# An Electric Motor Efficiency Calculation

What is the current in an electric motor operating with 85% efficiency and driving a 1.7-hp mechanical load with a supply voltage of 106 volts?

The current in the electric motor is 13.87 A.

## Calculating Electric Motor Current

**Power = Voltage x Current**. First, let's convert the mechanical load from horsepower to watts. Given 1 horsepower (hp) is equal to 736 watts (W), the mechanical load is: 1.7 hp x 736 W/hp = 1251.2 W. Next, using the efficiency of the electric motor (85%), we can calculate the input power: Input Power = Output Power / Efficiency Output Power = 1251.2 W Efficiency = 85% Input Power = 1251.2 W / 0.85 = 1471.06 W. Now, applying the formula Power = Voltage x Current, where the supply voltage is 106 volts: 1471.06 W = 106 V x Current Rearranging the equation to find the current: Current = Power / Voltage Current = 1471.06 W / 106 V Current = 13.87 A (approximately). Therefore, the current in the electric motor is approximately 13.87 A.