Question 255Electricity & Electronics - Assistant Engineer
70% to passIn 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. Illustration EL-0175
A34.7 amps
B43.7 amps
C60 amps
D75.6 amps
AI Explanation
The correct answer is B) 43.7 amps. To calculate the estimated locked-rotor current for the motor represented by the illustrated motor nameplate, we need to use the chart of code letters for locked-rotor kVA/HP and the necessary instructions shown in the illustration. The motor nameplate indicates a code letter of 'J', which corresponds to a locked-rotor kVA/HP range of 7.1-8.0 according to the chart. Using the mid-range value of 7.55 kVA/HP and the 440 VAC voltage, the estimated locked-rotor current is calculated to be 43.7 amps. The other options are incorrect because they do not match the calculated value based on the provided information.
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