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.

single-phase full load current chart is as follow :

Load in KW Load in hp110V AC
(In amp)
220V AC
(In amp)
240V AC
(In amp)
0.07 kW1/122.4 A1.21.1
0.1 kW1/83.31.61.5
0.12 kW1/63.81.91.7
0.18 kW1/44.52.32.1
0.25 kW1/35.82.92.6
0.37 kW1/27.93.93.6
0.56 kW3/4115.55
0.75 kW1157.36.7
1.1 kW1.521109
1.5 kW2261312
2.2 kW3371917
3 kW4492422
3.7 kW5542725
4 kW5.5603027
5.5 kW7.5854138
7.5 kW101105550

3 phase motor full load current chart

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

kWHP220V AC
(In amp)
240V AC
(In amp)
380V AC
(In amp)
415V AC
(In amp)
550V AC
(In amp)
660V AC
(In amp)
690V AC
(In amp)
0.11/80.320.300.190.170.130.110.10
0.18¼0.580.530.340.310.230.190.19
0.251/30.810.740.470.430.320.270.26
0.37½1.191.100.690.630.480.400.38
0.56¾1.811.661.050.960.720.600.58
0.7512.422.221.401.280.970.810.77
1.11.403.553.262.061.881.421.181.13
1.525433222
2.237744322
3410965433
3.75121176544
45131277544
5.571816109766
7.510242214131088
9.31230281716121010
101332301917131110
111436332119141211
151948442826191615
182358533431231919
222871654138282423
303897895651393231
37471191106963484038
45571451338477584846
557017816310394715957
7595242222140128978177
901152912661681541169793
110140355326206188142118113
130165420385243223168140134
150191484444280257183161154

Direct Motor current full load chart ( FLA)

For direct motor full load current chart is as follow :

Power (hp) Power (kW)FOR 230 V DC
Current (A)
FOR 440 V DC
Current (A)
1/40.190.810.42
1/30.251.10.56
1/20.371.60.85
3/40.562.41.3
10.753.21.7
1.51.14.92.5
21.56.53.4
32.29.75.1
53.7168.5
7.55.62413
107.53217
15114925
20156534
30229751
503716285
7556243127
10075324170

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

To Find…Direct CurrentAlternating Current (Single Phase)Alternating Current(Two-Phase* Four-WireAlternating Current(Three Phase)
Amperes when Horsepower is known HP x 746
────────
E x EFF
HP x 746
────────
E x EFF x PF
HP x 746
────────
2 x E x EFF x PF
HP x 746
───────────
E x EFF x PF x 1.73
Amperes when Kilowatts are knownKW x 1000
────────
E
KW x 1000
────────
E x PF
KW x 1000
────────
2 x E x PF
KW x 1000
───────────
E x PF x 1.73
Amperes when “KVA” is known  ─KVA x 1000
────────
E
KVA x 1000
────────
2 x E
KVA x 1000
───────────
E x 1.73
Kilowatts E x I
────────
1000
E x I x PF
────────
1000
I x E x 2 x PF
────────
1000
E x I x 1.73 x PF
───────────
1000
Kilovolt-Amperes “KVA”  ─ I x E
────────
1000
I x E x 2
────────
1000
E x I x 1.73
────────
1000
Horsepower (Output)E x I x EFF
────────
746
E x I x EFF x PF
────────
746
I x E x 2 x EFF x PF
───────────
746
E x I x EFF x PF x 1.73
───────────
746

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

RELATED ARTICLE

https://www.electricalsells.com/kw-to-amps-calculator/
https://www.electricalsells.com/3-phase-motor-amps-calculation/

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