Exciting Electrical Motor Efficiency Calculation

How efficient is a 120-V motor with a mechanical power output of 2.20 hp?

a) What is the current in the motor?

b) How much energy is delivered to the motor by electrical transmission in 2.50 hours of operation?

c) If the electric company charges $0.110/kWh, what is the cost to run the motor for 2.50 hours?

Answers:

a) The current in the motor is 15.033 A.

b) The energy delivered to the motor is 1.804 kW.

c) The cost of running the motor for 2.50 hours is $0.496 USD.

Let's dive into the exciting world of electrical motor efficiency calculation! In this scenario, we have a 120-V motor with a mechanical power output of 2.20 hp that is 91.0% efficient in converting electrical power into mechanical power.

a) To find the current in the motor, we first calculate the electric power transmitted into the motor using the formula:

Electrical power transmitted into the motor = (2.20 hp) x (0.746 kW/hp) / 0.91

This gives us an input power of 1.804 kW. By dividing this power by the voltage (120 V), we find the current in the motor to be 15.033 A.

b) The energy delivered to the motor through electrical transmission in 2.50 hours of operation is simply the input power multiplied by the time:

Energy delivered = 1.804 kW x 2.50 h = 4.51 kWh = 1.804 MJ

c) To calculate the cost of running the motor for 2.50 hours, we multiply the energy consumed (1.804 kWh) by the electricity cost per kWh ($0.110):

Cost = 1.804 kWh x $0.110/kWh = $0.496 USD

So there you have it - a thrilling exploration of electrical motor efficiency and cost calculation!