What current should a 7.5 kilowatt motor have?
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There is a water pump in the village, powered by a 7.5-kilowatt motor, which pumps water from the water tower to various households. If 220 volts is used, what would be the approximate current drawn by the motor in amperes? Generally speaking, how is it calculated? Those who know, please share. Thanks
To calculate the current of a motor, the following formula can be used: \ Where: - \( I \) is the current (amperes), - \( P \) is the power (watts), - \( V \) is the voltage (volts), - \( \cos\phi \) is the power factor, - \( \eta \) is the motor efficiency. For typical industrial motors, the power factor is approximately 0.8 to 0.9, and the efficiency is usually in the range of 0.8 to 0.9. Assuming a motor with a power of 7.5 kilowatts (i.e., 7500 watts), a voltage of 220 volts, a power factor of 0.85, and an efficiency of 0.85, plugging these values into the formula gives: Therefore, the current in this motor is approximately 49.5 amperes. This is just an estimate; the actual current may vary depending on the specific motor parameters and operating conditions. .
The current is 34.1 amps; however, the pump is usually driven by a 380V motor. For a 380V motor, the current is 19.8 amps.
This post was last edited by myface on 2024-9-9 09:09. How did you calculate this? The 220 one is considered too small, while the 380 one is considered too large. Got it. You didn’t calculate the power factor, and for 380V, you also didn’t account for 1.732.
This post was last edited by Hao Liang Zhi Le on 2024-10-22 at 16:05. Are there any 7.5 kW motors available in 220V? It seems there’s no three-phase 220V power supply anymore, right? For a 220V single-phase motor, is there a 7.5 kW 220V single-phase motor available? I’m ignorant and uninformed.
For motors with a power rating of 15KW or less, multiply the power by 2; for high-power motors, multiply the power by 1.8. This applies only to 380V motors. This is the simplest method of estimation