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Calculation of voltage drop

V
Description

Calculate voltage drop in DC and AC circuits using key electrical parameters.

"Voltage drop is the decrease of electrical potential along the path of a current flowing in an electrical circuit. According to Annex G – IEC 60364–5–52."

Key Parameters

Current Type

Direct Current (DC): Current flows constantly from positive to negative pole. Used in batteries, solar panels, and electronics.

Alternating Current (AC): Current reverses direction and amplitude over time at a constant frequency (e.g., 50 Hz or 60 Hz). Used in power grids and homes.

System Types:

  • Single-phase: One phase conductor and one neutral.
  • Two-phase: Two phase conductors (rare).
  • Three-phase: Three phase conductors; four-wire includes neutral.
  • Unipolar: One conductor.
  • Bipolar: Two conductors.
  • Tripolar: Three conductors.
  • Quadrupolar: Four conductors.
  • Pentapolar: Five conductors.
  • Multipolar: Two or more conductors.

Operating Temperature

Permissible operating temperature depending on the conductor insulation material.

IEC/CEI:

  • 70°C (158°F): PVC insulation, PVC-coated mineral insulation, or accessible bare mineral insulation.
  • 90°C (194°F): XLPE, EPR, or HEPR insulation.
  • 105°C (221°F): Bare and non-accessible mineral insulation.

NEC:

  • 60°C (140°F): Types TW, UF
  • 75°C (167°F): RHW, THHW, THW, THWN, XHHW, USE, ZW
  • 90°C (194°F): TBS, SA, SIS, FEP, FEPB, MI, RHH, RHW-2, THHN, THHW, THW-2, THWN-2, USE-2, XHH, XHHW, XHHW-2, ZW-2

Phase Conductors in Parallel

Conductors of the same cross-sectional area, length, and material can be connected in parallel. The maximum permissible current is the sum of the individual-core maximum currents.

Line Length

Distance between supply point and load (one way), measured in meters or feet. Longer lines result in higher voltage drop.

Conductor

Material used for the conductor. Common materials include copper (lower resistance) and aluminum (lighter, cheaper).

Cable Type

Defines the number of conductors in the cable:

  • Unipolar: One conductor
  • Bipolar: Two conductors
  • Tripolar: Three conductors
  • Quadrupolar: Four conductors
  • Pentapolar: Five conductors
  • Multipolar: Two or more conductors

Voltage

Difference in electric potential between two points.

Enter Phase-Neutral voltage for single-phase systems (e.g., 120V).

Enter Phase-Phase voltage for two-phase or three-phase systems (e.g., 208V, 480V).

Load

Power to be considered for determining circuit characteristics, measured in watts (W) or kilowatts (kW). Includes all connected devices.

Power Factor (PF)

Ratio of active power to apparent power: cosφ, where φ is the phase angle between voltage and current.

Value ranges from 0 to 1. Ideal = 1 (purely resistive load).

Wire Size

Cross-sectional area of the conductor, measured in mm² or AWG.

Larger size → lower resistance → less voltage drop.

Key Formulas (Pure HTML)

VD = I × R × L
VD (%) = (VD / V) × 100
R = ρ × L / A

Application Scenarios

  • Designing electrical installations in buildings
  • Sizing wires for long-distance power transmission
  • Troubleshooting dim lights or motor issues
  • Compliance with IEC 60364 and NEC standards
  • Industrial plant planning
  • Renewable energy systems (solar, wind)

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