Star Delta Motor Cable Size Calculator

Calculate cable sizes for star and delta motor connections

Star Delta Cable Size Calculator

Compliant with IEC 60034 Standards

Results:

Motor Full Load Current (A): 0.00

Delta Current (A): 0.00

Star Current (A): 0.00

Required Cable Size (mm²): 0.00

Select next standard size of cable

Motor Torque Calculator
Motor Current Calculator

How to Use the Calculator

Input Motor Details

  1. Select input type (kW or HP) and enter the motor power.
  2. Enter the motor's operating Voltage (V).
  3. Input the Power Factor (PF) of the motor (typically 0.8 to 0.9).

Input Cable Details

  1. Select the cable material (Copper or Aluminium).
  2. Enter the total Cable Distance (m) from the supply to the motor.
  3. Click 'Calculate' to get results.

Understand Results

  1. View Motor Full Load Current (FLC).
  2. See calculated Delta Current (58% of FLC).
  3. See calculated Star Current (33% of FLC).
  4. Get the Recommended Cable Size (mm²) based on Delta Current.

Star Delta Motor Fundamentals

Star Delta Starting

Star-delta (Y-Δ) starting is a common method for reducing the starting current of three-phase induction motors. It involves starting the motor in a star (Y) configuration and then switching to a delta (Δ) configuration once the motor has accelerated.

Current Reduction

  • Star Current: Approximately 33% (1/√3) of the full load current. This reduces the initial inrush current.
  • Delta Current: Approximately 58% (1/√3) of the full load current. This is the current the motor draws during normal running in delta connection.

Key Formulas:

Motor FLC (3-Phase): I_FLC = (P_kW * 1000) / (sqrt(3) * V * PF)

Delta Current: I_Delta = 0.58 * I_FLC

Star Current: I_Y = 0.33 * I_FLC

Cable Sizing Formulas

Cable sizing is based on the Delta Current (I_Delta).

Copper Cable:
Distance > 50m: Area_Cu = I_Delta / 2.5
Distance ≤ 50m: Area_Cu = I_Delta / 3

Aluminium Cable:
Distance > 50m: Area_Al = I_Delta / 1.5
Distance ≤ 50m: Area_Al = I_Delta / 2

Example Calculation

Motor: 15 kW, 400V, 0.8 PF

Cable: Copper, 60m distance

1. Motor FLC = (15 * 1000) / (√3 * 400 * 0.8) ≈ 27.06 A

2. Delta Current = 0.58 * 27.06 A ≈ 15.69 A

3. Star Current = 0.33 * 27.06 A ≈ 8.93 A

4. Cable Size (Copper, >50m) = 15.69 A / 2.5 A/mm² ≈ 6.28 mm²

Recommended Cable Size: 6.28 mm²

Related Motor Calculators

Motor RPM Calculator

Calculate the rotational speed of an AC motor.

Try Calculator

Motor Contactor Size Calculator

Determine the appropriate contactor size for your motor.

Try Calculator

Motor Capacitor Calculator

Calculate the required capacitor size for single-phase motors.

Try Calculator