1. What is 3-Phase Voltage Drop Calculation?

Definition: This calculator estimates the voltage drop in a three-phase electrical circuit according to UK standards.

Purpose: It helps electricians and engineers ensure proper voltage levels in three-phase power distribution systems.

2. How Does the Calculator Work?

The calculator uses the standard UK three-phase voltage drop formula:

Where:

• \( VD \) — Voltage drop (volts)
• \( I \) — Current (amps)
• \( L \) — Cable length (meters)
• \( R \) — Resistance per meter (ohms/m)
• \( X \) — Reactance per meter (ohms/m)
• \( φ \) — Power factor angle (degrees)

Explanation: The formula accounts for both resistive and reactive components of impedance in a three-phase system.

3. Importance of Voltage Drop Calculation

Details: Proper voltage drop calculation ensures equipment operates within specified voltage tolerances and complies with IET Wiring Regulations (BS 7671).

4. Using the Calculator

Tips: Enter the current in amps, cable length in meters, resistance and reactance in ohms per meter, and power factor angle in degrees.

5. Frequently Asked Questions (FAQ)

Q1: What's the maximum allowable voltage drop in the UK?
A: For lighting circuits, 3% of supply voltage; for other circuits, 5% (IET Regulations).

Q2: Where do I find R and X values?
A: These are typically provided in cable manufacturer datasheets or the IET On-Site Guide.

Q3: What's a typical power factor angle?
A: For general power circuits, 30° (pf ≈ 0.86) is common, but this varies by load type.

Q4: Does this work for single-phase systems?
A: No, for single-phase use VD = 2 × I × L × (R cosφ + X sinφ).

Q5: How does cable temperature affect results?
A: Higher temperatures increase resistance. Use values corrected for operating temperature.