What is the maximum setting for the separate overload protection of a 3-phase, 15 hp, 460 volt motor with a nameplate rating of 19 amps?

The maximum setting for the separate overload protection of a 3-phase motor is typically based on the nameplate rating of the motor, specifically its full-load current. For a 15 hp, 460 volt motor with a nameplate rating of 19 amps, the National Electrical Code (NEC) provides guidelines to determine the appropriate overload protection settings.

Under NEC guidelines, for motors above a certain horsepower rating (in this case, 15 hp), the overload protection can be set higher than the actual full-load current in certain scenarios, specifically when considering the rate of 125% of the full-load current rating. In this context, we calculate the maximum permissible setting for overload protection which is derived from the full-load current.

Calculating 125% of the nameplate current:

• 125% of 19 amps is 23.75 amps.

This calculation falls within the permissible range for separate overload protection as provided by the NEC. Therefore, the correct answer reflects the maximum allowable setting for this motor's overload protection, which ensures optimal performance while also protecting against potential overload situations.