What is the locked-rotor current in amps for a 10 hp, single-phase motor operating at 120 volts with the nameplate showing code letter F?

To find the locked-rotor current for a 10 hp, single-phase motor operating at 120 volts with a code letter F, one must understand how to use the NEMA (National Electrical Manufacturers Association) motor designations.

The locked-rotor current is calculated using the formula:

Locked-rotor current (Amps) = (Horsepower × 746) / (Voltage × Efficiency × Power Factor)

However, for the purposes of this question, we can simplify by using standard values that correspond to the code letter F. Each code letter indicates a specific locked-rotor current factor (in Amps) relative to the horsepower of the motor.

For a code letter F, typically associated with a maximum locked-rotor current of 5.25 to 6.0 times the full-load current, the locked-rotor current can be estimated from standard values available for 10 hp motors.

When we look at it in terms of full-load current (FLC) for a 10 hp motor at 120 volts, the FLC is approximately 50-60 amps. With a code letter F indicating a specific multiplier, the values can lead to a locked-rotor current of approximately 466 amps