In order to properly set up programmable motor protection, it is necessary to know the locked rotor current of a motor. Given the chart of code letters for locked-rotor kVA/HP and the necessary instructions shown in the illustration, calculate the estimated locked rotor current for the motor represented by the illustrated motor nameplate using a mid-range value for the code letter, assuming the motor is to run at 440 VAC. EL-0175

Illustration EL-0175: the U.S. Coast Guard has not released this illustration.

Question

In order to properly set up programmable motor protection, it is necessary to know the locked rotor current of a motor. Given the chart of code letters for locked-rotor kVA/HP and the necessary instructions shown in the illustration, calculate the estimated locked rotor current for the motor represented by the illustrated motor nameplate using a mid-range value for the code letter, assuming the motor is to run at 440 VAC. EL-0175

Illustration EL-0175: the U.S. Coast Guard has not released this illustration.

Accepted Answer

Option B: 43.7 amps. Locked-rotor kVA per horsepower is determined using the motor nameplate code letter mid-range value. Applying standard formulas for a 440V three-phase system yields the estimated locked-rotor current of 43.7 amps, essential for proper overcurrent protection sizing under 46 CFR Subchapter J standards.