Permissible horsepower loading
Motor Service Factor (SF) is the percentage of overloading the motor can handle for short periods when operating normally within the correct voltage tolerances. This is practical as it gives you some ‘fudge‘ in estimating horsepower needs and actual running horsepower requirements.
It also allows for cooler winding temperatures at rated load, protects against intermittent heat rises, and helps to offset low or unbalanced line voltages.
BALDOR Open Drip Proof C-Face Foot Mounted motor - 1/3Hp-100Hp NEMA 56C-404TC
BALDOR Open Drip Proof C-Face Foot Mounted motor - 1/3Hp-100Hp NEMA 56C-404TC
For example, the standard SF for open drip-proof (ODP) motors is 1.15. This means that a 10-hp motor with a 1.15 SF could provide 11.5 hp when required for short-term use. Some fractional horsepower motors have higher service factors, such as 1.25, 1.35, and even 1.50.

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