Why are the SF amps and FL amps different even though SF = 1.0?
In NEMA MG 1 there are tables that list, by Hp rating, required service factors for motors of design A, B, and C. Motors of other designs have SF 1.0 specified. Per the nameplate, the motor in question is Design L. It appears that SF current is marked when the SF does not conform to NEMA standards. Operating at service factor &gt; 1.0 does not have a specific time limit, but it results in reduced life expectancy for the insulation and bearings. The amount of reduced life expectancy is not specified by NEMA. SF is a multiplier applied to the Hp rating. When operating above 1.0 SF, the current and torque increase and the speed decreases by unspecified amounts. In this case, the manufacturer has chosen to mark SF as a multiplier for current with unspecified Hp and speed at current greater than rated current.