Electrical Motor Horsepower

Reference data and engineering information about electrical motor horsepower for electrical applications.

electricalmotorhorsepowerCalculator

Overview

Engineering reference data for Electrical Motor Horsepower in electrical engineering.

Key Formulas

Ohm's Law

$V = IR$

Voltage = Current × Resistance.

Power

$P = VI = I^2R = V^2/R$

Electrical power.

Energy

$E = Pt$

Energy = Power × Time.

Variables

Symbol	Description	Unit
$V$	Voltage	V
$I$	Current	A
$R$	Resistance	Ω
$P$	Power	W

Standard Motor Horsepower Ratings

Standard NEMA horsepower ratings for electrical motors from 1 to 4000 hp are shown below. These motors are rated for nominal voltage not exceeding 600 V AC and nominal frequency of 50 or 60 Hz.

39 rows

Standard NEMA Horsepower Ratings for Electric Motors (1–4000 hp)
Horsepower(hp)
1
1.5
2
3
5
7.5
10
15
20
25
30
40
50
60
75
100
125
150
200
250
300
350
400
450
500
600
700
800
900
1000
1250
1500
1750
2000
2250
2500
3000
3500
4000

Source: engineeringtoolbox.com

Example: DC Motor Shaft Power Calculation

A direct current motor operates at 36 V, draws 5 amps, and has an efficiency of 85%.

Shaft power in kW:

$P_{shaft} = \frac{\eta_m \cdot U \cdot I}{1000} = \frac{0.85 \times 36 \times 5}{1000} = 0.153 \text{ kW} = 153 \text{ W}$

Shaft power in hp:

$P_{shaft} = \frac{0.153}{0.746} = 0.21 \text{ hp}$

References

Original Source

Source: engineeringtoolbox.com