Service Factor

Reference data and engineering information about service factor for miscellaneous applications.

servicefactorCalculator

Overview

Engineering reference data for Service Factor in miscellaneous.

Key Formulas

Unit Conversion

$y = x \cdot k$

Multiply by conversion factor.

Linear Interpolation

$y = y_1 + \frac{(x - x_1)(y_2 - y_1)}{x_2 - x_1}$

Estimate between two known points.

Percentage

$p = \frac{\text{part}}{\text{whole}} \times 100\%$

Part as fraction of whole.

Variables

Symbol	Description	Unit
$x$	Input value	—
$y$	Output value	—
$k$	Conversion factor	—

Key Formulas

$P_D = SF \times P$

Where:

$P_D$ = design power (hp, W)
$SF$ = service factor
$P$ = motor power (hp, W)

5 rows

NEMA Service Factors for Drip Proof Motors at Various Synchronous Speeds
Motor Power (hp)	3600 rpm	1800 rpm	1200 rpm	900 rpm
1/6, 1/4, 1/3	1.35	1.35	1.35	1.35
1/2	1.25	1.25	1.25	1.25
3/4	1.25	1.25	1.15	1.15
1	1.25	1.15	1.15	1.15
1 1/2 & up	1.15	1.15	1.15	1.15

Source: engineeringtoolbox.com

Notes

Operating continuously at a service factor >1 reduces the expected life of insulation and bearings compared to operating at nameplate horsepower.
The NEMA standard service factor for totally enclosed motors is 1.0.

Interactive Charts

electric motor

References

Original Source

Source: engineeringtoolbox.com