parallel conductors and phase system.
- Enter line voltage, load current, and power factor.
- Press Calculate Impedance to show the result above the form.
- Use Download CSV to save the computed output table.
- Use Download PDF to print or save the report as a PDF.
Power Line Impedance and Electrical Performance
Power line impedance affects current flow, voltage drop, heating, and operating stability. Engineers, students, and technicians use impedance values to understand how a conductor behaves in an alternating current system. This calculator helps estimate resistance, inductive reactance, charging current, and phase angle in one practical workflow.
Resistance rises with conductor temperature. Longer lines also add more resistance. Larger conductor area reduces resistance and improves efficiency. These relationships matter when you compare copper and aluminum lines, plan feeder lengths, or check whether a selected cable can carry the expected load without excessive loss.
Inductive reactance is another major part of line behavior. It depends on frequency and total inductance. In alternating current systems, reactance shifts the phase angle between voltage and current. That shift changes impedance magnitude and affects apparent power, real power, and voltage regulation across the line.
Capacitance is especially useful for longer runs and cable studies. A line can store electric charge and create charging current even when load conditions are modest. This page handles capacitance as a shunt effect. That keeps the displayed series impedance focused on conductor resistance and inductive reactance, while still reporting capacitive reactance and charging current separately.
The calculator is useful for quick design checks, classroom exercises, maintenance planning, and comparison studies. You can test different conductor sizes, parallel runs, operating temperatures, and supply voltages. The voltage drop output helps you judge whether a line is likely to meet a practical delivery target before moving into more detailed modeling software.
This tool uses a simplified lumped model, so it is best for preliminary analysis. It does not replace a full transmission line study, manufacturer data, or utility protection analysis. Still, it gives fast, transparent results that make power line impedance easier to understand and easier to communicate.
Frequently Asked Questions
1. What does this calculator measure?
It estimates series resistance, inductive reactance, impedance magnitude, impedance angle, charging current, and voltage drop for a simplified power line model.
2. Why does temperature change the result?
Conductor resistivity increases as temperature rises. Higher temperature creates higher resistance, which raises impedance, losses, and voltage drop.
3. Why are parallel conductors included?
Parallel conductors reduce effective series resistance and approximate a lower inductive effect per path. They can improve current sharing and lower impedance in practical designs.
4. Why is capacitance not added directly to impedance magnitude?
Line capacitance behaves mainly as a shunt effect, not a simple series term. This calculator reports it through capacitive reactance and charging current for clearer interpretation.
5. Can I use this for single phase systems?
Yes. Choose Single Phase in the form. The page then applies the single phase voltage and current relationship for the estimated drop and source current values.
6. Can this tool help with underground cable checks?
Yes, for quick estimates. Enter cable specific inductance, capacitance, conductor area, and material data. Final design work should still use manufacturer and utility grade models.
7. Which units should I enter?
Use meters for line length, square millimeters for area, hertz for frequency, millihenry per kilometer for inductance, and microfarad per kilometer for capacitance.
8. Is this accurate enough for protection studies?
It is suitable for screening and learning, not final protection coordination. Detailed studies need source impedance, sequence components, grounding, fault levels, and utility data.