# Motor full load current chart

## What is motor Full Load Current

Full Load Current is the maximum allowable current that is tolerated by the motor insulation. The input current to the machine exceeds the full load current means, the electrical machine may get damaged. Due to the excess current flow, the machine produces additional heat (Because of heat /loss =I2 R)., This may lead to damages to the insulation or winding of the electrical motor. Hence, Operating a machine below full load current increases the life span of the electrical motor. In this article, we will see motor full load current chart for 3 phase motor, single-phase motor, and direct motor.

As a “rules of thumb” amps horsepower rating can be estimated to

• 110 volts motor – single-phase : 14 amps/hp
• 220 volts motor – single-phase : 8 amps/hp
• 220 volts motor – 3-phase : 2.2 amps/hp
• 415 volts motor – 3-phase : 1.3 amps/hp

Single-phase motor full load current chart

The tables are based on motors of approximately 1500rpm of average efficiency and power factor. Motors of higher speed usually take a lower current than that shown in the table; while motors of lower speed usually take higher current. Wide variations from these figures can arise, especially on single-phase motors, and engineers should, whenever possible, determine the actual full load current from the motor rating plate.

3 phase motor full load current chart

The following chart is the full load current chart for 3 phase motor :

Direct Motor current full load chart ( FLA)

## Formula for Full load current calculation of AC motors

Formula used for full load current calculation of AC motors are as follow-

Single Phase AC Motor Full load current (Amperes) = (P [kW] × 1000) / (V × cos ϕ)

Single Phase AC Motor FLC (Amperes) = (P [HP] × 746) / (V × cos ϕ × η)

Three Phase AC Motor FLC (Amperes) = (P [kW] × 1000) / (V × 1.732 × cos ϕ)

Three Phase AC Motor FLC (Amperes) = (P [HP] × 746) / (V × 1.732 × cos ϕ × η)

Where:

P [HP] , P [kW] = Motor power rating (HP or kW),

V = Motor rated voltage (Volts),

η = Motor efficiency for example – 0.90,

cos ϕ = Motor power factor,

1000 = Conversion factor to convert kW to W,

746 = Conversion factor to convert HP to W.

## 3 phase motor amps calculation & formula

Where E = Voltage, I = Amps, PF = Power Factor, EFF = Efficiency, HP = Horsepower

RELATED ARTICLE