What is the amp-load of a three-phase, 0.5-hp, 230-volt motor with an efficiency rating of 92% and a power factor of 80%?

To calculate the amp-load of a three-phase motor, you need to determine the output power in watts and then apply the formula for current in a three-phase system. The first step is to convert horsepower to watts. One horsepower is equivalent to approximately 746 watts, so a 0.5-hp motor translates to 373 watts (0.5 hp × 746 W/hp).

Next, because the motor has an efficiency of 92%, you should adjust for efficiency to find the input power (the actual power consumed). The input power can be calculated as follows:

Input Power = Output Power / Efficiency

Input Power = 373 W / 0.92 ≈ 405.43 W

Then, to account for the power factor, the actual power consumed (apparent power) can be calculated using the power factor of 80% (0.80). The formula for apparent power in a three-phase system is as follows:

Apparent Power (VA) = Input Power / Power Factor

Apparent Power = 405.43 W / 0.80 ≈ 506.79 VA

Finally, to find the current (I), we use the formula specific for three-phase systems:

I = Appar